JP2012256553A - Transparent conductive film for organic el and organic el element including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a transparent conductive film for organic EL, with which a low contact resistance with an anode made of Al or an Al alloy can be obtained and a favorable transmittance in a short wavelength region can be obtained; and an organic EL element including the transparent conductive film.SOLUTION: A transparent conductive film 1 for organic EL is formed between an electroluminescent layer 2 and a metal film 3 made of Al or an Al alloy in an organic EL element 10. The transparent conductive film 1 comprises an Al-Mg-Zn-based oxide in which the content ratios of metal component elements are, by atomic ratio, Al: 0.7-7% and Mg: 10-25%, with the balance of Zn.

Description

  The present invention relates to a transparent conductive film used in an organic electroluminescence (EL) display device and an organic EL element using the transparent conductive film.

  In general, in an organic EL display device, an anode (anode) and a cathode (cathode) are arranged on both sides of an electroluminescent layer including an organic EL layer on a TFT active matrix substrate on which TFTs (thin film transistors) as switching elements are arranged. The organic EL element thus formed is formed in each pixel region.

  Conventionally, in this organic EL device, an Al or Al alloy metal film or an Ag or Ag alloy metal film is used as the anode metal film, and ITO (Indium) is interposed between the metal film and the electroluminescent layer. A transparent conductive film such as Tin Oxide (indium tin oxide) and AZO (Aluminum doped Zinc Oxide) is provided. This transparent conductive film is provided for the purpose of preventing the sulfur (S) component contained in the electroluminescent layer from diffusing into the metal film.

JP 2006-236839 A

Kobe Steel Engineering Reports / Vol. 57 No. 1 (Apr. 2007)

The following problems remain in the conventional technology.
That is, conventionally, ITO used for the transparent conductive film between the metal film and the electroluminescent layer has a problem that contact resistance with the Al metal film is high (see Non-Patent Document 1). For this reason, when AZO that provides a low contact resistance with respect to an Al or Al alloy metal film is employed, the transmittance in the visible short wavelength region (wavelength 380 nm or less) is low with respect to the reflected light from the metal film. There was an inconvenience.

  The present invention has been made in view of the above-mentioned problems, and provides a transparent conductive film for organic EL that can obtain a low contact resistance with an Al or Al alloy metal film and a good transmittance in a short wavelength region. An object is to provide an organic EL device using a transparent conductive film.

The present invention employs the following configuration in order to solve the above problems. That is, the transparent conductive film for organic EL of the present invention is a transparent conductive film formed between an electroluminescent layer including an organic EL layer of an organic EL element and a metal film of Al or Al alloy, and is a metal component element The content ratio is made of an Al—Mg—Zn-based oxide that is Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn.
In this organic electroluminescent transparent conductive film, the content ratio of the metal component elements is from an Al—Mg—Zn-based oxide in which the atomic ratio is Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn. Therefore, by containing Al, it is possible to obtain a low contact resistance with respect to an Al or Al alloy metal film as compared with ITO, and to obtain a high transmittance in a short wavelength region as compared with AZO.

Here, the reason which limited the content rate of the metal component element in the transparent conductive film for organic EL of this invention as mentioned above is as follows.
Al:
Al is added because it has the effect of improving the conductivity of the transparent conductive film, but if its content is less than 0.7 atomic%, the effect of improving the conductivity is not sufficient, while Al is contained in excess of 7 atomic%. Doing so is not preferable because the carrier concentration increases and the transparency of the transparent conductive film decreases. Therefore, the content ratio of Al or Al alloy in all the metal component elements contained in the transparent conductive film of the present invention is set to Al: 0.7 to 7 atomic%.
Mg:
By including 10 atomic% or more of Mg as a metal component element in the transparent conductive film, the band gap can be controlled within the range of 3.5 to 4.2 eV according to the content, so that the short wavelength Transparency to light is improved. Furthermore, by adding Mg, an excessive increase in carrier concentration in the film is prevented, and transparency to near-infrared light is also improved. On the other hand, when the Mg content exceeds 25 atomic%, the conductivity of the transparent conductive film is significantly lowered in the presence of moisture and oxygen. Therefore, the Mg content in the total metal component elements is Mg: 10. It was set to ˜25 atomic%.

