JP7640309B2 - Method for manufacturing light-transmitting substrate with light-scattering film, and method for manufacturing organic EL panel - Google Patents

Description

The present invention relates to a method for manufacturing a light-transmitting substrate with a light-scattering film, and a method for manufacturing an organic EL panel.

Translucent substrates with light-scattering films are used as substrates for forming translucent electrode layers for organic EL elements, photoelectric conversion elements, etc., with the aim of enhancing the performance of these elements.

For example, a light-transmitting substrate with a light-scattering film for forming an organic EL element is also called a light extraction substrate and is used to improve power efficiency.

Here, an organic EL element is a surface-emitting device that utilizes the phenomenon in which light is emitted when an electric field is applied to a substance. Organic EL panels, which have organic EL elements formed on a substrate, are being developed for use in flat light sources and displays, taking advantage of their characteristics of being self-luminous and being able to be made thin.

However, organic functional materials used in the light-emitting layers of organic EL elements are easily degraded by moisture and oxygen, which can lead to the formation of dark spots and reduced luminous efficiency, so the substrate must have high barrier properties against oxygen and moisture that may penetrate from outside the element.

The light extraction substrate has the role of efficiently extracting light from the light-emitting section to the outside, and for this purpose, it is effective to provide a light scattering film to suppress total reflection caused by light moving from the high refractive index element side toward the low refractive index air. However, if an uneven layer is used as the light scattering film, unevenness will exist on the surface of the light extraction substrate that contacts the organic EL element, particularly its organic functional layer, and the power luminous efficiency of the organic EL panel will actually decrease as the performance of the element decreases, such as an increase in leakage current.

For the reasons stated above, a light-transmitting substrate with a light-scattering film generally requires not only sufficient scattering properties, but also high barrier properties and a smooth surface for forming the light-transmitting electrode layer.

Patent Document 1 relates to such a light-transmitting substrate with a light-scattering film, and has a light extraction film on a glass substrate, the light extraction film being characterized by including an amorphous matrix of a first glass material, crystallite particles dispersed in the amorphous matrix and including crystallites of the first glass material, and glass particles of a second glass material dispersed in the amorphous matrix and having a higher melting point than the first glass material, and discloses a method for efficiently extracting light from a light-emitting section to the outside.

JP 2019-175693 A

By using such a light extraction substrate as disclosed in Patent Document 1 as a raw material, the performance of the organic EL panel, particularly the luminous efficiency, is improved. However, the inventors have noticed that the surface smoothness mentioned above is insufficient and there is room for improvement. From the standpoint of reliability, particularly a longer life, they believe that a light-transmitting substrate with a light-scattering film having better characteristics, particularly a higher surface smoothness, is needed.

In other words, in organic EL panels using a light extraction substrate produced by the method described in Patent Document 1 as a raw material, the power luminous efficiency decreases due to an increase in leakage current when light emission continues, and further improvement is desired.

The inventors have found, through extensive investigation, that it is possible to solve the problems of the conventional technology in a method for manufacturing a translucent substrate with a light-scattering film for forming a translucent electrode layer, and provide a substrate that has not only sufficient scattering properties, but also high barrier properties and a higher surface smoothness for forming a translucent electrode layer. They have also found, for example, that the use of such a substrate makes it possible to produce organic EL panels with long life and high performance, which has led to the invention.

That is, the present invention provides a method for producing a light-scattering film-attached translucent substrate for forming a light-scattering electrode layer, the method comprising the steps of: a glass substrate having a film-forming surface and an opposite surface as both main surfaces; and a light-scattering film, the surface of the light-scattering film opposite to the glass substrate being a surface for forming a light-scattering electrode layer,
the light-scattering film includes a first glass material and a second glass material having a higher melting point than the first glass material;
a coating step of coating a glass paste containing the raw materials of the first glass material and the second glass material on the film-forming surface to form a coating layer; and a firing step of firing the coating layer.
The present invention relates to a method for producing a light-transmitting substrate with a light-scattering film, characterized in that the firing step includes a press firing operation in which a press member contact surface of a press member is brought into contact with a surface of the coating layer, which serves as a surface for forming the light-transmitting electrode layer, and a load is applied to the coating layer in the direction toward the glass substrate via the press member.

