JP2005100973A - Light emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element excellent in luminous efficiency, bright with low power consumption, and high in stability. <P>SOLUTION: An insulating or half-insulating barrier layer having a thickness to allow a tunnel current to pass through is provided between a hole injection electrode and a hole transporting organic compound layer (hole injection layer or hole transportation layer). That is, the thin insulating or half-insulating barrier layer containing silica or silicon oxide, silica or silicon oxide and a translucent oxide conductive material, or silica or silicon oxide, a translucent oxide conductive material, and carbon is provided between a translucent oxide conductive film comprising the translucent oxide conductive material such as ITO, and the hole injection layer comprising an organic compound. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting element using an electroluminescent material, and more particularly to an element structure of a light emitting element in which an organic compound layer is laminated between a pair of electrodes.

  A light-emitting element that exhibits electroluminescence (hereinafter also referred to as “EL”) by interposing a layer mainly containing an organic compound between a pair of electrodes has attracted attention. In this light-emitting element, the holes injected from one electrode and the electrons injected from the other electrode recombine to excite the emission center and emit light when it returns to the ground state. Is used. That is, this light-emitting element is formed such that organic compounds having different carrier transport properties are stacked between a pair of electrodes, holes are injected from one electrode, and electrons are injected from the other electrode. The injectability of holes and electrons into an organic compound is regarded as one index based on the work function of the material forming the electrode, and the work function of the electrode on the hole injection side is preferably high. A material having a low work function is desired for the electrode on the injection side.

  Conventionally, an indium tin oxide (ITO) having a work function of about 5 eV has been used for an electrode called an anode on the side of injecting holes, which has been brought into contact with an organic compound having a high hole transporting property. . In addition, an electrode called a cathode, which is used for injecting electrons, is made of a material having a low work function and containing an alkali metal or alkaline earth metal such as Li or Mg, and has a high electron transporting property. Forming contact.

Examples of the organic compound include a hole injection layer such as copper phthalocyanine (CuPc), and 4,4′-bis- [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD) which is an aromatic amine material. In addition to a hole transport layer such as tris-8-quinolinolato aluminum complex (Alq ₃ ), a light emitting material such as Alq ₃ and rubrene, and a guest material such as quinacridone as a host material A light emitting layer to which a material is added is known.

  In order to improve the characteristics of light-emitting elements, electrons and holes are efficiently injected from the electrode, the injected charges are efficiently transported to the light-emitting layer, the recombination efficiency of electrons and holes is improved, and recombination is performed. There is a need to increase the luminous efficiency later.

  However, in a light emitting device having a structure in which a conventional organic compound is stacked on an electrode formed of an inorganic material, sufficient luminance cannot be obtained. In addition, the power consumption is high, the half life of luminance is short, and there are problems to be improved regarding stability.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a light-emitting element that has good light-emitting characteristics, is bright with low power consumption, and has high stability.

  The present invention comprises an electrode (anode) on the hole injection side (hereinafter referred to as “hole injection electrode”) and a layer containing a hole transporting organic compound (hole injection layer or hole transport layer). It is a light emitting element provided with an insulating or semi-insulating barrier layer through which a tunnel current flows. That is, a thin insulating or semi-insulating material containing silicon or silicon oxide and a light-transmitting oxide conductive material between a light-transmitting oxide conductive film typified by ITO and a hole injection layer containing an organic compound It is a light emitting element in which the barrier layer is interposed. Alternatively, the light-emitting element includes a thin insulating or semi-insulating barrier layer including silicon or silicon oxide, a light-transmitting oxide conductive material, and carbon.

  One of the light-emitting elements of the present invention is between a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound. In addition, an insulating or semi-insulating barrier layer through which a tunnel current flows is provided.

  One of the light-emitting elements of the present invention is between a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound. Further, an insulating or semi-insulating barrier layer for improving the hole injection efficiency is provided.

  In a light-emitting element of the present invention, a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound are in close contact with each other. In order to prevent this, an insulating or semi-insulating barrier layer through which a tunnel current flows is provided.

  In a light-emitting element of the present invention, a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound are in close contact with each other. Therefore, an insulating or semi-insulating barrier layer that improves the hole injection efficiency is provided.

  One of the light-emitting elements of the present invention is between a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound. In addition, a barrier layer is provided. The barrier layer is formed on the surface of the hole injection electrode and contains silicon or silicon oxide.

  In a light-emitting element of the present invention, a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound are in close contact with each other. In order to prevent this, a barrier layer containing silicon or silicon oxide is provided on the surface of the hole injection electrode.

  According to one aspect of the present invention, an insulating or semi-insulating barrier layer through which a tunnel current flows is formed on the surface of a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide. Forming a hole injection layer or a hole transport layer formed of an organic compound on the layer;

  According to one aspect of the present invention, an insulating or semi-insulating barrier layer that improves hole injection efficiency is formed on the surface of a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide. And a step of forming a hole injection layer or a hole transport layer formed of an organic compound on the barrier layer.

