JP2006147344A - Transparent conducting plate and method for manufacturing the same, and photoelectric conversion device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new structure for a transparent conducting plate, which reduces an electric resistance of the transparent conducting plate and can improve its optical transparency; and to provide a method for manufacturing the transparent conducting plate and a photoelectric conversion device equipped with the transparent conducting plate. <P>SOLUTION: A transparent conducting plate 10 includes an optically transparent substrate 14, a light gathering curved surface 13 which is placed on a first main surface of the optically transparent substrate 14, and a collector 11 and an optically transparent conducting film 15 which are placed on a second main surface of the optically transparent substrate 14, where the second main surface has a first area in which the collector 11 is formed and a second area in which the collector 11 is not formed, and the light gathering curved surface 13 is formed so as to guide at least a part of light incident from the first main surface along a direction orthogonal to the first main surface to the second area. The transparent conducting plate can be manufactured by using for example a photosensitive resist. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a transparent conductive plate and a manufacturing method thereof, and further relates to a photoelectric conversion element provided with the transparent conductive plate.

Conventionally, in a photoelectric conversion element such as a solar cell, a transparent conductive plate having a light-transmitting conductive film such as an ITO film or a SnO ₂ film is disposed on the light incident surface of the element. Although this light-transmitting conductive film is used as an electrode on the incident light side, the light-transmitting conductive film inherently has a higher electrical resistivity than a general metal electrode, so the surface of the transparent conductive plate This is a factor that keeps resistance high.

In order to lower the electrical resistivity of the light-transmitting conductive film, the conductive film may be provided thicker, but the greater the thickness, the lower the transparency. On the other hand, when the metal grid is provided in contact with the light-transmitting conductive film, the electrical resistivity of the conductive film can be lowered by the current collecting action, but the metal grid obstructs the waveguide of incident light, and the transparent conductive film There is a problem of deteriorating the light transmittance of the plate.

Here, there is a technique of providing a metal grid having an acute edge shape for the purpose of preventing light shielding by such a metal grid (see Patent Document 1).
JP-A-8-287969

However, in the transparent conductive plate of Patent Document 1, since the surface of the glass plate needs to be processed with high precision in accordance with the edge shape of the metal grid, the manufacturing yield of the transparent conductive plate is low, and the manufacturing process thereof There is a problem that the number is large. In addition, the transparent conductive plate cannot improve its electrical resistance and light transmittance to a practically sufficient level, and there is room for further lowering the electrical resistance and further improving the light transmittance.

Therefore, an object of the present invention is to provide a novel configuration capable of improving the light transmittance while reducing the electrical resistance of a transparent conductive plate. Another object of the present invention is to provide a novel method for producing a transparent conductive plate and a photoelectric conversion element provided with the transparent conductive plate.

The conventional technique for controlling the waveguide path of incident light by the edge shape of the metal grid has limitations as described above. The inventor has established a new technique capable of precisely controlling the waveguide of incident light, and has completed the present invention.

The transparent conductive plate of the present invention is provided on a light transmissive substrate, a condensing curved surface provided on the first main surface of the light transmissive substrate, and a second main surface of the light transmissive substrate. A current collector and a light-transmitting conductive film, and the second main surface has a first region where the current collector is formed and a second region where the current collector is not formed, The condensing curved surface is formed so as to guide at least part of light incident on the first region from the first main surface side along the direction perpendicular to the first main surface to the second region. It is characterized by being.

In another aspect of the present invention, as a method suitable for manufacturing the transparent conductive plate, light incident on the first region from the first main surface side along a direction perpendicular to the first main surface is provided. A method of manufacturing a transparent conductive plate is provided, wherein the condensing curved surface and the current collector are arranged so that at least a part of the condensing surface is guided to the second region.