The surface smoothness of the surface for forming the translucent electrode layer of the substrate manufactured by the manufacturing method of the translucent substrate with a light-scattering film of the present invention depends on the smoothness of the contact surface of the press member, for example, by forming the contact surface with a preferred material described later, for example, the contact surface can be made to have sufficient surface smoothness, and by applying a load during press firing, foreign matter on the glass paste and glass particles of the second glass material with a higher melting point than the first glass material are pushed into the glass paste as firing progresses, resulting in a satisfactory surface smoothness of the light-scattering film. For example, an organic EL panel using a substrate manufactured by this method as a raw material has low leakage current without a decrease in power luminous efficiency.

The firing step is carried out in the following order:
The press member contact surface is not brought into contact with the surface of the coating layer, and
Exposing the surface of the coating layer to a baking atmosphere at a baking temperature,
The firing atmosphere firing operation is included.
An atmospheric firing sub-step; and
Including the press firing operation,
A press firing sub-process is included.
The method for producing a light-transmitting substrate with a light-scattering film is characterized in that the maximum temperature of the atmosphere firing temperature in the atmosphere firing sub-step is higher than the maximum temperature of the contact surface temperature of the contact surface of the press member in the press firing sub-step, i.e., the press firing in the firing step is preferably carried out without using a press member and after firing at a temperature higher than the press firing temperature. According to such a method, the glass paste is sufficiently fired before the press firing, and it is possible to prevent the glass paste from melting to the press member during the press firing.

The material constituting the contact surface is preferably amorphous carbon, non-expansion glass, or functional ceramics. Such materials are relatively easy to process smoothly, and are difficult to weld to glass paste, making it possible to stably form a light scattering film with good surface smoothness. By selecting such a pressing member, it is possible to make the surface roughness index Sz, which indicates the surface smoothness of the contact surface, measured using, for example, an atomic force microscope (AFM), 300 nm or less, more preferably 30 nm or less, and it is preferable to have such a contact surface.

In addition, it is preferable that the press firing operation is performed by clamping the glass substrate on which the coating layer is formed between the press member and a clamping member corresponding thereto, and
It is preferable that the clamping member is the same member as the press member. According to such a method, the glass substrate is clamped between press members having the same heat capacity during firing, which prevents warping of the glass substrate due to uneven heating rates on the front and back during firing, ensures uniform contact between the glass substrate surface and the contact surface, and enables the stable formation of a light-scattering film with excellent surface smoothness.

The firing step is preferably carried out while supporting the glass substrate on which the coating layer is formed with a support member. By holding the glass substrate so that the warping of the substrate caused by heating during firing is mitigated by the warping caused by the weight of the glass substrate itself, the glass substrate surface and the contact surface of the press member are in uniform contact with each other, as described above, and a light-scattering film with good surface smoothness can be stably formed.

In the coating step, the glass paste is also coated on the opposite surface to form an opposite surface coating layer, and
In the baking step, it is preferable to bake the opposite surface coating layer together with the coating layer, so that a light scattering structure can be simultaneously formed on the opposite surface.

The light-scattering film preferably contains an amorphous matrix of the first glass material, crystallite particles dispersed in the amorphous matrix and containing crystallites of the first glass material, and glass particles dispersed in the amorphous matrix and containing glass particles of the second glass material, so that the effects of the present invention can be more effectively achieved.

Furthermore, the present invention provides a method for producing an organic EL panel, including the method for producing a light-transmitting substrate with a light-scattering film of the present invention, the method comprising the steps of:
The coating step,
The firing step,
a transparent electrode layer forming step of forming a transparent electrode layer on the transparent electrode layer forming surface;
an organic functional layer forming step of forming an organic functional layer on the light-transmitting electrode layer;
The method for producing an organic EL panel includes a reflective electrode layer formation step of forming a reflective electrode layer on the organic functional layer, and a sealing film formation step of forming a sealing film on the reflective electrode layer, and can produce an organic EL panel that is highly reliable, particularly has a long life, suppresses leakage current during continuous emission, and has high power luminous efficiency.

The light-scattering film-attached transparent substrate manufactured by the manufacturing method of the present invention has little surface irregularity and high surface smoothness, making it possible to form highly reliable and efficient elements. For example, an organic EL panel using this as a raw substrate can maintain a small leakage current, achieving high luminous efficiency with little degradation.

1 is a conceptual diagram of a cross section of an organic EL panel according to an embodiment of the present invention. 1 is a conceptual cross-sectional view showing a state in which a press member 7 is arranged so that the press member contact surface is in contact with the surface of the coating layer in a press firing operation included in the firing step of Example 1. FIG.

The following describes an embodiment of the present invention.

