JP2005347490A - Substrate with transparent conductive oxide film, its manufacturing method and photoelectric transfer element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate with a transparent conductive oxide film which is at a low resistance, high transparent, and has a good light scattering performance in all wavelength areas of a sunlight, and has an excellent mass production, and in particular, in which even when a transport type CVD device is used, variations of a C illuminant Hayes rate are sufficiently small; and to provide its manufacturing method and a photoelectric transfer element using the substrate. <P>SOLUTION: In the substrate with the transparent conductive oxide film, the transparent conductive oxide film which is constituted of a plurality of crests and a plurality of flat parts, and has a plurality of micro-projections continuously on the surface of the crests and flat parts is provided on the substrate. In the substrate with the transparent conductive oxide film, further, a spectral Hayes rate is 10 to 95% over all the wavelength areas of 400 to 800 nm, and a difference between a maximum value and a minimum value (the maximum value - the minimum value) of the spectral Hayes rate is not more than 50%. When the C illuminant Hayes rate is measured by a Hayes meter about the entire surface of the substrate, the C illuminant Hayes rate is 30 to 90%, and a difference between a maximum value and a minimum value (the maximum value - the minimum value) of the C illuminant Hayes rate is not more than 20%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate with a transparent conductive oxide film, a method for producing the same, and a photoelectric conversion element (particularly a solar cell) using the substrate with a film.

Thin film solar cells that are photoelectric conversion elements include amorphous silicon (a-Si) and polycrystalline silicon depending on the type of power generation layer. These thin film silicon solar cells include an incident light side. A transparent conductive oxide film is used as an electrode. This transparent conductive oxide film is required to have low resistance and high transparency and high light scattering performance in order to increase photoelectric conversion efficiency.
Patent Document 1 states that “a fluorine-doped tin oxide containing 0.01 to 4 mol% of fluorine with respect to tin oxide and having an electric conductor density of 5 × 10 ¹⁹ to 4 × 10 ²⁰ cm ⁻³ on a translucent substrate. A solar cell in which a first transparent electrode, an a-Si photoelectric conversion layer, and a second conductive film are sequentially stacked by exposing the film to a non-oxidizing atmosphere, and has a low resistance and a high transmittance. A high-quality fluorine-doped transparent conductive film having high durability against hydrogen active species such as hydrogen plasma and hydrogen ions has been proposed.
Patent Document 2 states that “a first peak having a concavo-convex structure surface having a dominant peak / peak value of 100 nm or more and a thickness between about 250 nm and about 1000 nm and transmitting light in a specific wavelength range”. And a semiconductor substrate covering the concavo-convex structure surface of the first electrical contact. ”, A light detector having a concavo-convex structure surface capable of increasing the absorption rate of incident light is described. Photoelectric contact has been proposed.

On the other hand, thin-film crystalline silicon solar cells using thin-film polycrystalline silicon and thin-film microcrystalline silicon, which have been actively studied in recent years, are known to have higher cell sensitivity in the long wavelength region than amorphous silicon solar cells. The transparent conductive film is required to have high transparency and light scattering properties in a longer wavelength range.
In order to increase light scattering at a long wavelength, it is known that it is effective to make the surface uneven structure of the transparent conductive film larger. However, if the film thickness is increased, the crystal grain size increases and the surface irregularities can be increased. However, a transparent conductive film such as a fluorine-doped SnO ₂ film absorbs light in a long wavelength region due to free electrons. If the film is made thick, light absorption increases and the transmittance decreases. As a result, even if light scattering on the long wavelength side increases by increasing the surface irregularities, the light absorption at the long wavelength also increases, so the photoelectric conversion efficiency of the solar cell as a whole does not increase, so the spectral haze ratio is high. It was difficult to increase the efficiency of photoelectric conversion using a transparent conductive film.