  One aspect of the present invention is a barrier layer formed by selectively removing indium tin oxide and leaving silicon or silicon oxide on the surface of a hole injection electrode formed of silicon or indium tin oxide containing silicon oxide. And forming a hole injection layer or a hole transport layer formed of an organic compound on the barrier layer.

  According to one aspect of the present invention, a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide is formed on an insulating surface, and a photosensitive organic resin material is applied thereon, followed by an exposure process. And developing so as to remove the non-photosensitive portion, forming an organic resin layer having an opening through which the hole injection electrode is exposed, and forming a hole injection layer formed of an organic compound on the conductive layer after the heat treatment. Forming.

  For the light-transmitting oxide conductive layer, other light-transmitting oxide conductive materials such as indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), and zinc oxide added with gallium (GZO) are used. It is possible. Preferably, the hole injection electrode is formed by sputtering a target material containing the light-transmitting oxide conductive material and silicon oxide.

  In the light emitting device configured as described above, since the hole injection electrode and the hole injection layer are not in direct contact with each other, the effect of the original work function of the hole injection electrode is exhibited, and the hole in the hole injection layer Injection efficiency is improved, and light emission characteristics can be improved.

  Embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Note that in the modes described below, the same reference numeral is used in common in different drawings.

  The light-emitting element includes a hole-injecting electrode formed of a light-transmitting oxide conductive layer and an electron-injecting electrode (cathode) containing an alkali metal or an alkaline earth metal (hereinafter referred to as “electron-injecting electrode”). It has an element structure in which layers containing an organic compound that expresses EL are stacked. The layer containing an organic compound is preferably stacked including a hole transport layer, a light emitting layer, an electron transport layer, and the like. Further, a hole injection layer may be provided between the hole injection electrode and the hole transport layer. An electron injection layer may be provided between the electron injection electrode and the electron transport layer. The distinction between a hole injection layer and a hole transport layer, and an electron injection layer and an electron transport layer is not necessarily strict, and these are hole transportability (hole mobility) and electron transportability (electron mobility). Is the same in the sense that is a particularly important property. Alternatively, a hole blocking layer may be provided between the electron transport layer and the light emitting layer. The light emitting layer may have a configuration in which a guest material such as a pigment or a metal complex is added to the host material to change the emission color. That is, the light emitting layer may be formed by including a fluorescent material or a phosphorescent material.

  The layer containing an organic compound or the organic compound layer includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like from the viewpoint of carrier transport characteristics. The distinction between a hole injection layer and a hole transport layer is not necessarily strict. These are the same in the sense that hole transportability (hole mobility) is a particularly important characteristic. For convenience, the hole injection layer is a layer in contact with the anode, and the layer in contact with the hole injection layer is referred to as a hole transport layer for distinction. The same applies to the electron transport layer and the electron injection layer. The layer in contact with the cathode is called an electron injection layer, and the layer in contact with the electron injection layer is called an electron transport layer. The light emitting layer may also serve as an electron transport layer, and is also referred to as a light emitting electron transport layer. In addition, a light-emitting element is replaced not only with an organic compound but also with a material in which an organic material and an inorganic material are combined, or a material in which a metal complex is added to an organic compound. And can be applied.

  The hole injecting electrode is made of silicon oxide on a light-transmitting oxide conductive layer selected from indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), zinc oxide added with gallium (GZO), and the like. The one containing 1 to 10 atomic% is used. Preferably, the concentration of silicon oxide is increased on the surface of the hole injection electrode in contact with the organic compound layer. By increasing the concentration of silicon oxide, an insulating or semi-insulating barrier layer is formed on the surface of the hole injection electrode. The barrier layer has a thickness such that carriers can move between the two layers of the hole injection electrode and the organic compound layer.

  Alternatively, a barrier layer in which silicon oxide or a combination of a silicon oxide and a light-transmitting oxide conductive layer is provided with a thickness to which a current flows due to a tunnel current is provided. The barrier layer has a composition different from that of the underlying hole injection electrode. Therefore, even when provided between the hole injection electrode and the organic compound layer, non-diode characteristics (non-rectifying property) are exhibited. The barrier layer enables carrier movement between the hole injection electrode and the organic compound layer, and separates the hole injection electrode and the organic compound layer. By providing the barrier layer, the hole injection electrode and the organic compound layer are not in direct contact with each other. With this structure, the original work function effect of the hole injection electrode can be exhibited. That is, the efficiency of hole injection into the organic compound layer is improved, and the light emission characteristics can be improved.

  The hole injection electrode including the light-transmitting oxide conductive layer can be formed by a sputtering method using a target including the light-transmitting oxide conductive material and silicon oxide. In the target, the content of silicon oxide in the light-transmitting oxide conductive layer may be 1 to 20% by weight, preferably 2 to 10% by weight. When the ratio of silicon oxide is increased, the resistivity of the hole injection electrode is increased. Therefore, it may be appropriately formed within this range. Thereby, a hole injection electrode containing 1 to 10 atomic%, preferably 2 to 5 atomic% of silicon in the light-transmitting oxide conductive layer can be obtained. Needless to say, if a similar composition can be obtained, the light-transmitting oxide conductive material and silicon oxide may be co-evaporated by a vacuum evaporation method.