[Transparent substrate 11 with light scattering film]
The light-scattering film-attached translucent substrate 11 according to the present invention is a substrate for layer formation, comprising a glass substrate 1 and a light-scattering film 2 (a light extraction film 2 in the case of a substrate for an organic EL element), with the surface of the light-scattering film 2 opposite the glass substrate 1 serving as a surface for forming a translucent electrode layer. One of its features is that it has an area capable of including, for example, one or more organic EL elements 12 of a desired shape, and is manufactured by a specific manufacturing method, so that the surface for forming the translucent electrode layer has excellent quality as a surface for forming a translucent electrode layer of an element, such as the organic EL element 12.

That is, the surface for forming a translucent electrode layer according to the present invention is a surface of the light-scattering film 2 having a specific and excellent light-scattering performance, and is a smooth surface with few irregularities.
The surface has few foreign objects,
Preferably, the surface roughness index Sz, which indicates the surface smoothness, measured using an atomic force microscope (AFM) is 300 nm or less, more preferably 50 nm or less. Here, as the AFM, Sz can be measured using an AFM such as 5600LS manufactured by Agilent Technologies, which is used in the examples described later.

[Glass substrate 1]
The glass substrate 1 according to the present invention is a main component constituting a light-transmitting substrate 11 with a light-scattering film, and has a film-forming surface and an opposite surface as its two main surfaces, and from the viewpoint of using it as a raw material for manufacturing a light panel, its average thickness is preferably 8 mm or less, more preferably 4 mm or less, and even more preferably 2 mm or less, and from the viewpoint of being easy to handle, it is preferably 0.1 mm or more, more preferably 0.2 mm or more, and even more preferably 0.4 mm or more. The glass substrate 1 has an area that can include one or more light-scattering films 2 of a desired shape.

Such glass substrate 1 may be chemically strengthened to improve resistance to cracking when the glass is thinned and to make a panel that can withstand practical use. In order to make the substrate strong enough, it is preferable that the edges are treated. The substrate may be a single layer or multiple layers without any problems, and a treatment layer or coating film may be formed on any of the surfaces to improve abrasion resistance, smoothness, and resistance to cracking.

[Light scattering film (light extraction film) 2]
The light-scattering film 2 of the present invention is a film that constitutes a light-scattering structure, which has the function of changing the direction of light emission at an interface between adjacent films or layers having different refractive indices, thereby improving the light extraction efficiency and light trapping efficiency, and is preferably formed as a film having an average film thickness of 10 μm or more by heating and baking a coating layer described later, preferably made of a material consisting only of inorganic components.

From the viewpoint of simply, inexpensively, and reliably ensuring the surface smoothness according to the present invention while further increasing the reliability and element efficiency according to the present invention, for example, the luminous efficiency in the case of an organic EL element, it is preferable that such a light-scattering film 2 is a film of inorganic glass having a refractive index of 1 or more and 3 or less, which has a relatively smooth surface, contains fine particulate parts with different refractive indices, contains crystal grain boundaries with a large light-scattering effect, and contains voids where the refractive index is essentially 0. Specifically, for example, the film is made of an inorganic glass having a refractive index of 1 or more and 3 or less, which contains a sea portion of an amorphous matrix of a first glass material, crystallite particles containing crystallites of the first glass material dispersed in this amorphous matrix, and a crystallite having a higher melting point than the first glass material. Preferably, the second glass material has a sea-island structure consisting of islands of glass particles of the second glass material, and more preferably, the second glass material has a refractive index different from that of the first glass material, and a second glass material with a higher melting point than the first glass material is added to the first glass material, which becomes the matrix, to impart a scattering effect, and at the same time, the crystallization temperature of the matrix is raised by the effect of suppressing crystallization of the matrix material at the interface of the high melting point material particles, making it possible to sinter at 500°C or less, thereby maintaining smoothness. One of the characteristics of such a light-scattering film 2 is that it is a film in which a small amount of matrix crystallites are formed.

It is preferable that both the first glass material and the second glass material are _Bi2O3 - _{B2O3 -SiO2 - ZnO} -based glass, which is inexpensive and has excellent transparency. More preferably, for such a glass composition, the total proportion of _SiO2 and _B2O3 in the second glass material is made greater than that of the first glass material, _and the proportion of _Bi2O3 in the second glass material _is made smaller than that of the first glass material, thereby making it possible to easily and inexpensively make the second glass material a material with a higher melting point than the first glass material.