In addition to the above, a technique for increasing the light scattering effect by controlling the surface unevenness of the transparent conductive film in contact with the photoelectric conversion layer is known (see, for example, Patent Documents 3 to 7).
Among them, Patent Documents 3 and 4 disclose transparent electrode films represented by indium / tin oxide and SnO ₂ formed by a conventional electron beam vapor deposition method, vacuum deposition method, sputtering method, CVD method, spray method. Is described that the difference in height of the surface irregularities is about 20 to 100 nm, the interval between the convex portions is about 50 to 200 nm, and the light scattering effect at the interface with the photoelectric conversion layer is insufficient. On the other hand, the surface of the transparent electrode film is chemically etched to form a concavo-convex surface having a height difference of about 100 to 500 nm and an interval between the convex parts of about 200 to 1000 nm, thereby scattering light at the interface. It is described that the effect can be increased and the photoelectric conversion rate can be increased. However, in this method, after forming the transparent electrode film, it is necessary to perform a chemical etching process, and after sufficiently washing and drying the substrate to remove the etching solution, it is necessary to form a photoelectric conversion layer. There were problems such as complicated processes and low mass productivity.

  Patent Document 7 discloses that “a transparent electrode sequentially laminated on a substrate, a photoelectric conversion unit including a one-conductivity-type layer, a crystalline silicon-based photoelectric conversion layer, and a reverse-conductivity type layer, a light-reflective metal electrode, In the silicon-based thin film photoelectric conversion device, the transparent electrode has a surface concavo-convex structure, the concavo-convex height difference is 10 to 100 nm, and the concavo-convex pitch is larger than the concavo-convex height difference and 25 times that The silicon-based thin film photoelectric conversion device characterized by the following is described, whereby the photoelectric conversion characteristics due to the light confinement effect are revised without causing a decrease in open-circuit voltage or a decrease in production yield. It is described that it is done. However, as in the case of Patent Documents 3 and 4, the means for realizing the surface unevenness in this process is chemical etching, so the process becomes complicated and there is a problem in mass productivity.

  On the other hand, in Patent Document 5, “in a photovoltaic device in which a transparent electrode, a photoelectric conversion unit, and a back electrode are sequentially laminated on a translucent substrate, the transparent electrode has an average particle diameter from the translucent substrate side. The photovoltaic device is characterized by having a structure in which a first layer having a large particle diameter and a second layer having a small average particle diameter are laminated. This is because light on the long wavelength side is refracted and scattered by the first layer having a large average particle diameter, short wavelength light is refracted and scattered by the second layer having a small average particle diameter, and more light is absorbed by the photoelectric conversion layer. Is. However, the electrode structures described in the examples have a problem in that absorption of free electrons cannot be avoided because both the first layer and the second layer are transparent conductive films. That is, incident light passes through the first layer film of at least 1.0 μm over the entire area of the substrate surface, and further passes through the second layer film of at least 0.2 μm, so that the absorption by the film of at least 1.2 μm as a whole is achieved. It has been found that there is a problem that the attenuation of light until it reaches the photoelectric conversion layer is unavoidable, and a significant improvement in photoelectric conversion efficiency is not recognized.

  Further, Patent Document 6 also discloses that “a silicon-based thin film photoelectric conversion device including a transparent electrode, a silicon-based thin film photoelectric conversion unit, and a back electrode including a light-reflective metal electrode, which are sequentially formed on a substrate, The transparent electrode has a two-layer structure in which first and second transparent conductive films are stacked from the substrate side, and the first transparent conductive film has an average height difference of surface irregularities of 100 to 1000 nm. A silicon-based thin film photoelectric conversion device characterized in that the conductive film has an average film thickness of 50 to 500 nm and the average height difference of the surface irregularities is smaller than that of the first transparent conductive film. Thus, even when the surface irregularity of the first transparent conductive film is severe, spike-like protrusions can be eliminated by smoothing the surface irregularity of the second transparent conductive film, and a short circuit between the junctions in the photoelectric conversion unit Reduction can be, it is described that can reduce the variation in performance of the photoelectric conversion device. However, even when this transparent electrode is used, as with the problem described in Patent Document 5, since it passes through the two-layer transparent conductive film (continuous film) having absorption, it is absorbed by the conductive film. It has been found that there is a problem that the amount of light incident on the photoelectric conversion layer is reduced and the photoelectric conversion efficiency is not improved.