  The barrier layer can be formed by selectively removing the light-transmitting oxide conductive material from the surface of the light-transmitting oxide conductive layer containing silicon oxide. That is, it can be formed by increasing the component ratio of silicon oxide added to the translucent oxide conductive layer. One of the formation methods is a method of treating the surface with a solution capable of selectively removing the light-transmitting oxide conductive material. In addition, the surface of the light-transmitting oxide conductive layer can be obtained by plasma treatment using one or more kinds of gases selected from hydrogen, oxygen, and fluorine, and plasma treatment using an inert gas such as nitrogen and argon. A barrier layer can be formed. The insulating or semi-insulating barrier layer may be formed by forming a silicon or silicon oxide film on the light-transmitting oxide conductive layer by a vacuum deposition method, a sputtering method, a vapor phase growth method, or the like. The barrier layer may be a film formed by spin-coating a solvent containing silicon or silicon oxide and then baking. In any case, the barrier layer only needs to be a composite of silicon or silicon oxide and a light-transmitting oxide conductive material, or silicon or silicon oxide, a light-transmitting oxide conductive material, and carbon. .

  Examples of the hole injection layer include a hole injection layer such as copper phthalocyanine (CuPc), and 4,4′-bis- [N- (naphthyl) -N-phenyl-amino] biphenyl (α-) which is an aromatic amine material. In addition to NPD) 4,4 ′, 4 ″ -tris (N-3-methylphenyl-N-phenyl-amino) triphenylamine (MTDATA), poly (ethylenedioxythiophene) is used as a high molecular organic compound. / Poly (styrenesulfonic acid) aqueous solution) PEDOT / PSS), etc. These may be formed by vacuum deposition, spin coating, or the like.

  In addition, before forming the hole injection layer, the hole injection electrode may be heat-treated at a temperature of 100 to 300 ° C., or may be subjected to a wiping treatment or a polishing treatment in order to clean and improve flatness. good.

  The barrier layer may be difficult to form when the light-transmitting oxide conductive layer is densely formed. The barrier layer is preferably made rough to a certain degree of submicron level. That is, when forming a resist resin in close contact with the patterning of the translucent oxide conductive layer, or when forming an organic resin layer thereon, the oxide metal, silicon oxide, and carbon that are components of the translucent oxide conductive layer A barrier layer can be formed by combining a system substance.

  The light-emitting element configured as described above has the effect of the original work function of the hole injection electrode because the hole injection electrode is not in direct contact with the hole injection layer or hole transport layer, which is an organic compound. Is expressed. And the luminous efficiency can be improved by improving the hole injection efficiency with respect to a positive hole injection layer, and also aiming at effective utilization of a carrier.

  FIG. 5 shows a band model showing contact between a conventional translucent oxide conductive layer (hereinafter also referred to as “CTO”) and a hole injection layer (hereinafter also referred to as “HIL”). If the contact between CTO and HIL is not well formed, the band of the hole injection layer bends in the direction of creating a barrier against electrons due to the influence of the interface potential. As a result, holes are accumulated near the interface. At this time, the work function of the light-transmitting oxide conductive film changes (in a decreasing direction) due to the surface contamination state or the like. In such a case, the hole injection property is lowered, and the ratio of the injected holes contributing to light emission is lowered, so that the current efficiency is lowered.

  6A and 6B show a state where an insulating or semi-insulating barrier layer containing silicon or silicon oxide is formed at the interface between CTO and HIL. The barrier layer has such a thickness that carriers can be tunneled, and has a thickness of 0.5 to 5 nm. This barrier layer acts to flatten the band as shown in FIG. 6A or bend downward as shown in FIG. 6B so that holes do not accumulate. Due to this action, the hole injection property is improved. In addition, it is possible to increase the rate at which the injected holes contribute to light emission.

  Next, a method for manufacturing a light-emitting device using the light-emitting element of the present invention will be described with reference to FIGS. First, FIG. 1A shows a transistor 101 formed over an element substrate 100. The transistor 101 corresponds to a driving transistor for supplying current to a light-emitting element to be formed later. The transistor 101 is covered with a first interlayer insulating film 103 and a second interlayer insulating film 104. The transistor 101 is connected to wirings 105 and 106 formed in contact with the second interlayer insulating film 104 through contact holes formed in the first interlayer insulating film 103 and the second interlayer insulating film 104.

  As the first interlayer insulating film 103, an organic resin film, an inorganic insulating film, an insulating film including a Si—O bond and a Si—CHx crystal formed using a siloxane-based material as a starting material, or the like can be used. The second interlayer insulating film 104 is formed of a film that hardly transmits moisture and oxygen. For example, a silicon nitride film formed by an RF sputtering method can be used. In addition, a diamond-like carbon (DLC) film, an aluminum nitride film, or the like can be used.