Even more preferably, the composition of the above-mentioned _Bi2O3 - _B2O3 - _{SiO2 -ZnO} -based glass _is 100 wt% as a whole, with _SiO2 being 0-15 wt%, _B2O3 being 0-15 _wt %, _Bi2O3 being 65-90 wt%, ZnO _being 0-20 wt%, _{and Al2O3} , BaO, and ZrO each being in the range of 0-10 wt%, which results in a light extraction film 2 that is cheaper and easier to produce and has better light extraction efficiency and optical properties.

(Method for producing a light-transmitting substrate with a light-scattering film)
The method for manufacturing the light-transmitting substrate 11 with the light-scattering film 2 of the present invention includes, in order, a coating step in which a specific glass paste is applied onto the film-forming surface of the glass substrate 1 to form a coating layer, and a firing step including a specific press firing operation, and one of the features of the firing step is that the glass substrate 1 on which the coating layer has been formed is heated to fire the coating layer.

(Coating process)
The glass paste is, for example, a glass frit, and specifically contains the above-mentioned raw materials of the first glass material and the second glass material.

In the coating process, examples of methods for coating the glass paste on the film-forming surface, and in some cases on the opposite surface, of the glass substrate 1 include screen printing, spin coating, slit coating, and inkjet methods. A screen printing method that is simple and has high controllability over the film thickness is preferred. By coating, a coating layer is formed on the film-forming surface, and an opposite-surface coating layer may also be formed on the opposite surface. In other words, preferably, the glass paste is also applied to the opposite surface to form an opposite-surface coating layer.

(Firing process)
The firing step is a step of firing the coating layer, preferably the opposite side coating layer, by heating the glass substrate 1 on which the coating layer, preferably the opposite side coating layer, is formed, and is characterized by including a specific press firing operation described later, and includes a press firing sub-step including the press firing operation, and preferably includes an atmosphere firing sub-step including an atmosphere firing operation described later before the press firing sub-step, and preferably includes a support member while supporting the glass substrate on which the coating layer, more preferably the opposite side coating layer, is formed, and when the opposite side coating layer is formed, the opposite side coating layer is also fired together with the coating layer. That is, in the coating step, the glass substrate 1 on which the glass paste is applied on both the front and back sides of the glass substrate 1 is further fired in a state where it is sandwiched between the press member 7 and the clamping member from both the front and back sides, so that the glass substrate surface and the contact surface of the press member and the clamping member are uniformly in contact with each other, and a light scattering film with good surface smoothness can be stably formed on both sides of the glass substrate in some cases.

The support member is a member that allows the glass substrate 1 to be fired in a supported state by clamping both corresponding sides, preferably when the opposite side is placed on the glass substrate 1 at a specific position, for example, on the opposite side, in order to perform an atmospheric firing operation on the opposite side coating layer as well. When the opposite side is placed on the support member, it is possible to hold the glass substrate 1 so that the warping of the substrate caused by heating during firing is mitigated by the warping caused by the weight of the glass substrate itself, so that the glass substrate surface and the contact surface of the press member come into uniform contact, and a light scattering film 2 with better surface smoothness can be stably formed.

In such a firing process, it is preferable to set the maximum temperature of the atmosphere firing temperature higher than the maximum temperature of the contact surface temperature of the contact surface of the press member, so that the glass paste is sufficiently fired before press firing, and therefore, it is possible to prevent the glass paste from melting onto the contact surface of the press member 7 during press firing.

(Press firing operation)
The press firing operation according to the present invention is an operation of applying a load to the coating layer in the direction of the glass substrate 1 side through the press member while contacting the press member contact surface of the press member with the surface of the coating layer, and here, the above-mentioned "surface of the coating layer" is the surface that will become the surface for forming the translucent electrode layer according to the present invention, that is, in order to perform firing according to the present invention, during the press firing sub-step, a load is applied from the surface of the glass substrate 1 to which the glass paste is applied with the heated press member 7, and press firing is performed, and the light scattering film 2 on the surface for forming the translucent electrode layer according to the present invention with high surface smoothness can be formed. The load applied to the press member 7, etc. can be appropriately adjusted, for example, by placing an appropriate weight on the press member, etc., or by applying pressure with a cylinder, etc.

This type of press firing operation can also be carried out by clamping the glass substrate 1 on which the coating layer, and preferably the opposite side coating layer, has been formed, from the front and back, between the press member and a clamping member corresponding to the press member.

That is, when an opposite side coating layer is also formed, the press firing operation includes an operation of contacting the clamping member contact surface of the clamping member with the surface of the opposite side coating layer and applying a load to the opposite side coating layer via the clamping member in the direction toward the glass substrate 1. However, unlike the above, the "surface of the opposite side coating layer" is not the surface that will become the surface for forming the translucent electrode layer according to the present invention.