  Accordingly, in order to solve the various problems described above, the present inventor has described that “a plurality of ridges and a plurality of flat portions are formed, and the surfaces of the ridge portions and the flat portions include a large number of micro convex portions. A substrate with a transparent conductive oxide film in which a continuous transparent conductive oxide film is provided on the substrate, and a photoelectric device having a back electrode on the substrate with the film through a photoelectric conversion layer "Conversion element" is proposed (see Patent Document 8).

Japanese Examined Patent Publication No. 7-105166 Japanese Patent Publication No. 6-12840 JP-A-61-288314 JP-A-61-288473 Japanese Patent Laid-Open No. 3-125481 JP 2000-252500 A JP 2000-232234 A International Publication No. 03 / 036657A1 Pamphlet

However, the substrate with a transparent conductive oxide film described in Patent Document 8 has a spectral haze ratio of 10 to 95% over the entire wavelength range of 400 to 800 nm, and the difference between the maximum value and the minimum value of the spectral haze ratio ( The maximum value-minimum value is as good as 50% or less, but the difference between the maximum value and the minimum value of the C light source haze rate (maximum value-minimum value) [hereinafter simply referred to as "variation in C light source haze rate". Say. In particular, there is a large variation in the C light source haze ratio in a substrate having a size of about 30 cm square obtained when mass-produced with a transport type CVD (for example, CVD using a belt conveyor furnace) apparatus (for example, 40%).
Therefore, the substrate with a transparent conductive oxide film having low resistance and high transparency, having good light scattering performance in the entire wavelength range of sunlight (300 nm to 3 μm), and excellent in mass productivity,
The present invention provides a substrate with a transparent conductive oxide film in which variation in haze ratio of C light source is sufficiently small even for a large substrate of 30 cm × 30 cm, and the substrate with a transparent conductive oxide film is provided. A method for producing with good productivity is provided, and furthermore, the efficiency of the photoelectric conversion rate is improved by applying the substrate with a transparent conductive oxide film as a substrate of a photoelectric conversion element, particularly a thin film silicon solar cell. It is an object to provide a photoelectric conversion element.

  As a result of intensive studies to achieve the above object, the present inventor is composed of a plurality of crests and a plurality of flat parts, and the crests and the surfaces of the flat parts continuously have a large number of micro convex parts. The substrate with a specific transparent conductive oxide film has low resistance and high transparency, has good light scattering performance in the entire wavelength range of sunlight, and is excellent in mass productivity. It has been found that the variation in the C light source haze ratio is sufficiently small even for a large substrate of 30 cm × 30 cm manufactured using the apparatus, and the present invention has been achieved. That is, the present invention provides a substrate with a transparent conductive oxide film shown in the following (1) to (10), a method for producing a substrate with a transparent conductive oxide film shown in (11) to (14), and (15) And the photoelectric conversion element shown in (16) is provided.

(1) A transparent conductive oxide film comprising a plurality of crests and a plurality of flat parts, and the crests and the surfaces of the flat parts continuously having a large number of micro-convex parts on the substrate. A substrate with a transparent conductive oxide film provided on the substrate,
The spectral haze ratio is 10 to 95% over the entire wavelength range of 400 to 800 nm, the difference between the maximum value and the minimum value of the spectral haze ratio (maximum value-minimum value) is 50% or less, When the haze ratio is measured with a haze meter, the C light source haze ratio is 30 to 90%, and the difference between the maximum value and the minimum value of the C light source haze ratio (maximum value−minimum value) is 20% or less. A substrate with a conductive oxide film.