  When the wirings 105 and 106 are formed, a hole injection electrode 107 is formed. The hole injection electrode 107 can be formed using a light-transmitting oxide conductive film. Preferably, the hole injection electrode 107 is formed of indium tin oxide containing silicon oxide (hereinafter also referred to as “ITSO”) by a sputtering method using a target containing 2 to 10 wt% of silicon oxide in ITO. In addition to ITSO, a transparent conductive film such as a light-transmitting oxide conductive film containing silicon oxide and indium oxide mixed with 2 to 20% zinc oxide (ZnO) may be used.

  The hole injection electrode 107 may be polished by a CMP method so that the surface thereof is planarized. After polishing using the CMP method, the surface of the hole injection electrode 107 may be subjected to ultraviolet irradiation, oxygen plasma treatment, or the like. Moreover, you may wipe with a polyvinyl alcohol-type porous body. By performing such treatment, the projection of the hole injection electrode 107 can be eliminated, and the short circuit failure of the light emitting element can be eliminated. In addition, foreign matters remaining on the hole injection electrode 107 can be effectively removed.

  Next, as illustrated in FIG. 1B, a partition wall 108 is formed so as to cover the wirings 105 and 106, the second interlayer insulating film 104, and part of the hole injection electrode 107. As the partition wall 108, an organic insulating film, an inorganic insulating film, an insulating film including a Si—O bond formed using a siloxane-based material and a Si—CHx crystal hand, or the like can be used. The partition wall 108 has an opening 117, and the hole injection electrode 107 is partially exposed in the opening.

  Moreover, it is desirable to form the end part in the opening part of the partition 108 in the shape of a curved surface. That is, by making the opening end portion of the partition wall 108 a continuous gentle curved surface, the coverage of the organic compound layer 109 can be improved at that portion. The curvature of the curved surface may change continuously, but the radius of curvature is preferably in the range of 0.2 to 2 μm. With the above structure, the coverage of the organic compound layer 109 formed over the partition wall 108 can be improved. As a result, the electron injection electrode formed on the hole injection electrode 107 and the organic compound layer 109 can be prevented from being short-circuited. Further, by relaxing the stress of the organic compound layer 109, a defect called “shrink” in which a light emitting region is reduced can be reduced, and reliability can be improved.

  Note that FIG. 1B illustrates an example in which the partition 108 is formed using a positive photosensitive acrylic resin. In this case, a negative organic resin may be used. For example, when the partition 108 is formed using negative acrylic, the cross-sectional shape in the opening is a gently curved surface. The curved surface shape is preferably a shape in which the radius of curvature continuously changes. At this time, it is desirable that the radius of curvature at the upper end and the lower end of the opening is 0.2 to 2 μm.

The partition wall 108 is heated in a vacuum atmosphere in order to remove adsorbed moisture, oxygen, and the like before the organic compound layer 109 is formed. Specifically, heat treatment is performed in a vacuum atmosphere at 100 ° C. to 200 ° C. for about 0.5 to 1 hour. Desirably, the atmosphere in the heat treatment is 4 × 10 ⁻⁵ Pa or less, and if possible, it is most desirably 4 × 10 ⁻⁶ Pa or less. By performing the heat treatment under reduced pressure, the adsorbed moisture, oxygen, and the like can be removed more effectively. And when forming an organic compound layer after heat-treating an organic insulating film in a vacuum atmosphere, the reliability can be further enhanced by maintaining the vacuum atmosphere until just before the film formation.

  Between the formation of the hole injection electrode 107 and the formation of the organic compound layer, an oxidation reaction is promoted by ultraviolet irradiation or oxygen plasma treatment to form a barrier layer on the surface of the hole injection electrode 107. it can. For example, a barrier layer can be formed by ultraviolet irradiation or oxygen plasma treatment of a resist resin component and a hole injection electrode 107 component that are formed in close contact with each other when the hole injection electrode 107 is patterned. When the partition 108 is formed on the hole injection electrode 107, a barrier layer can be formed on the surface of the hole injection electrode 107 in the same manner.

  Next, as shown in FIG. 1C, an organic compound layer 109 and an electron injection electrode 110 are sequentially formed over the hole injection electrode 107. The organic compound layer 109 has a structure in which a light emitting layer alone or a plurality of layers including a light emitting layer are stacked.

  For example, the organic compound layer 109 can be formed by appropriately stacking a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. The hole injection layer can be selected from a metal oxide, a low molecular organic compound, and a high molecular compound using a material having a small ionization potential. As the metal oxide, vanadium oxide, molybdenum oxide, ruthenium oxide, aluminum oxide, or the like can be used. As the low molecular organic compound, a starburst amine typified by m-MTDATA, metal phthalocyanine typified by CuPc, or the like can be used. On the other hand, as the polymer compound material, conjugated polymers such as polyaniline and polythiophene derivatives can be used. By using these materials as the hole injection layer, the hole injection barrier is reduced, and holes can be efficiently injected into the organic compound layer formed on the light emitting layer side.