The material constituting the press member contact surface of the press member 7 is preferably amorphous carbon, non-expansion glass, or functional ceramics, more preferably amorphous carbon, from the viewpoint that it is a material that expands or deforms little due to heating during firing, and is relatively easy to make the surface smoothness of the main surface that contacts the glass paste during firing Sz = 1 μm or less, preferably Sz = 0.3 μm or less. Members made of such materials are relatively easy to process smoothly, are difficult to weld to the glass paste, and are preferable from the viewpoint of stably forming a light scattering film 2 with good surface smoothness.

It is preferable that the clamping member is the same as the pressing member, that is, a separate member of the same material and shape that is interchangeable. In this way, during press firing, the glass substrate 1 and the coating layer are sandwiched between the pressing member 7 and the clamping member*, which have the same heat capacity. This makes it possible to suppress warping of the glass substrate 1 due to uneven heating rates on the front and back during press firing, and the contact surfaces of the coating layer surface and the glass substrate surface with the pressing member and clamping member come into uniform contact, allowing the stable formation of a light-scattering film 2 with good surface smoothness. Another advantage is that the operation can be performed without worrying about the front and back of the glass substrate 1 or the positional relationship between the pressing member and the clamping member relative to the glass substrate 1.

On the other hand, as mentioned above, the press member contact surface corresponding to the surface for forming the translucent electrode layer according to the present invention needs to be highly smooth, but in some cases, it may be preferable for the clamping member contact surface to have surface irregularities to provide light scattering properties. From the viewpoint of dealing with such cases, it is preferable that the press member and the clamping member are members that are provided with a contact surface portion that constitutes the contact surface, and that is more preferably detachable, on the same main body portion, and this also has the advantage that the heat capacity can be easily adjusted to an equal value.

(Atmosphere firing operation)
The atmospheric firing operation according to the present invention is an operation in which the surface of the coating layer is not brought into contact with the press member contact surface, and the surface of the coating layer is exposed to a firing atmosphere having an atmospheric firing temperature, which is the temperature of the atmosphere that is the gas surrounding the material to be fired, and is heated by heating. Over the entire period of the firing process including the atmospheric firing sub-process including this atmospheric firing operation, multiple atmospheric firing sub-processes and multiple press firing sub-processes can be included. In this specification, the highest atmospheric temperature over one or more atmospheric firing sub-processes in the entire period is referred to as the maximum atmospheric firing temperature, and the highest press member contact surface temperature over one or more press firing sub-processes in the entire period is referred to as the maximum contact surface temperature. As described above, from the viewpoint of preventing welding, it is preferable that the atmospheric firing sub-process including the atmospheric firing operation that results in the maximum atmospheric firing temperature be performed before the press firing sub-process including the press firing operation that results in the maximum contact surface temperature.

That is, in a firing process that includes, in order, one atmospheric firing sub-process, one press firing sub-process, and, in some cases, a subsequent atmospheric temperature-lowering sub-process, it is preferable to perform the press firing without using the press member 7 and after performing the atmospheric firing operation at a temperature higher than the press firing temperature. According to this method, the glass paste is sufficiently fired before the press firing, and it is possible to prevent the glass paste from melting to the press member 7 during the press firing.

[Organic EL panel 10]
As an example of a product made from a substrate manufactured by the method for manufacturing a light-transmitting substrate with a light-scattering film according to the present invention, an organic EL panel 10 will be briefly described below.

Figure 1 is a conceptual diagram of a cross section of one embodiment of an organic EL panel 10.

The organic EL panel 10 has an organic EL element 12 composed of a translucent electrode layer 3, an organic functional layer 4, and a reflective electrode layer 5, and a sealing film 6 formed on a surface for forming the translucent electrode layer according to the present invention, and the organic EL element 12 includes at least a part of the translucent electrode layer 3.

In such an organic EL panel 10, when a voltage is applied between the translucent electrode layer 3 and the reflective electrode layer 5, the light-emitting layer in the organic functional layer 4 emits light, and the emitted light can be efficiently extracted to the outside by the light extraction film 2.

Here, if there are uneven portions on the surface of the light extraction film 2 of the light extraction substrate 11, the translucent electrode layer 3, the organic functional layer 4, and the reflective electrode layer 5 are formed along the uneven shape. Therefore, when a voltage is applied between the translucent electrode layer 3 and the reflective electrode layer 5, for example, charges are concentrated in the uneven portions, causing leakage current, which reduces the lifespan of the organic EL panel.