(2) The transparent conductive oxide film is a continuous layer made of a discontinuous hill portion made of a first oxide and a second oxide formed thereon, and is formed on the surface of the continuous layer. It consists of a continuous layer having a large number of micro-convex parts continuously,
The transparent conductive material according to the above (1), wherein the distance between the apexes between the adjacent ridges (hereinafter also simply referred to as “pitch between the ridges”) is 0.7 to 1.2 μm on a straight line. Substrate with conductive oxide film.

  (3) The substrate with a transparent conductive oxide film according to (1) or (2), wherein the sheet resistance is 8 to 20Ω / □, and the transmittance at 550 nm by an immersion method is 80 to 90%. .

  The height of the peak is 0.2 to 2.0 μm, and the distance between the apexes between the adjacent peaks (hereinafter also simply referred to as “pitch between peaks”) is on a straight line. It is preferable that it is 0.7-1.2 micrometers.

  (4) Any of (1) to (3) above, wherein the convex portion has a bottom diameter of 0.1 to 0.3 μm and a height / bottom diameter ratio of 0.7 to 1.2. A substrate with a transparent conductive oxide film as described in 1.

  (5) The base body with a transparent conductive oxide according to any one of (1) to (4), wherein the bottom diameter of the small ridge is 0.2 to 2.0 μm.

  The first oxide is preferably transparent.

(6) The first oxide is comprised of at least one selected from the group consisting of SnO ₂ containing TiO _2, SnO ₂ and fluorine, the content of fluorine in the case of containing fluorine, SnO ₂ The substrate with a transparent conductive oxide film according to any one of (1) to (5), which is 0.01 mol% or less based on the weight.

  The second oxide is preferably transparent.

  It is preferable that the second oxide has conductivity.

(7) Any of the above (1) to (6), wherein the second oxide is a transparent conductive oxide containing at least one selected from the group consisting of SnO ₂ , ZnO and In ₂ O ₃ A substrate with a transparent conductive oxide film as described in 1.

(8) The second oxide is made of SnO ₂ containing fluorine, contains 0.01 to 4 mol% of fluorine with respect to SnO ₂ , and has a conductive electron density of 5 × 10 ¹⁹ to 4 × 10 ^20. The substrate with a transparent conductive oxide film according to any one of (1) to (7), which is cm ⁻³ .

  (9) The above (1) to (1), wherein an oxide layer made of an oxide having a composition different from that of the first oxide and the second oxide is formed between the small mountain portion and the continuous layer. The substrate with a transparent conductive oxide film according to any one of (8).

(10) With the transparent conductive oxide film according to (9), wherein the first oxide is SnO ₂ , the different oxide is SiO ₂ , and the second oxide is SnO ₂ containing fluorine. Substrate.

(11) The above-mentioned (1) to (1), wherein a discontinuous hill portion made of a first oxide is formed on a transparent substrate by an atmospheric pressure CVD method, and a continuous layer made of a second oxide is formed thereon. 10) The method for producing a substrate with a transparent conductive oxide film according to any one of
At least the surface of the transparent substrate is made of a material different from the first oxide,
In the atmospheric pressure CVD method, the concentration of the source gas containing the metal forming the first oxide with respect to the total gas amount of the carrier gas and the source gas forming the first oxide is 0.02 to 0.02. The first oxide is formed with respect to the total gas amount of the first CVD step for forming nuclei having a mass film thickness of 1 to 20 nm and the carrier gas and the source gas for forming the first oxide as 30% by volume. Of a substrate with a transparent conductive oxide film comprising: a second CVD step of forming a small ridge having a mass film thickness of 100 to 1000 nm with a concentration of a source gas containing metal to be 0.3 to 3.0% by volume Method.

  (12) The method for producing a substrate with a transparent conductive oxide film according to (11), wherein the small mountain portion is formed by an atmospheric pressure CVD method using tin tetrachloride, water, and hydrogen chloride.

  (13) The continuous layer made of the second oxide is formed on the transparent base on which the small ridges and the small ridges are not formed by an atmospheric pressure CVD method, as described in (11) or (12) above A method for producing a substrate with a transparent conductive oxide film.