Moreover, the transparent electroconductive film for organic EL of the present invention further contains Ga: 0.015 to 0.085% by atomic ratio, and is made of an Al—Mg—Ga—Zn-based oxide. .
That is, in this transparent electroconductive film for organic EL, further, Ga: 0.015 to 0.085% is contained in an atomic ratio and is made of an Al—Mg—Ga—Zn-based oxide, so that Ga is added. Compared to Al-Mg-Zn-based oxide transparent conductive film, it has much better moisture resistance, and as a result, there is little increase in specific resistance due to the presence of moisture and oxygen in the usage environment, and transparent conductive film As a result, the deterioration of the film characteristics can be suppressed, and the deterioration of the element characteristics can be prevented.

Here, the reason which limited the content rate of the Ga component in the transparent conductive film for organic EL of this invention as mentioned above is as follows.
Ga:
By containing 0.015 atomic% or more of Ga as a metal component element in the transparent conductive film, the deterioration of the conductivity in a high temperature and high humidity use environment is maintained while maintaining the band gap without impairing the transparency of the film. However, if the Ga content exceeds 0.085%, the conductivity of the film (immediately after the film formation and before the high temperature and high humidity test) is lowered, and the conductivity as a transparent conductive film is insufficient. The content ratio of Ga in all metal component elements contained in the transparent conductive film was determined to be Ga: 0.015 to 0.085 atomic%.

The organic EL device of the present invention is an organic EL device comprising an anode, an electroluminescent layer including an organic EL layer formed on the anode, and a cathode formed on the electroluminescent layer, The anode includes an Al or Al alloy metal film, and the organic EL transparent conductive film of the present invention formed between the metal film and the electroluminescent layer. .
That is, in this organic EL element, since the transparent conductive film for organic EL of the present invention is formed between the Al or Al alloy metal film and the electroluminescent layer, it can be driven at a low voltage with a low contact resistance. In addition, high brightness can be obtained in a wide range including a short wavelength region due to high transparency.

The present invention has the following effects.
That is, according to the transparent electroconductive film for organic EL according to the present invention, the content ratio of the metal component elements is Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn—Al— Since it is made of an Mg—Zn-based oxide, low contact resistance can be obtained and high transmittance can be obtained in a short wavelength region. Furthermore, a trace amount of Ga is contained as a metal component element, and it is configured as an Al—Mg—Ga—Zn-based oxide transparent conductive film. As a result, it has extremely excellent moisture resistance, and as a result, there is little increase in specific resistance due to the presence of moisture and oxygen in the use environment.
Therefore, according to the organic EL device using the transparent conductive film of the present invention, it is possible to obtain good electric characteristics and high luminance in a wide wavelength region, and further suppress the deterioration of the film by containing Ga for a long time. A decrease in light emission efficiency can be suppressed over a period.

In embodiment of the transparent conductive film for organic EL which concerns on this invention, and an organic EL element provided with the same, it is typical sectional drawing which shows the structure of an organic EL element.

Hereinafter, an embodiment of a transparent conductive film for organic EL according to the present invention and an organic EL element including the same will be described with reference to FIG.
As shown in FIG. 1, the organic EL transparent conductive film 1 of the present embodiment is a transparent conductive film formed between an electroluminescent layer 2 of an organic EL element 10 and an Al or Al alloy metal film 3. Thus, the metal component element is a film made of an Al—Mg—Zn-based oxide having an atomic ratio of Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn.
Moreover, this transparent electroconductive film 1 for organic EL is a film | membrane which further contains Ga: 0.015-0.085% by atomic ratio, and consists of an Al-Mg-Ga-Zn type oxide.

  In addition, the organic EL element 10 of the present embodiment includes an anode 5 formed on the film formation substrate 4, an electroluminescent layer 2 including the organic EL layer 2 b formed on the anode 5, and the electroluminescent layer 2. An organic EL device having a cathode 6 formed thereon, wherein the anode 5 is formed between an Al or Al alloy metal film 3 and the metal film 3 and the electroluminescent layer 2. And a transparent conductive film 1 for organic EL.