  As the hole transport layer, typically, an aromatic amine can be used. For example, 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (hereinafter referred to as α-NPD), 4,4 ′, 4 ″ -tris (N, N -Diphenyl-amino) -triphenylamine (hereinafter referred to as TDATA) and the like can be used. On the other hand, as the polymer material, poly (vinyl carbazole) or the like showing good hole transport properties may be used.

As the light emitting layer, tris (8-quinolinolato) aluminum (hereinafter referred to as Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (hereinafter referred to as Almq ₃ ), bis (10-hydroxybenzo [η]). -Quinolinato) beryllium (hereinafter referred to as BeBq ₂ ), bis (2-methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (hereinafter referred to as BAlq), bis [2- (2-hydroxyphenyl) ) -Benzoxazolate] zinc (hereinafter referred to as Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) -benzothiazolate] zinc (hereinafter referred to as Zn (BTZ) ₂ ) In addition, various fluorescent dyes are effective. Phosphorescent materials such as platinum octaethylporphyrin complex, tris (phenylpyridine) iridium complex, and tris (benzylideneacetonato) phenanthrene europium complex are also effective. In particular, phosphorescent materials have a longer excitation lifetime than fluorescent materials, so it is easy to create an inversion distribution, that is, a state with more molecules in the excited state than in the ground state, which is essential for laser oscillation. become.

  Note that in the light-emitting layer described above, a light-emitting material may be added as a guest material. That is, a material having a larger ionization potential and a larger band gap than the light emitting material may be used as a host, and a small amount (about 0.001% to 30%) of the above light emitting material may be mixed therewith.

As the electron transporting layer, a metal complex having a quinoline skeleton or a benzoquinoline skeleton represented by a tris (8-quinolinolato) aluminum complex (hereinafter referred to as Alq ₃ ) or a mixed ligand complex thereof is preferable. In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (hereinafter referred to as PBD), 1,3-bis [ Oxadiazole derivatives such as 5- (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (hereinafter referred to as OXD-7), 3- (4-tert-butyl Phenyl) -4-phenyl-5- (4-biphenylyl) -1,2,4-triazole (hereinafter referred to as TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl)- Triazole derivatives such as 5- (4-biphenylyl) -1,2,4-triazole (hereinafter referred to as p-EtTAZ), bathophenanthroline (hereinafter referred to as BPhen), bathocuproin (hereinafter referred to as “p-EtTAZ”) Shown as BCP) can be used phenanthroline derivatives such as.

  The electron injection layer may be made of an alkali metal or alkaline earth metal salt such as calcium fluoride, lithium fluoride or cesium bromide. It is good also as the structure included.

  The electron injection electrode 110 can be formed by a vapor deposition method using other known materials as long as the conductive film has a low work function. For example, Ca, Al, CaF, MgAg, AlLi, etc. are desirable. In the opening of the partition wall 108, the light emitting element 111 is formed in a region where the hole injection electrode 107, the organic compound layer 109, and the electron injection electrode 110 overlap.

  Note that when the electron injection electrode 110 is formed, a protective film may be formed so as to cover the light emitting element 111. In this case, the protective film is formed of a film that hardly transmits a substance that causes deterioration of the light-emitting element such as moisture or oxygen as compared with other insulating films. Typically, it is desirable to use, for example, a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like. In addition, the above-described film that does not easily transmit a substance such as moisture or oxygen and a film that easily allows a substance such as moisture or oxygen to pass therethrough can be stacked and used as a protective film.

  Then, it is preferably packaged (encapsulated) with a protective film (laminate film, ultraviolet curable resin film, etc.) or a light-transmitting sealing substrate that has high air tightness and little outgassing so as not to be exposed to the outside air.

  As described above, a light-emitting device that can extract light from the light-emitting element 111 on the element substrate 100 side can be obtained.

  FIG. 7 is a cross-sectional view of a light emitting device including a pixel portion having pixels (A), pixels (B), and pixels (C) having different emission colors. The pixel (A) of the element substrate 100 has a light emitting element 111a connected to the transistor 101a, the pixel (B) has a light emitting element 111b connected to the transistor 101b, and the pixel (C) has a light emitting element 111c connected to the transistor 101c. Is provided.

The structures of the transistor and the light emitting element are the same as those in FIG. A first interlayer insulating film and a second interlayer insulating film are formed between the transistors 101a to 101c and the light emitting elements 111a to 111c. The hole injection electrodes 107 a to 107 c are formed on the second interlayer insulating film 104. Second interlayer insulating film 104 is formed of a silicon nitride film or a silicon nitride oxide film. The hole injection electrode 107a is connected to the transistor 101a. The hole injection electrode 107b is connected to the transistor 101b. The hole injection electrode 107c is connected to the transistor 101c.