According to the present invention, since the current collector provided on the second main surface of the light transmissive substrate can be used as a current collecting element of the light transmissive conductive film on the second main surface, the light transmissive conductive material can be used. It is possible to reduce the electrical resistance while increasing the light transmittance of the conductive film portion by reducing the thickness of the film. Furthermore, since the incident light on the transparent conductive plate can be collected so as to avoid the current collector, the transmission of the incident light can be prevented from being obstructed by the current collector. This excellent light transmittance and low resistance are extremely useful as an incident photoelectrode of a photoelectric conversion element such as a dye-sensitized solar cell.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The transparent conductive plate 10 shown in the sectional view of FIG. 1 has a light transmissive substrate 14. A condensing lens group including two or more condensing lenses 19 having a condensing curved surface 13 in contact with the first main surface of the light transmissive substrate 14 is provided. On the second main surface facing the first main surface of the light transmissive substrate 14, a current collector 11 having an opening 12 is provided in contact with the second main surface. A light transmissive conductive film 15 is provided so as to cover the current collector 11. Hereinafter, the second main surface portion where the current collector 11 is formed is referred to as a first region, and the second main surface portion where the current collector 11 is not formed is referred to as a second region.

The material for the light-transmitting substrate 14 is preferably the one that can increase the light-transmitting property of the substrate.
For example, a glass sheet or a resin sheet such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene sulfide, or polyimide can be used.

As the material of the current collector 11, a material having low electrical resistivity and high corrosion resistance is preferable.
For example, copper, nickel, silver, gold, platinum, tantalum, titanium, ruthenium, carbon, or the like can be used. The current collector 11 is more preferably formed from a material having a lower electrical resistivity than the material constituting the light transmissive conductive film 15. The detailed shape of the current collector 11 will be described later.

As the material of the light transmissive conductive film 15, a material having high light transmittance and low electrical resistivity is preferable. For example, tin oxide, zinc oxide, ITO (tin doped indium oxide), FTO (
Fluorine-doped tin oxide) can be used.

In the above embodiment, the current collector 11 is provided between the light transmissive conductive film 15 and the second main surface. However, the current collector 11 and the light transmissive conductive film 15 are mutually connected. As long as it arrange | positions so that it may contact | connect, it may replace with this and may be set as the structure where the transparent conductive film 15 was provided between the electrical power collector 11 and the 2nd main surface. In the latter structure, it is preferable to cover the current collector with a known insulating film or the like in order to avoid exposure of the current collector.

The shape of the condensing lens 19 is first from the first main surface side along the direction perpendicular to the first main surface.
There is no particular limitation as long as the light condensing property of guiding at least part of the light incident on the region to the second region can be exhibited. For example, the condensing lens may have a microlens shape shown in FIG. 2 or a cylindrical shape shown in FIG. The curvature and the like of the converging curved surface 13 may be appropriately selected according to the shape of the current collector 11 and the size of the transparent conductive plate 10.

When the condensing lens is a microlens shape, the shape when viewed in plan is not particularly limited,
Circular, oval, rectangular, triangular, hexagonal, etc., but in order to place the condensing lens close to each other without gaps, a condensing lens made of a rectangle, triangle, hexagon, etc., or a combination thereof A group is preferred.

The material of the condensing lens is not particularly limited, and any of inorganic materials and organic materials can be used, but those having excellent weather resistance are preferable.

In addition, as long as the said condensing property is not inhibited, you may provide the protective layer which has a light transmittance on the surface of this condensing lens. Thereby, the intensity | strength of a transparent conductive plate can be improved, the surface of a condensing curved surface can be protected, or the said surface can be planarized.

Here, the arrangement and shape of the current collector 11 will be described in detail. The arrangement and shape of the current collector 11 are closely related to the arrangement and shape of the condenser lens 19. In other words, the current collector 11 and the condensing lens 19 are configured such that at least part of light incident on the first region from the first main surface side along the direction perpendicular to the first main surface, preferably a majority of the light. The relative arrangement and shape of the two are so defined as to lead them to the second region.