For example, the electroluminescent layer 2 has a thickness of 100 to 200 nm, the organic EL transparent conductive film 1 has a thickness of 10 to 20 nm, and the metal film 3 has a thickness of 100 nm.
The electroluminescent layer 2 has a three-layer structure in which a hole (hole) transport layer 2a, an organic EL layer 2b, and an electron transport layer 2c are stacked in this order on the anode 5.

In addition, as an organic polymer material (hole injection / transport material) constituting the hole transport layer 2a, it has the ability to transport holes, and the hole injection effect from the anode 5, the organic EL layer 2b or the light emitting material. On the other hand, a compound that has an excellent hole injection effect, prevents excitons generated in the organic EL layer 2b from moving to the electron transport layer 2c, and has an excellent thin film forming ability is preferable.
Specifically, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyaryl Alkane, stilbene, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine, and their derivatives, polyvinylcarbazole, polymers such as polysilane, polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS), polymer materials such as polyaniline / camphorsulfonic acid (PANI / CSA) and other conductive polymers And the like.

Examples of the light emitting material used for the organic EL layer 2b include olefin-based light emitting materials such as 4,4 ′-(2,2-diphenylvinyl) biphenyl, 9,10-di (2-naphthyl) anthracene, and 9,10−. Bis (3,5-diphenylphenyl) anthracene, 9,10-bis (9,9-dimethylfluorenyl) anthracene, 9,10- (4- (2,2-diphenylvinyl) phenyl) anthracene, 9,10 '-Bis (2-biphenylyl) -9,9'-bisanthracene, 9,10,9', 10'-tetraphenyl-2,2'-bianthryl, 1,4-bis (9-phenyl-10-anthracenyl) ) Anthracene-based luminescent materials such as benzene, spiro-based luminescent materials such as 2,7,2 ′, 7′-tetrakis (2,2-diphenylvinyl) spirobifluorene, 4,4′-dica Carbazole-based light-emitting materials such as bazolylbiphenyl and 1,3-dicarbazolylbenzene, low-molecular light-emitting materials represented by pyrene-based light-emitting materials such as 1,3,5-tripyrenylbenzene, polyphenylene vinylenes, Examples thereof include polymer light-emitting materials such as polyfluorenes and polyvinylcarbazoles.
The organic EL layer 2b may be doped with a fluorescent dye or a phosphorescent dye.

  The electron injecting / transporting material used for the electron transporting layer 2c has the ability to transport electrons, has an electron injecting effect from the cathode 6, and has an excellent electron injecting effect with respect to the organic EL layer 2b or the light emitting material. A compound that prevents migration of excitons generated in the EL layer 2b to the hole injection layer and that has an excellent thin film forming ability is preferable. Specifically, for example, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, anthrone and the like And derivatives thereof.

The organic EL transparent conductive film 1 has an atomic ratio of an oxide sputtering target composed of Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn in terms of atomic ratio, or Al: 0. A film can be formed by DC sputtering or pulse DC sputtering of an oxide sputtering target composed of 0.7 to 7%, Mg: 10 to 25%, Ga: 0.015 to 0.085%, and the balance Zn. .
The organic EL transparent conductive film 1 has a specific resistance of about 1 × 10 ⁻³ Ω · cm.

Here, the technical reason for determining the component composition of the sputtering target as described above is as follows.
Al:
Al has an effect of improving the carrier density and hole movement amount of the transparent conductive film obtained by sputtering and improving the conductivity of the film, so it is contained in an amount of 0.7 atomic% or more, but the content is 0. Even if it is less than 7 atomic% or more than 7 atomic%, it is not preferable because the conductivity of the transparent conductive film is lowered. Therefore, Al contained in this transparent conductive film forming sputtering target is set to 0.7 to 7 atomic%.

Mg:
Mg is effective in adjusting the band gap of the transparent conductive film obtained by sputtering and improving the transparency with respect to light having a short wavelength and the transparency with respect to light having a near infrared wavelength. If the Mg content is less than 10 atomic%, the effect of adjusting the band gap cannot be obtained sufficiently, and the effect of improving the transparency of the film for short wavelengths is insufficient. When the Mg content exceeds 25 atomic%, the conductivity of the film is significantly lowered. Therefore, Mg contained in the sputtering target for forming a transparent conductive film is set to 10 to 25 atomic%.