  The light emitting element 111a is formed by sandwiching an organic compound layer 109a between the hole injection electrode 107a and the electron injection electrode 110. The light emitting element 111b is formed by sandwiching an organic compound layer 109b between the hole injection electrode 107b and the electron injection electrode 110. The light emitting element 111c is formed by sandwiching an organic compound layer 109c between the hole injection electrode 107c and the electron injection electrode 110. The structure of the organic compound layer 109 can be formed in accordance with the emission color of each pixel, but the hole injection layer, the hole transport layer, the electron transport layer, and the electron transport layer other than the light emitting layer are common. You may make it.

  A sealing substrate 120 is provided to face the light emitting elements 111a to 111c. A resin may be filled between the sealing substrate 120 and the element substrate 100, or a dry inert gas or a reduced pressure state may be used. The transistors 101a to 101c can be formed using thin film transistors. In addition, a MOS transistor formed on a single crystal semiconductor substrate or an SOI (Silicon On Insulator) substrate, or a thin film transistor using an amorphous semiconductor film such as silicon may be used.

  FIG. 8 shows a light emitting device in which the element substrate 10 and the counter substrate 11 are integrated. FIG. 8A is a perspective view illustrating a configuration of a light emitting device excluding an external circuit and the like. FIG. 8B is a longitudinal sectional view taken along line A-A ′, and FIG. 8C is a longitudinal sectional view taken along line B-B ′.

  As shown in these drawings, the light emitting device includes an element substrate 10 provided with an image display unit 12, a scanning line driving circuit 13, a data line driving circuit 14, an input terminal unit 15, and the like, and a color filter 18. The counter substrate 11 is fixed by a sealing material 19.

  The element substrate 10 is made of glass, quartz, plastic, or the like. The counter substrate 11 is made of glass, quartz, plastic, metal or the like as a member. The substrate may be in the form of a plate, a film, or a sheet, and may have any structure of a single layer structure or a laminated structure. The glass is preferably a transparent glass such as a commercially available alkali-free glass, and an alkali glass whose surface is covered with a silicon oxide film can also be applied. When plastic is used, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethersulfone (PES), translucent polyimide, or the like can be used. In addition, transparent ceramics such as translucent alumina and ZnS sintered body can also be applied.

  The sealing material 19 is formed along the peripheral portion of the counter substrate 11, but is formed so as to overlap with the scanning line driving circuit 13 and the data line driving circuit 14 through the interlayer insulating film 16 in the positional relationship with the element substrate. Has been. The interlayer insulating film 16 is formed with a flat surface, but the outermost surface and side surfaces are formed of silicon nitride or silicon oxynitride.

  The image display unit 12 is formed in a matrix form by scanning lines and data lines extending from the scanning line driving circuit 13 and the data line driving circuit 14. The pixel matrix is formed of switching element groups arranged appropriately at various places and an organic light emitting element group 17 electrically connected to the switching element groups. The scanning line driving circuit 13 is configured to be driven from both sides of the image display unit 12. However, when signal delay is not a problem, only one side may be used.

  An input terminal portion 15 is formed on the outer peripheral portion of the element substrate 10, and various signals are input from an external circuit and are connected to a power source. The space surrounded by the element substrate 10 and the counter substrate 11 and the sealing material 19 is filled with an inert gas to prevent the organic light emitting element group 17 from being corroded. This space may contain a desiccant such as barium oxide.

  FIG. 9 is a top view showing the configuration of the element substrate 10 in more detail. The scanning line driving circuit 13 surrounding the two sides of the image display unit 12, the data line driving circuit 14 adjacent to the other side, and the input terminal unit. 15 arrangements are shown.

  The partitioned area 23 for one pixel shown in the image display unit 12 is arranged in a matrix, and can be divided into a row arrangement direction and a column arrangement direction for convenience. The first auxiliary wiring 20 is formed in a stripe shape in a direction parallel to the column arrangement direction, and both ends or one end thereof extend to the outside of the image display unit. The first auxiliary wiring 20 is formed at a position that does not overlap the region 23 for one pixel, and consideration is given so as not to impair the aperture ratio. The second auxiliary wiring 21 electrically connected to the first auxiliary wiring 20 extends in a direction parallel to the row arrangement direction, and is electrically connected to the wiring 22 extending from the input terminal portion 15 at both ends or one end thereof. ing. A constant potential or an alternating potential may be applied as the potential of the wiring 22 by the driving method of the organic light emitting element.

The auxiliary wiring is preferably formed of a material having a resistivity of 1 × 10 ⁻⁵ Ωcm or less. The resistance value per 1 cm of the auxiliary wiring is desirably 100Ω or less. Of course, the resistance value of the auxiliary wiring is determined by the line width and thickness in addition to the material to be formed. For example, when the pitch between the pixel columns is formed at 200 μm, if the width of the pixel electrode is approximately 120 μm, the width of the first auxiliary wiring formed on the partition layer is appropriately 20 to 40 μm. It is. When this is formed by using an aluminum alloy having a resistivity of 4 × 10 ⁻⁶ Ωcm and a thickness of 0.4 μm, it becomes 50 Ω per cm when the line width is 20 μm.