First, the arrangement of the current collector 11 will be described. In the present embodiment, the opening portion 12 of the current collector 11 has an opening width that is wider than the width of incident light that is collected on the second main surface of the light transmissive substrate 14. More specifically, as shown in FIG. 9, the opening end face (corresponding to the end face of the current collector 11) 17 of the opening and the light condensing light that is closest to the opening end face and collects light toward the opening. The current collector 11 and the condensing curved surface 13 are relatively disposed so that the shortest distance (w) between the optical axis of the curved surface satisfies the following formula (1).
(F−d) h / F ≦ w <h (1)
However, h in the formula is the optical axis of the condensing lens closest to the opening end surface and the condensing curved surface edge 18 of the condensing curved surface 13 of the condensing lens, and the condensing curved surface edge 18 closest to the opening end surface. , D is the thickness of the light transmissive substrate, and F is the focal length of the converging curved surface in the medium equal to the refractive index of the light transmissive substrate.

As long as the above-described formula (1) is satisfied, the first main surface portion corresponding to the second region may be provided with two or more condensing lenses 19 as in the structure shown in FIG. 9 or FIG. However, from the side of increasing the contact area between the current collector 11 and the light-transmitting conductive film 15 and reducing the resistance of the transparent conductive plate, a condensing curved surface of one condensing curved surface as shown in FIG. It is preferable that a current collector is disposed on each of the second main surface portions corresponding to the inside vicinity of the edge 18. Further, since the resistance of the transparent conductive plate can be reduced as the contact area is increased, the shortest distance (w) is most preferably set to an aspect equal to (F−d) h / F.

Furthermore, it is preferable that the condensing curved surface 13 is arranged on the first main surface portion corresponding to the first region from the side surface for preventing the transmission of incident light from being disturbed by the current collector. For example, FIG.
In the case where the two condensing lenses are arranged without being close to each other as shown by the following, the second main surface portion corresponding to the condensing curved surface edge 18 of each condensing curved surface while satisfying the above formula (1). It is preferable that the condensing lens and the current collector are relatively arranged so as not to protrude.

The “distance between the condensing curved surface edge and the optical axis” refers to the radius of the microlens when the condensing lens is a microlens shape having no distortion as shown in FIG. For example, in the case of a cylindrical curved surface having no distortion as shown in FIG. 6, the half value of the width in the short direction of the cylindrical shape corresponds to this.

9 and the like show an aspect in which the thickness and width of each current collector are equal, but the thickness and width may be different depending on the shape and size of the condenser lens. .

Subsequently, the shape of the current collector 11 will be described. FIG. 3 is a front view from the second main surface side of the transparent conductive plate in which the condensing lens 19 has a microlens shape, and the current collector 11 and the condensing curved surface 1.
FIG. FIG. 4 is a diagram illustrating another example of the relative arrangement. FIG. 5 is a diagram showing another example of the relative arrangement. FIG. 7 is a front view from the second main surface side of the transparent conductive plate in which the condensing curved surface 13 of the condensing lens 19 is cylindrical, and shows the relative arrangement of the current collector 11 and the condensing curved surface 13. FIG. In each figure, the condensing curved surface 13 provided on the 1st main surface is shown with the broken line.

As for the shape of the current collector 11, the condensing shape on the second main surface by the condensing curved surface 13 is the inner shape, and the shape of the condensing curved surface edge of the condensing curved surface 13 is the outer shape. When the condensing lens 19 is a microlens shape having a perfect circle front shape without distortion, the current collector 11 has a perfect circle shape as shown in FIG. It becomes a shape. On the other hand, when the condensing curved surface of the condensing lens 19 is a cylindrical shape without distortion, the current collector 11 has both its inner shape and outer shape as shown in FIG. It becomes a parallel straight line shape that coincides with the longitudinal direction of the cylindrical shape. In any case, the light condensing shape and the opening 1 of the current collector 11 are used.
It is preferred that the shape of 2 essentially matches.