Ga:
Ga is effective in improving the moisture resistance of the transparent conductive film. When the Ga content is less than 0.015 atomic%, the moisture resistance of the film is insufficiently improved. On the other hand, when the Ga content exceeds 0.085 atomic%, the electrical resistance of the film is remarkably increased. . Therefore, Ga contained in this transparent conductive film forming sputtering target is set to 0.015 to 0.085 atomic%.

  In addition, the oxide sputtering target which the content rate of a metal component element consists of Al: 0.7-7%, Mg: 10-25%, Ga: 0.015-0.085%, and remainder Zn is atomic ratio. Since the bulk resistance of the target can be suppressed to 0.1 Ω · cm or less, a high-quality transparent conductive film can be formed at high speed by DC or pulse DC sputtering.

  This transparent conductive film-forming sputtering target can be produced, for example, by the following method. Here, as an example, an example of a method for manufacturing an oxide sputtering target in the case of containing Ga will be described.

First, as a raw material powder, a purity of 99.9% or more and an average primary particle diameter of 5 μm or less of Al ₂ O ₃ powder, MgO powder, Ga ₂ O ₃ powder and ZnO powder are weighed and blended to have a predetermined composition, After the average particle size is pulverized to 0.1 to 3.0 μm by a wet ball mill, it is vacuum dried at 80 ° C. for 5 hours. Next, the dried mixed powder is filled into a graphite mold and hot pressed in a vacuum at a temperature of 700 to 1300 ° C. for 0.5 to 5 hours under a pressure of 100 to 350 kgf / cm ^2. Thus, a sputtering target for forming a transparent conductive film can be produced.

Preferred sputtering conditions for performing sputtering are, for example, as follows.
First, the relative density of the sputtering target is preferably 90% or more. When the relative density is less than 90%, the film formation rate is lowered and the film quality of the obtained film is lowered. The relative density of the sputtering target is more preferably 95% or more, and particularly preferably 97% or more.
Note that the purity of the sputtering target is preferably 99% or more. If the purity is less than 99%, the conductivity and chemical stability of the resulting film are reduced due to impurities. Furthermore, the purity of the sputtering target is more preferably 99.9% or more, and particularly preferably 99.99% or more.

  Further, in performing sputtering using the above-described sputtering target, first, a film-forming substrate (hereinafter referred to as “film-forming substrate”) and a sputtering target are mounted in a vacuum chamber of the sputtering apparatus, and the apparatus and film-forming are performed. It is desirable to remove moisture adsorbed on the substrate, sputtering target, and the like.

The removal of the water can be performed, for example, by evacuating until the ultimate vacuum pressure of the vacuum chamber is 5 × 10 ⁻⁴ Pa or less. Heating is preferably performed during evacuation, and this heating makes it possible to more reliably remove moisture and shorten the time for evacuation. If the ultimate vacuum pressure at this time does not reach 5 × 10 ⁻⁴ Pa or less, the removal of moisture adsorbed on the apparatus, the film formation substrate, the sputtering target, etc. tends to be insufficient. Lowers and affects the conductivity and moisture resistance of the film. Note that the exhaust system of the sputtering apparatus to be used preferably has a trap or getter for removing moisture.

After performing the above-described vacuum evacuation, a transparent conductive film is formed. The degree of vacuum during film formation is preferably 1 × 10 ⁻² to 1 × 10 ⁰ Pa. When the sputtering gas pressure is less than 1 × 10 ⁻² Pa (lower than 1 × 10 ⁻² Pa), the discharge stability during film formation is reduced, and when it exceeds 1 × 10 ⁰ Pa, the voltage applied to the sputtering target is increased. It becomes difficult to do. The sputtering gas pressure during film formation is particularly preferably 0.1 to 1 × 10 ⁰ Pa.
The direct current output during film formation is preferably 1 W / cm ² or more and 10 W / cm ² or less. If this output exceeds 10 W / cm ² , the denseness of the resulting film will be reduced, making it difficult to obtain a highly moisture-resistant transparent conductive film. The output during film formation is more preferably 3 to 8 W / cm ² . The voltage during film formation is preferably 100 to 400V.