According to the present invention, such surface irregularities of the light extraction film are suppressed, the surface is smoothed, and an organic EL panel with long life and high performance is obtained.

[Organic EL element 12]
The organic EL element 12 is a light-emitting device including a translucent electrode layer 3, an organic functional layer 4, and a reflective electrode layer 5, and an organic functional layer 4 including a light-emitting layer containing an organic compound is sandwiched between the translucent electrode layer 3 and the reflective electrode layer 5. The overlapping portion of these layers constitutes the element, and the element emits light when power is supplied to the translucent electrode layer 3 and the reflective electrode layer 5 from the outside.

The organic EL panel 10 of the present invention is formed by forming such an organic EL element 12 and a sealing film 6 in this order on the element formation surface of the light extraction substrate 11 of the present invention.

Any material having high translucency and electrical conductivity can be used as the material for forming the translucent electrode layer 3, but from the viewpoint of reliability and luminous efficiency, a transparent conductive metal oxide is preferred, and it is more preferred that the translucent electrode layer 3 is formed as a film of the material including the translucent electrode layer 3 side power supply portion related to the power supply to the translucent electrode layer 3.

Examples of such transparent conductive metal oxides include ITO and IZO, and the average thickness is preferably 1 μm or less. Thin plates of such materials can be formed by vacuum deposition methods such as CVD and PVD.

The organic functional layer 4 generally has a multilayer structure, for example, from the translucent electrode layer 3 side, such as a hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer, and may also include a connection layer including a charge generation layer, a charge blocking layer, etc.

The material forming the reflective electrode layer 5 is preferably Al or Ag, which has a large reflectance and is effective in improving brightness, and the preferred method for forming the layer is a vacuum deposition method, which can form a high-purity film and easily obtain the original physical properties of the material. It is more preferable that the layer is formed as a translucent electrode layer included in a film of the material, which includes a reflective electrode layer 5 side power supply portion related to the power supply to the reflective electrode layer 5.

(Light scattering structure)
The above-mentioned light scattering structure is a light extraction structure in an organic EL panel, and when light generated in the light-emitting layer inside the organic EL element 12, particularly inside the organic functional layer 4, is radiated from the light-emitting surface to the outside world, the ratio of radiated light to generated light is brought closer to 1, that is, the ratio of extracted light is increased, that is, the "light extraction" efficiency is increased, thereby making the panel high brightness, that is, high luminous efficiency. Specifically, this is a structure for reducing the total reflection that occurs at the interface between the different refractive indexes when light enters a high refractive index medium (e.g., inside the organic EL element 12) into a low refractive index medium (e.g., an ordinary glass substrate) by changing the exit angle of the light.

In addition, such a "light extraction structure" is not only derived from the light extraction film 2 of the present invention, but also preferably utilizes an OC layer including a so-called OCF (out coupling film) arranged on the main surface of the light-scattering-film-attached translucent substrate 11 opposite the light extraction film 2, and more preferably utilizes one or more layers selected from the group consisting of, for example, an adhesive film layer and a resin coating layer.

In order to reduce total reflection by changing the light emission angle, such a light extraction film 2 can have a pyramidal, microlens, moth-eye, or other irregular shape on the side opposite the glass substrate.

[Sealing film 9]
The sealing film 6 is a film formed around and including the entire surface of the reflective electrode layer 5 side of the organic EL element 12 so as to prevent the organic EL element 12 including the organic functional layer 4 and the reflective electrode layer 5 from deteriorating due to exposure of these layers to the atmosphere.

Materials for such a sealing film 6 can be, for example, inorganic substances from the viewpoint of imparting sufficient water vapor barrier properties to the layer, and are preferably silicon oxide and/or silicon nitride, and the average film thickness is preferably 0.5 μm or more and 5 μm or less.

[Method of Manufacturing Organic EL Panel 10]
A method for manufacturing such an organic EL panel 10 includes the method for manufacturing a translucent substrate with a light-scattering film of the present invention, and then includes, in order, a translucent electrode layer formation step of forming a translucent electrode layer on a translucent electrode layer formation surface, an organic functional layer formation step of forming an organic functional layer on the translucent electrode layer, a reflective electrode layer formation step of forming a reflective electrode layer on the organic functional layer, and a sealing film formation step of forming a sealing film on the reflective electrode layer.

The manufacturing method of the organic EL panel 10 can also include a cutting process for cutting one or more organic EL panels 10 from the glass substrate 1, and organic EL panels 10 of the desired shape and quantity can be manufactured from a single glass substrate 1.