By the way, from the side of increasing the contact area between the current collector 11 and the light transmissive conductive film 15 and reducing the resistance of the transparent conductive plate, increasing the arrangement area of the current collector on the second main surface as much as possible. That is, it is preferable to increase the arrangement density of the condenser lenses 19 as much as possible. Therefore, when each condensing lens is made into a perfect circle, for example, it is preferable that the condensing lens group has the highest density filling arrangement as shown in FIG. Furthermore, as described above, in order to arrange the condensing lenses close to each other without a gap, it is more preferable to use a condensing lens group made of a rectangle, a triangle, a hexagon, or the like, or a combination thereof. For example, as shown in FIG. 5, the regular hexagonal condensing curved surface 13 is filled with the highest density.

In addition, when the adjacent condensing lenses are arranged close to each other in this way, the current collectors provided on the second main surface portion corresponding to the vicinity of the condensing curved surface edge of each condensing curved surface are two independent For example, as shown in FIG. 1, the entire structure of the current collector has a grid shape.

In the case of the transparent conductive plate shown in this embodiment, the incident light to the transparent conductive plate can be condensed by the condensing curved surface, and the optical path can be guided so as to avoid the current collector. It can be prevented from being disturbed by the current collector. Furthermore, since the contact area between the current collector and the light-transmitting conductive film can be greatly increased without obstructing the waveguide of incident light, the light-transmitting conductive film portion is thinned so that the light transmitting property of the conductive film portion is reduced. The electrical resistance can be lowered while increasing the resistance. Therefore, the light transmittance of the transparent conductive plate can be improved and the resistance can be reduced. This excellent light transmittance and low resistance are extremely useful as an incident photoelectrode of a photoelectric conversion element such as a solar cell or an optical sensor. In addition, especially in a dye-sensitized solar cell, since the request | requirement with respect to the low resistance of a transparent conductive plate is strong, the usefulness of this transparent conductive plate is high.

In addition, when the light-transmitting conductive film is provided thick, the transparency is lowered as described above, and the conductive film may be cracked when the substrate is bent. Although it is not easy to make the transparent conductive plate shown in the present embodiment, since the light transmissive conductive film can be thinned, a flexible transparent conductive plate can be formed by configuring the light transmissive substrate with a resin sheet. Can be provided.

Below, the preferable one form of the manufacturing method of the said transparent conductive plate is demonstrated, referring drawings.

First, as shown in FIG. 10, a light-transmitting substrate 10, a condensing lens 19 having a condensing curved surface 13 provided on the first main surface of the light-transmitting substrate, and the light-transmitting substrate A transparent conductive plate precursor including a negative photosensitive resist film 21 provided on the second main surface is prepared.

The condensing lens 19 can be formed on the light-transmitting substrate by, for example, a transfer method using a mold or a method using a photosensitive material.
A light-transmitting substrate on which 9 is formed may be used.

The photosensitive resist film 21 may be formed by application of a liquid material or may be formed by attaching a film-like material, but using a light-transmitting substrate on which the resist film 21 has been formed in advance. Also good. As a material for the resist film 21, it is preferable to select a resist of a material system in which the condensing lens 19 is not easily deteriorated in a resist development and peeling process, which are subsequent processes. In addition, the thickness of the resist film 21 is preferably set to be thicker than the designed thickness of the current collector formed in a subsequent process.

In addition, since the handling as a self-supporting board | substrate becomes difficult when using a thin light-transmitting board | substrate, you may produce this transparent conductive plate precursor as follows. First, a condenser lens is formed on the first main surface of a light-transmitting substrate that is thinly formed on a metal or resin support substrate. Next, a light-transmitting protective film is further formed on the condensing lens to sufficiently increase the strength. Subsequently, the support substrate is peeled off by etching or peeling. Finally, a resist film 21 is formed on the second main surface of the light transmissive substrate.

The transparent conductive plate precursor is processed as follows to produce a transparent conductive plate. First, light for exposure is applied to the resist film 21 from the converging curved surface side, preferably from a direction perpendicular to the first main surface. Since this exposure light is condensed by each condensing curved surface 13 and reaches the second main surface, the resist film 21 is partially exposed to become a resist 22 as shown in FIG. As this exposure source, it is preferable to use an apparatus capable of irradiating parallel light, such as a projection exposure machine or a proximity exposure machine.