As the atmospheric gas during the film formation, a sufficient highly transparent film is usually obtained only with argon gas (Ar gas), but a mixed gas of argon gas (Ar gas) and oxygen gas (O ₂ gas) is used. It is also possible. The mixing ratio of Ar gas and O ₂ gas varies depending on the oxidation state of the sputtering target to be used, the degree of vacuum at the time of film formation, and the output, but when the volume concentration of O ₂ gas in the atmospheric gas exceeds 5%, it is obtained. The conductivity of the resulting film tends to decrease. Therefore, the volume concentration of O ₂ gas in the atmospheric gas during film formation is preferably 5% or less, and more preferably 3% or less.

  The substrate temperature at the time of film formation can be appropriately selected within the range of 50 ° C. to the heat resistant temperature of the film formed substrate, but if the substrate temperature exceeds 200 ° C., many resin substrates will exceed the heat resistant temperature. The types of substrates that can be made are severely limited. Further, if the substrate temperature is less than 50 ° C., the denseness of the resulting film is lowered and it becomes difficult to obtain a highly moisture-resistant transparent conductive film. Therefore, the substrate temperature during film formation should be 50 to 200 ° C. Preferably, it is 80-200 degreeC, It is more preferable to set it as 100-200 degreeC.

For example, when an organic EL element is formed on a TFT substrate, the film formation substrate 4 is a glass substrate or a heat resistant resin substrate on which a plurality of insulating films such as a SiN film or a SiO ₂ film serving as a gate insulating film are stacked. An insulating substrate such as is used.

Thus, in the transparent electroconductive film 1 for organic EL of this embodiment, the content ratio of the metal component elements is Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn—Al— Since it is made of an Mg-Zn-based oxide, it can have a lower contact resistance with respect to the metal film 3 of Al or Al alloy than ITO by containing Al, and is higher in a short wavelength region than AZO. Transmittance is obtained.
In the organic EL element 10 of the present embodiment, since the organic EL transparent conductive film 1 is formed between the Al or Al alloy metal film 3 and the electroluminescent layer 2, a low voltage due to a low contact resistance. And can be driven at a high luminance in a wide range including a short wavelength region due to high transparency.

  Examples of the transparent conductive film for organic EL actually formed on the basis of the present embodiment will be described below.

First, preparation of a sputtering target for forming a transparent conductive film for organic EL of the present invention containing Ga will be described.
As the raw material powder, an Al ₂ O ₃ raw material powder having a purity of 99.9% or more and an average particle size of 0.4 μm, an MgO raw material powder having a purity of 99.9% or more and an average particle size of 1 μm, a purity of 99.9% or more and an average particle size of 0.003. A 3 μm Ga ₂ O ₃ raw material powder and a ZnO raw material powder having a purity of 99.9% or more and an average particle diameter of 0.4 μm are weighed and blended so as to have a predetermined composition shown in Table 1. The blended powder is put into a polyethylene pot and ball milled using zirconia balls having a diameter of 3 mm, and the average primary particle size of the mixed powder is pulverized to 0.3 μm or less (note that the solvent used in the ball mill is ethanol) The slurry having reached the target average particle size is air-dried and then vacuum-dried at 80 ° C. for 5 hours.

This dried mixed powder is filled into a graphite mold and subjected to sintering with a diameter of 165 mm and a thickness of 9 mm by vacuum hot pressing under the conditions of the predetermined sintering temperature and sintering time shown in Table 1 and pressing force: 350 kgf / cm ^2. A bonded body was prepared, and then a sputtering target for forming a transparent conductive film shown in Table 1 having a diameter of 152.4 mm × thickness of 6 mm (hereinafter, shown as Examples 1 to 6) was manufactured by machining.
Next, the formulation of the raw material powder shown in Table 1, to prepare a raw material powder containing no Ga ₂ O ₃ component, in the same manner as in Example 1 to Example 6, a sputtering target of Examples 7 to 10 Produced.
Moreover, as shown in Table 1, the raw material powder was prepared so that the content of at least one of Al and Mg was outside the scope of the present invention, and Comparative Example 1 was performed in the same manner as in Examples 1 to 6 above. ˜4 sputtering targets were prepared.