The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1
A light extraction substrate 11 serving as Example 1 was produced and evaluated.

First, a glass plate 21 having a refractive index of 1.5, a size of 10 cm x 10 cm and a thickness of 0.7 mm was prepared as the glass substrate 1, a _Bi2O3 - _{B2O3 -SiO2 - ZnO} -based glass frit was prepared as the first glass material, and _{a Bi2O3} - _B2O3 - _{SiO2 -ZnO} -based glass frit was prepared as the second glass material.

Next, the first glass material and the second glass material were mixed in a ratio of 37.5:62.5 by weight to prepare a glass paste.

Next, the prepared glass paste was applied to the entire surface of one main surface of the glass substrate 1 using a screen printer and a screen to an average thickness of 20 μm, creating a coating layer of the glass paste.

Next, the glass substrate 1 on which the glass paste layer was formed was placed in a drying furnace at 120°C for 60 minutes to dry the glass paste.

Figure 2 is a cross-sectional conceptual diagram showing the dried glass paste formed on the film-forming surface of the glass substrate 1 in the press firing operation in the press firing sub-process included in the firing process of Example 1, in which the workpiece is placed in a firing furnace in which the firing process is carried out, placed on the workpiece holder, and then positioned so that the press member contact surface of the press member 7 is in contact with the surface of the coating layer from the room temperature state before the start of heating the press member.

In this way, the glass paste that was dried in a drying furnace before being placed in the firing furnace was fired in a firing process that only included a press firing operation, with the contact surface temperature of the press member contact surface reaching a maximum temperature of 420°C and maintained at this maximum temperature for 60 minutes, with firing also included during the temperature increase and decrease processes before and after this, to produce a light extraction substrate 11 on which a light extraction film 2 was formed.

The press member contact surface of the press member 7 used in this Example 1 is made of amorphous carbon, and its surface roughness index Sz, which indicates surface smoothness, was 53 nm when measured using an atomic force microscope (AFM) 5600LS manufactured by Agilent Technology.

The surface smoothness of the light extraction film 2 of Example 1 thus produced was evaluated using an AFM.

Table 1 shows Sz, which indicates the surface smoothness of the light extraction film 2 according to Example 1, Examples 2 and 3 described below, and Comparative Example 1.

(Comparative Example 1)
As Comparative Example 1, a light extraction substrate having a light extraction film of Comparative Example 1 formed thereon was produced and evaluated in the same manner as in Example 1, except that a firing process including only an atmospheric firing operation was carried out instead of the firing process including only a press firing operation in Example 1.

The atmosphere in this atmospheric firing operation is air, and the maximum contact surface temperature of the press member contact surface in Example 1 is the maximum atmospheric firing temperature in Comparative Example 1.

Example 2
In Example 2, instead of the firing process including only the press firing operation in Example 1, a firing process including both sub-processes, that is, an atmospheric firing sub-process and then a press firing sub-process, was carried out. Except for this, firing was carried out in the same manner as in Example 1, and a light extraction substrate 11 having a light extraction film 2 of Example 2 formed thereon was produced and evaluated.

Here, in the atmospheric firing operation in the atmospheric firing sub-process in the atmospheric firing furnace, the atmosphere was air, the maximum atmospheric firing temperature was 450°C, and the maintenance time at this temperature was 60 minutes. The press firing sub-process was carried out in the same manner as the press firing sub-process in Example 1.

Example 3
As Example 3, like Example 1, the firing process only included a press firing operation. However, except that the press firing operation was performed while the substrate was clamped from the front and back with the same clamping members as the press member 7, press firing was performed in the same manner as in Example 1, and a light extraction substrate 11 having a light extraction film 2 of Example 3 formed thereon was produced and evaluated.

(summary)
The light extraction film 2 of Example 1 has a lower Sz, which indicates surface smoothness, and a higher surface smoothness, due to the effects of the present invention, compared to the light extraction film 2 of Comparative Example 1.

This is thought to be due to the fact that foreign matter on the glass paste and glass particles of the second glass material are pushed into the glass paste during firing by applying a load during firing using the press member 7, which has sufficient surface smoothness.

In addition, the light extraction film 2 of Example 2 is free of welding of the press members and has a slightly lower Sz, which indicates surface smoothness, and has high surface smoothness, due to the effects of the present invention, compared to the light extraction film 2 of Example 1.

This is thought to be because the glass paste was sufficiently fired before the press firing, preventing the glass paste from melting onto the press member 7 during the press firing.