  In the above light emitting device, the hole injection electrode and the hole injection layer are not in direct contact with each other, so that the original work function effect of the hole injection electrode is exhibited, and the hole injection efficiency with respect to the hole injection layer is improved. Can be improved and the light emission characteristics can be improved.

  As electronic devices including the above light-emitting devices, television devices (also simply referred to as televisions or television receivers), digital cameras, digital video cameras, mobile phones, PDAs and other portable information terminals, game machines, computers Monitor, computer, sound reproduction device such as car audio, game machine and the like. One example thereof will be described with reference to FIG.

  A portable information terminal illustrated in FIG. 10A includes a display portion 202 and the like in part of a main body 201. When the display portion 202 is formed using the light-emitting device of this embodiment, a bright display portion can be formed and power consumption of the portable information terminal can be reduced.

  In the digital video camera shown in FIG. 10B, a display portion 204 is incorporated in a main body 203. When the display portion 204 is formed using the light-emitting device of this embodiment, a bright display portion can be formed and power consumption of the digital video camera can be reduced.

  In the cellular phone illustrated in FIG. 10C, a display portion 206 is incorporated in a main body 205. When the display portion 206 is formed using the light-emitting device of this embodiment, a bright display portion can be formed, power consumption of the mobile phone can be reduced, and the mobile phone can be used for a long time.

  In the game machine shown in FIG. 10D, a display portion 208 is incorporated in a main body 207. This game machine can be connected to an Internet line by wireless communication to download a program such as game software, or can communicate with other game machines to acquire various information. When the display portion 208 is formed using the light-emitting device of this embodiment, a bright display portion can be formed, power consumption of the game machine can be reduced, and the display device can be used for a long time.

  A computer illustrated in FIG. 10E includes a main body 209 and a display portion 210. By forming the display portion 210 with the light-emitting device of this embodiment, a bright screen can be formed and the power consumption of the computer can be reduced.

  A television device illustrated in FIG. 10F includes a display portion 212 in a main body 211. When the display portion 212 is formed using the light-emitting device of this embodiment, a bright screen can be formed, power consumption of the television device can be reduced, and heat generation can be suppressed.

  A light-emitting device manufactured in this example will be described with reference to FIGS. The first interlayer insulating film 103 was formed of a silicon oxynitride film, and a total of 230 nm was formed by laminating a 30 nm first silicon oxynitride film and a 200 nm second silicon oxynitride film by plasma CVD. The second interlayer insulating film 104 was formed of a silicon nitride film, and was formed to a thickness of 100 nm by sputtering using silicon as a target.

The hole injection electrode 107, using a composition ratio of indium oxide (In ₂ O ₃₎ 85 wt%, tin oxide (SnO ₂₎ 10 wt%, silicon oxide (SiO ₂₎ 5 wt% of the target (934 × 158 mm) Then, 120 SCCM of Ar and 5 SCCM of oxygen were introduced as sputtering gases, a pressure of 0.26 Pa and direct current power of 3.3 kW were introduced, and an ITSO film having a thickness of 110 nm was formed by sputtering. The ITSO film was patterned into a predetermined shape through an optical exposure process to form a hole injection electrode 107. After removing the photoresist mask, heat treatment was performed at 200 ° C. for 60 minutes using an oven.

  The partition wall 108 was formed to a thickness of 1500 nm using a photosensitive acrylic resin. After the acrylic resin was spin-coated, baking was performed at an atmospheric temperature of 85 ° C. and a processing time of 170 seconds. Thereafter, a partition wall 108 was formed by patterning into a predetermined shape through a light exposure process. Thereafter, heat treatment was performed at 220 ° C. for 60 minutes using an oven.

  Thereafter, an ultraviolet (UV) irradiation treatment was performed using a mercury lamp as a light source. Then, an organic compound layer was formed by heat treatment at 150 ° C. for 30 minutes under reduced pressure. The organic compound layer 109 includes CuPc (20 nm) as a hole injection layer, α-NPD (40 nm) as a hole transport layer, Alq3: DMQd (375 nm) (DMQd: quinacridone derivative) as a light emitting layer, and Alq3 (as an electron transport layer). 375 nm).

As the electron injection electrode 110, calcium fluoride (CaF ₂ ) was formed to a thickness of 1 nm, and a 200 nm Al film was further stacked to form the light emitting element 111.

(Comparative example)
As a comparative example, a light emitting device in which the hole injection electrode 107 was formed of ITO was manufactured. The organic compound layer 109 and the electron injection electrode 110 were configured in the same manner as in Example 1.

  FIG. 2 shows the display inspection results of the light emitting devices of this example and the comparative example. This light emitting device has 112200 pixels (the size of one pixel is 32 × 140 μm), and evaluates the luminance with respect to the current when all the pixels are energized to emit light. As shown in FIG. 2, the ratio of luminance to current (current efficiency) is significantly higher in the sample of this example using ITSO as the hole injection electrode.