For comparison, sputtering targets of Conventional Examples 1 to 3 used for forming a conventional ITO and AZO transparent conductive film for organic EL were prepared.
The AZO targets of Conventional Examples 1 and 2 are weighed and blended so as to have a predetermined composition shown in Table 1 using the same raw material powder as in the above Examples. The blended powder is put into a ball mill (bead mill) and ball milled using zirconia balls having a diameter of 1 mm, and the average primary particle diameter of the mixed powder is pulverized to 0.3 μm or less. The solvent used is water. When the target average primary particle size is reached, a binder (PVA) is added to the slurry, dry granulation is performed with a spray dryer, and a compact is produced by pressure molding with a mold. The obtained molded body was sintered in an oxygen atmosphere under the conditions shown in Table 1, and a target was prepared through mechanical polishing.

The ITO target of Conventional Example 3 shows SnO ₂ raw material powder having a purity of 99.9% or more and an average particle size of 0.3 μm, and In ₂ O ₃ raw material powder having a purity of 99.9% or more and an average particle size of 0.4 μm as shown in Table 1. Weigh and blend so as to have a predetermined composition. The pulverization, mixing, and shaping of the particles were performed in the same manner as in Examples 1 and 2. The obtained molded body was sintered in an oxygen atmosphere under the conditions shown in Table 1, and a target was prepared through mechanical polishing.

About each sputtering target of Examples 1-10 obtained above, Comparative Examples 1-4, and Conventional Examples 1-3, theoretical density ratio, specific resistance, and metal element content were calculated | required. The theoretical density ratio is the ratio between the oxide sintered body density and the theoretical density. The theoretical density is derived from the composition of the sintered body raw material and its crystal structure data when there are no defects such as vacancies. It refers to the density to be burned. The sintered body density was calculated by measuring the weight and dimensions.
Moreover, the specific resistance was calculated | required by measuring with Mitsubishi Gas Chemical's four-probe resistance measuring device Lorester. Further, the content of the metal element was obtained by collecting an analytical sample from the target and quantitatively measuring it by the ICP method (high frequency inductively coupled plasma method).
The respective values are shown in Table 1.

Next, production of a transparent conductive film for organic EL will be described.
Each of the sputtering targets of Examples 1 to 10, Comparative Examples 1 to 4, and Conventional Examples 1 to 3 was bonded to a copper backing plate using In and sputtered using a sputtering apparatus, and the organic EL materials shown in Table 2 were used. A transparent conductive film was formed.
The sputtering conditions of this example, comparative example, and conventional example in Table 2 are all the same. The ultimate vacuum pressure during sputtering was 5 × 10 ⁻⁴ Pa, the Ar gas pressure during sputtering was 0.67 Pa, and the substrate temperature was within the range of room temperature to 250 ° C. In addition, the power supply used for sputtering is a direct current (DC) power supply RPG-50 manufactured by Nippon KS Corporation. The input power density is 8 W / cm ² . The substrate used was alkali-free glass (Corning 1737 #). Table 2 shows the abnormal discharge during sputtering and the state of the target after sputtering.

  The content of the metal component element in the film was obtained by collecting the sputtered film as a sample for analysis and using inductively coupled plasma emission spectroscopic analysis (ICP method) [device used: SPS-1500VR (manufactured by Seiko Electronics Industry)]. Table 2 shows the content of metal component elements.

Furthermore, the film characteristics (light transmittance, moisture resistance) of each of the transparent conductive films of Examples, Comparative Examples, and Conventional Examples were investigated.
About the obtained transparent electroconductive film for organic EL, the film thickness is determined by a stylus method [use device: DEKTAK3030 (manufactured by Sloan)], and the specific resistance is measured by a four-probe resistance meter Lorester manufactured by Mitsubishi Gas Chemical. Sought by. The light transmittance of the film was determined by spectroscopy [applied equipment: U-3210 (manufactured by Hitachi, Ltd.)]. Table 2 shows the light transmittance at light wavelengths of 350 nm and 900 nm.