Thereafter, the resist film 21 is developed to process a predetermined resist pattern. Since a negative resist film is used, as shown in FIG. 12, an island-shaped resist 23 in which only the exposed resist 22 remains is formed.

Next, a conductive layer 16 is formed as shown in FIG. 13 so as to cover the island-shaped resist 23, that is, in contact with the island-shaped resist surface and the second main surface exposed by removing the resist. . The conductive layer 16 may be formed by a known method such as an evaporation method, a sputtering method, a chemical vapor deposition method (CVD method), a coating method, or a sol-gel method. The conductive layer 16 is made of copper,
The material is nickel, silver, gold, platinum, tantalum, titanium, ruthenium, carbon or the like. Note that in order to reduce the electrical resistivity of the light-transmitting conductive film formed in the subsequent step, it is preferable to form the conductive layer 16 as thick as possible, but it is easy to remove a part of the conductive layer in the subsequent step. For this reason, it is preferable that the thickness of the island-shaped resist 23 be smaller than that of the island-shaped resist 23.

Subsequently, the conductive layer formed on the surface of the island-shaped resist 23 is removed together with the resist 23 to form a current collector 11 having an opening 12 as shown in FIG.

Finally, as shown in FIG. 15, the current collector 11 is covered so as to cover the surface of the current collector 11 and the second main surface exposed by removing the resist together with a part of the conductive layer. A light transmissive conductive film 15 is formed on the substrate. Thereby, the transparent conductive plate 10 is completed. The light transmissive conductive film 15 may be formed by a known method such as a vapor deposition method, a sputtering method, a chemical vapor deposition method (CVD method), a coating method, or a sol-gel method.

In addition to the above-described embodiment including the step of patterning a resist film by exposure through a condensing curved surface, for example, a condensing lens and a current collector are prepared in advance and incident on the condensing curved surface. The light path of the light to be transmitted is in a relative arrangement so as to avoid the current collector, on the first main surface and the second main surface of the light transmissive substrate along the direction perpendicular to the first main surface from the first main surface side. It is good also as an aspect which arrange | positions a condensing curved surface and a collector so that at least one part of the light which injects into the said 1st area | region may be guide | induced to the said 2nd area | region.

However, in the above embodiment, the current collector can be formed so that the optical path of incident light collected by the condensing curved surface reliably avoids the current collector, that is, the condensing curved surface and the current collector. This is particularly preferable because they can be reliably and simply disposed relative to each other without causing any positional deviation.

The present invention can also be applied to a transparent conductive plate with reduced electrical resistance and improved light transmission, and a photoelectric conversion element provided with the transparent conductive plate.

It is sectional drawing which shows an example of the transparent conductive plate of this invention. It is a perspective view which shows an example of the transparent conductive plate of this invention. It is a front view from the 2nd main surface side of the transparent conductive plate shown in FIG. 2, Comprising: It is a figure which shows relative arrangement | positioning with a collector and a condensing curved surface. It is a front view from the 2nd main surface side of the transparent conductive plate of this invention, Comprising: It is a figure which shows another example of relative arrangement | positioning with a collector and a condensing curved surface. It is a front view from the 2nd main surface side of the transparent conductive plate of this invention, Comprising: It is a figure which shows another example of relative arrangement | positioning with a collector and a condensing curved surface. It is a perspective view which shows another example of the transparent conductive plate of this invention. It is a front view from the 2nd main surface side of the transparent conductive plate shown in FIG. 6, Comprising: It is a figure which shows relative arrangement | positioning with an electrical power collector and a condensing curved surface. It is sectional drawing of the transparent conductive plate of this invention, Comprising: It is a figure which shows another example of relative arrangement | positioning with a collector and a condensing curved surface. It is sectional drawing of the transparent conductive plate of this invention, Comprising: It is a figure for demonstrating relative arrangement | positioning with a collector and a condensing curved surface. It is a figure which shows a part of manufacturing process of the transparent conductive plate of this invention, and is a figure which shows the structure of a transparent conductive plate precursor. It is a figure which shows a part of manufacturing process of the transparent conductive plate of this invention, and is a figure for demonstrating the process of exposing a part of resist film. It is a figure which shows a part of manufacturing process of the transparent conductive plate of this invention, and is a figure for demonstrating the process of removing resist films other than the part exposed and forming an island-like resist. It is a figure which shows a part of manufacturing process of the transparent conductive plate of this invention, and is a figure for demonstrating the process of forming a conductive layer on the 2nd main surface of a transparent substrate so that an island-like resist may be covered. It is. It is a figure which shows a part of manufacturing process of the transparent conductive plate of this invention, and is a figure for demonstrating the process of forming the electrical power collector which has an opening part. It is a figure which shows a part of manufacturing process of the transparent conductive plate of this invention, and demonstrates the process of forming a light-transmitting electrically conductive film on the 2nd main surface of a light-transmitting board | substrate so that a collector may be covered. FIG. It is sectional drawing of the transparent conductive plate of this invention, Comprising: It is a figure which shows another example of relative arrangement | positioning with a collector and a condensing curved surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transparent conductive plate 11 Current collector 12 Opening part 13 Condensing curved surface 14 Light transmissive substrate 15 Light transmissive conductive film 16 Conductive layer 17 Opening end surface 18 Condensing curved surface edge 19 Condensing lens 21 Resist film 22 Photosensitive resist 23 Island Resist