  FIG. 3 shows the results of other samples produced in the same manner, and shows the display inspection results of the light emitting devices of this example and the comparative example. The table shown in FIG. 3 shows the production lot number, the position of the panel taken out from the substrate, the current, and the luminance. The sample of this example using ITSO as the hole injection electrode, regardless of which sample is compared. The ratio of luminance to current (current efficiency) is higher. FIG. 4 shows the ratio of luminance to current (arbitrary scale) for 16 samples, but the samples of this example using ITSO as the hole injection electrode in all samples were compared using ITO. Results that are 1.47 times higher on average than the example samples are obtained.

  As described above, according to the light emitting device of the present invention, high current efficiency can be obtained.

It is a figure explaining the manufacturing method of the light-emitting device using the light emitting element of this invention. It is a figure which shows the display test result of the light-emitting device of a present Example and a comparative example. It is a figure which shows the display test result of the light-emitting device of a present Example and a comparative example. It is a graph which shows the display test result of the light-emitting device of a present Example and a comparative example, and shows the ratio (arbitrary scale) of the brightness | luminance with respect to an electric current. It is a figure which shows the band model which shows the contact state of the conventional translucent oxide conductive layer and a hole injection layer. It is a figure which shows the band model explaining the state by which the insulating or semi-insulating barrier layer containing silicon or silicon oxide was formed in the interface of a translucent oxide conductive layer and a hole injection layer. It is sectional drawing of the light-emitting device provided with the pixel part which has a pixel (A) from which luminescent color differs, a pixel (B), and a pixel (C). It is a figure which shows the light-emitting device which integrated the element substrate and the counter substrate. It is a top view which shows the structure of an element substrate in detail. It is a figure explaining an example of the electronic device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Element substrate 11 Counter substrate 12 Image display part 13 Scan line drive circuit 14 Data line drive circuit 15 Input terminal part 16 Interlayer insulation film 17 Organic light emitting element group 18 Color filter 19 Seal material 20 1st auxiliary wiring 21 2nd auxiliary wiring 22 Wiring 23 region 100 element substrate 101 transistor 101a transistor 101b transistor 101c transistor 103 interlayer insulating film 104 interlayer insulating film 105 wiring 105 wiring 107 hole injection electrode 107a hole injection electrode 107b hole injection electrode 107c hole injection electrode 108 partition wall 109 organic Compound layer 109a Organic compound layer 109b Organic compound layer 109c Organic compound layer 110 Electron injection electrode 111 Light emitting element 111a Light emitting element 111b Light emitting element 111c Light emitting element 117 Opening 120 Sealing substrate 201 Main body 202 Display 203 body 204 display unit 205 body 206 display unit 207 body 208 display unit 209 body 210 display unit 211 body 212 display unit

Claims (11)

Insulating property in which a tunnel current flows between a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound, or A light-emitting element, wherein a semi-insulating barrier layer is provided. Improves hole injection efficiency between a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound An insulating or semi-insulating barrier layer is provided. A tunnel current flows so that a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide is not in close contact with a hole injection layer or a hole transport layer formed of an organic compound. A light-emitting element provided with an insulating or semi-insulating barrier layer. Hole injection so that a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide is not in close contact with a hole injection layer or a hole transport layer formed of an organic compound. A light-emitting element having an insulating or semi-insulating barrier layer for improving efficiency. The surface of the hole injection electrode is formed between a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide and a hole injection layer or a hole transport layer formed of an organic compound. And a barrier layer containing silicon or silicon oxide. The hole injection electrode is formed so that a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide is not in close contact with a hole injection layer or a hole transport layer formed of an organic compound. A light-emitting element, wherein a barrier layer containing silicon or silicon oxide is provided on a surface of an electrode. 7. The translucent oxide conductive layer according to claim 1, wherein the translucent oxide conductive layer is one selected from indium tin oxide, zinc oxide, indium zinc oxide, and zinc oxide to which gallium is added. Light emitting element. An insulating or semi-insulating barrier layer through which a tunnel current flows is formed on the surface of a hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide, and an organic compound is formed on the barrier layer. A method for manufacturing a light-emitting element, comprising: forming a hole injection layer or a hole transport layer formed by the step. An insulating or semi-insulating barrier layer for improving the hole injection efficiency is formed on the surface of the hole injection electrode formed of a light-transmitting oxide conductive layer containing silicon or silicon oxide, and the barrier layer is formed on the barrier layer. And forming a hole injection layer or a hole transport layer formed of an organic compound. A barrier layer formed by selectively removing the indium tin oxide and leaving the silicon or silicon oxide on the surface of a hole injection electrode formed of silicon or indium tin oxide containing silicon oxide is formed. A method for manufacturing a light-emitting element, comprising forming a hole injection layer or a hole transport layer formed of an organic compound on the barrier layer. A conductive layer of a light-transmitting oxide conductive layer containing silicon or silicon oxide is formed on an insulating surface, a photosensitive organic resin material is applied on the conductive layer, and then exposed to remove non-photosensitive portions. And developing an organic resin layer having an opening through which the conductive layer is exposed, and forming a hole injection layer formed of an organic compound on the conductive layer after the heat treatment. A method for manufacturing a light-emitting element.

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