In addition, the light extraction film 2 of Example 3 has a lower Sz, which indicates surface smoothness, and a higher surface smoothness, due to the effect of the present invention, compared to the light extraction film 2 of Example 1.

This is thought to be because the glass substrate 1 was pressed and fired while being sandwiched between the same material as the press member 7 on both sides, which prevented the glass substrate 1 from warping due to uneven heating rates on the front and back during firing, and ensured uniform contact between the glass substrate surface and the contact surface of the press member.

Reference Signs List 1 Glass substrate 2 Light extraction film 3 Light-transmitting conductive layer 4 Organic functional layer 5 Reflective conductive layer 6 Sealing film 7 Press member 10 Organic EL panel 11 Light extraction substrate 12 Organic EL element

Claims (8)

A method for producing a light-scattering film-attached translucent substrate for forming a light-scattering electrode layer, comprising: a glass substrate having a film-forming surface and an opposite surface as two main surfaces; and a light-scattering film, the surface of the light-scattering film opposite to the glass substrate being a surface for forming a light-scattering electrode layer,
the light-scattering film includes a first glass material and a second glass material having a higher melting point than the first glass material;
a coating step of coating a glass paste containing the raw materials of the first glass material and the second glass material on the film-forming surface to form a coating layer; and a firing step of firing the coating layer.
The firing step includes a press firing operation in which a press member contact surface of a press member is brought into contact with a surface of the coating layer, which is to be a surface for forming the translucent electrode layer, and a load is applied to the coating layer in a direction toward the glass substrate via the press member , and further includes
The press member includes a contact surface portion that is detachable from the main body and that constitutes the press member contact surface, and further includes
A method for producing a light-transmitting substrate with a light-scattering film, wherein the material of the contact surface is amorphous carbon, non-expansion glass, or functional ceramics . A method for producing a light-transmitting substrate with a light-scattering film according to claim 1, comprising the steps of:
The press firing operation is carried out by clamping the glass substrate having the coating layer formed thereon between the press member and a clamping member corresponding thereto, and
The method for producing a light-transmitting substrate with a light-scattering film is characterized in that the clamping member is provided with a main body portion and a detachable contact surface portion that constitutes a contact surface. The firing step is performed in the order of:
The press member contact surface is not brought into contact with the surface of the coating layer, and
Exposing the surface of the coating layer to a baking atmosphere at a baking temperature,
The firing atmosphere firing operation is included.
An atmospheric firing sub-step; and
Including the press firing operation,
A press firing sub-process is included.
3. The method for manufacturing a light-transmitting substrate with a light-scattering film according to claim 1 or 2 , wherein a maximum temperature of the atmospheric firing temperature in the atmospheric firing sub-step is higher than a maximum contact surface temperature of the contact surface of the press member in the press firing sub-step. A method for producing a light-transmitting substrate with a light-scattering film according to claim 2 or 3 , comprising the steps of :
The method for producing a light-transmitting substrate with a light-scattering film, wherein the clamping member is the same member as the pressing member. A method for producing a light-transmitting substrate with a light-scattering film according to any one of claims 1 to 4, comprising the steps of:
The method for producing a light-transmitting substrate with a light-scattering film , wherein the firing step is performed while the glass substrate on which the coating layer is formed is supported by a supporting member. A method for producing a light-transmitting substrate with a light-scattering film according to any one of claims 1 to 5, comprising the steps of:
In the coating step, the glass paste is also coated on the opposite surface to form an opposite surface coating layer, and
A method for producing a light-transmitting substrate with a light-scattering film, wherein in the firing step, the opposite surface coating layer is also fired together with the coating layer. The method for producing a light-transmitting substrate with a light-scattering film according to any one of claims 1 to 6, wherein the light-scattering film comprises an amorphous matrix of the first glass material, crystallite particles dispersed in the amorphous matrix and containing crystallites of the first glass material, and glass particles dispersed in the amorphous matrix and containing glass particles of the second glass material. A method for producing an organic EL panel, comprising the method for producing a light-scattering film-attached light-transmitting substrate according to any one of claims 1 to 7, the method comprising the steps of:
The coating step,
The firing step,
a transparent electrode layer forming step of forming a transparent electrode layer on the transparent electrode layer forming surface;
an organic functional layer forming step of forming an organic functional layer on the light-transmitting electrode layer;
a reflective electrode layer forming step of forming a reflective electrode layer on the organic functional layer; and a sealing film forming step of forming a sealing film on the reflective electrode layer.

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