Claims (8)

A light transmissive substrate;
A condensing curved surface provided on the first main surface of the light-transmitting substrate;
A current collector and a light transmissive conductive film provided on the second main surface of the light transmissive substrate;
Including
The second main surface has a first region in which the current collector is formed and a second region in which the current collector is not formed,
The condensing curved surface is formed so as to guide at least part of light incident on the first region from the first main surface side along the direction perpendicular to the first main surface to the second region. A transparent conductive plate characterized by comprising: The transparent conductive plate according to claim 1, wherein a shortest distance (w) between an end face of the current collector and an optical axis of the condensing curved surface satisfies the following expression (1).
(F−d) h / F ≦ w <h (1)
Where h is the distance between the optical axis of the condensing curved surface and the condensing curved surface edge of the condensing curved surface that is closest to the opening end surface, and d is the light The thickness of the transmissive substrate, and F is the focal length of the condensing curved surface in the medium equal to the refractive index of the light transmissive substrate.   The transparent conductive plate according to claim 1, wherein the condensing curved surface is a microlens.   The transparent conductive plate according to claim 1, wherein the condensing curved surface is a cylindrical condensing curved surface. The current collector is provided between the light transmissive conductive film and the second main surface, and the current collector and the light transmissive conductive film are in contact with each other;
The light transmissive conductive film is provided between the current collector and the second main surface, and the current collector and the light transmissive conductive film are in contact with each other. Transparent conductive plate. A light-transmitting substrate; a light collecting curved surface provided on the first main surface of the light-transmitting substrate; and a current collector and light-transmitting conductive material provided on the second main surface of the light-transmitting substrate. A transparent conductive plate manufacturing method, wherein the second main surface includes a first region in which the current collector is formed and a second region in which the current collector is not formed. ,
The condensing curved surface and the current collector so that at least a part of light incident on the first region from the first main surface side along the direction perpendicular to the first main surface is guided to the second region. A method for producing a transparent conductive plate, comprising: arranging a body. A transparent conductive material comprising: a light transmissive substrate; a condensing curved surface provided on the first main surface of the light transmissive substrate; and a photosensitive resist film provided on the second main surface of the light transmissive substrate. Exposing a part of the photosensitive resist film through the condensing curved surface of the plate precursor;
Removing the photosensitive resist film other than the exposed part, and processing the photosensitive resist film into a predetermined resist pattern;
Forming a conductive layer on the second main surface so as to cover the predetermined resist pattern;
Removing the conductive layer on the predetermined resist pattern together with the predetermined resist pattern;
The method for producing a transparent conductive plate according to claim 6, further comprising: forming the current collector. The photoelectric conversion element provided with the transparent conductive plate of any one of Claims 1-5.