The moisture resistance of the film was evaluated in accordance with a moisture resistance test standard according to the evaluation of the organic EL element at 80 ° C. and 85% R.D. The specific resistance of the film after being left for 1000 hours in a high-temperature, high-humidity atmosphere of H was measured by measuring with a four-probe resistance measuring instrument Lorester manufactured by Mitsubishi Gas Chemical Company.
Table 3 shows each characteristic value.

Next, in order to measure contact resistance, an Al film was formed on a glass substrate by a sputtering method to a thickness of 150 nm, and a transparent conductive film having a thickness of 100 nm was formed thereon using the targets of Examples, Comparative Examples, and Conventional Examples. . Further, this laminated film was heat-treated in vacuum at 150 ° C. for 30 minutes, and then contact resistance was measured by the following TLM (Transmission Line Model) method. The contact resistance was evaluated based on whether it was 0.01 Ω · cm or more. This is because a contact resistance of 0.01 Ω · cm or more is not preferable for an organic EL device.
In the TLM method, first, electrode pairs of a plurality of ohmic electrodes having different electrode intervals are formed on a semiconductor substrate, and the electrical resistance of each electrode pair is measured. Thereafter, the measured electric resistance is plotted on the coordinates with the electrode interval as the horizontal axis and the electric resistance as the vertical axis, and from the slope of the approximate linear straight line obtained from the plotted points and the intercept. Find contact resistance.

As can be seen from the comparison of the film properties shown in Tables 3-4, Examples 1-10 all have transmittances of 90% or more at a short wavelength of 350 nm, whereas Comparative Examples 1, 2 and Conventional Examples 1-3 Is less than 90%. Furthermore, regarding the specific resistance of the film, all of Examples 1 to 10 before the moisture resistance test are 10 mΩ · cm or less, whereas all the comparative examples are 100 mΩ · cm or more. A specific resistance of 100 mΩ · cm or more is not preferable as a transparent conductive film for organic EL. Further, regarding the moisture resistance test, all the films of Examples 1 to 10 were 350 mΩ · cm or less, whereas Comparative Examples 1 and 2 and Conventional Examples 1 and 2 showed 1000 mΩ · cm or more. Also showed a higher specific resistance.
Regarding the contact resistance with the Al film, Examples 1 to 10 all show values of less than 10 ⁻² Ω · cm, whereas Comparative Examples 1 to 4 and Conventional Example 3 have values of 10 ⁻² Ω · cm or more. It is a value. A contact resistance characteristic of 10 ⁻² Ω · cm or more is not preferable as a transparent conductive film for organic EL.

  The technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.

  As described above, the transparent electroconductive film for organic EL of the present invention can obtain a low contact resistance as compared with ITO and a high transmittance in a short wavelength region as compared with AZO. Or it is suitable as a transparent conductive film on the metal film of Al alloy. That is, if the transparent electroconductive film for organic EL of the present invention is used for an organic EL element, good electric characteristics can be obtained and high luminance can be obtained in a wide wavelength region. It is expected as an element constituting a pixel of a display device.

  DESCRIPTION OF SYMBOLS 1 ... Transparent electroconductive film for organic EL, 2 ... Electroluminescent layer, 3 ... Metal film of Al or Al alloy, 4 ... Deposition substrate, 5 ... Anode, 6 ... Cathode, 10 ... Organic EL element

Claims (3)

A transparent conductive film formed between an electroluminescent layer including an organic EL layer of an organic EL element and a metal film of Al or Al alloy,
For organic EL, characterized in that the content ratio of metal component elements is an atomic ratio of Al: 0.7 to 7%, Mg: 10 to 25%, and the balance Zn: Al—Mg—Zn-based oxide. Transparent conductive film. The transparent conductive film for organic EL according to claim 1,
Furthermore, it contains Ga: 0.015-0.085% by atomic ratio, and consists of an Al-Mg-Ga-Zn type oxide, The transparent conductive film for organic EL characterized by the above-mentioned. An anode,
An electroluminescent layer including an organic EL layer formed on the anode;
An organic EL device comprising a cathode formed on the electroluminescent layer,
The anode includes a metal film of Al or an Al alloy, and the organic EL transparent conductive film according to claim 1 or 2 formed between the metal film and the electroluminescent layer. An organic EL element characterized by comprising:

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