  (14) The transparent conductive oxidation according to any one of (11) to (13), wherein an oxide layer made of the different oxide is formed between the small mountain portion and the continuous layer by an atmospheric pressure CVD method. A method for producing a substrate with a physical film.

  (15) A photoelectric conversion element having a back electrode on a substrate with a transparent conductive oxide film according to any one of (1) to (10) above via a photoelectric conversion layer.

  (16) The photoelectric conversion element according to (15), wherein the photoelectric conversion layer is formed by forming p, i, and n layers in this order.

  The back electrode is preferably a metal film containing 95 atomic% or more of Ag.

  The metal film preferably contains Pd or Au in the metal film in an amount of 0.3 to 5 atomic%.

  It is preferable to have a contact improvement layer between the photoelectric conversion layer and the back electrode.

The specific resistance of the contact improvement layer is preferably 1 × 10 ⁻² Ω · cm or less.

The absorption coefficient of the contact improvement layer is preferably 5 × 10 ³ cm ⁻¹ or less in a wavelength region of 500 to 800 nm.

  It is preferable that the contact improvement layer has zinc oxide (ZnO) as a main component, and 90 atomic% or more of all metal components in the contact improvement layer is Zn.

  The contact improving layer preferably contains gallium (Ga) or aluminum (Al) in an amount of 0.3 to 10 atomic% with respect to the sum of Zn.

  The contact improving layer is preferably formed by sputtering in an inert gas containing 0.3 to 20% by volume of carbon dioxide.

  The film formation by the sputtering method is preferably performed by tilting the target by 30 to 90 ° with respect to the substrate.

  As will be described below, according to the present invention, it has low resistance and high transparency, has good light scattering performance in the entire wavelength range of sunlight, is excellent in mass productivity, and particularly used in a transport type CVD apparatus. The substrate for a photoelectric conversion element, in particular, a thin-film silicon solar cell, can be obtained by forming a substrate with a transparent conductive oxide film having sufficiently small variation in the C light source haze ratio even for a large substrate of 30 cm × 30 cm manufactured in When used as a substrate for a substrate, it is possible to provide a substrate with a transparent conductive oxide film having a high photoelectric conversion efficiency, a method for producing the same, and a photoelectric conversion element (particularly, a solar cell) using the substrate. .

The present invention is described in detail below.
The substrate with a transparent conductive oxide film according to the first aspect of the present invention (hereinafter, also simply referred to as “substrate with a transparent conductive oxide film of the present invention”) includes a plurality of peaks and a plurality of flat portions. A substrate with a transparent conductive oxide film in which a surface of the crest and the flat portion has a continuous surface with a number of micro-convex projections provided on the substrate. There,
The spectral haze ratio is 10 to 95% over the entire wavelength range of 400 to 800 nm, the difference between the maximum value and the minimum value of the spectral haze ratio (maximum value-minimum value) is 50% or less, When the haze ratio is measured with a haze meter, the C light source haze ratio is 30 to 90%, and the difference between the maximum value and the minimum value of the C light source haze ratio (maximum value−minimum value) is 20% or less. A substrate with a conductive oxide film.

Hereinafter, the shape and configuration of the substrate with a transparent conductive oxide film of the present invention will be described in detail with reference to FIG. 1 and FIG. The photoelectric conversion element is not limited to these drawings.
FIG. 1 is a partially cutaway cross-sectional view showing the shape and configuration of a substrate with a transparent conductive oxide film of the present invention, and FIG. 2 is an enlarged view of a crest 12 shown in FIG.

As shown in FIG. 1, the substrate 10 with a transparent conductive oxide film of the present invention lies on a glass substrate 11 with macro unevenness (texture) formed by a plurality of discontinuous peaks 12 and between these peaks. It has a plurality of flat portions 13, and the ridges 12 and the outer surfaces of the flat portions 13 have a structure having a large number of micro irregularities (textures). Hereinafter, such a structure having two irregularities is referred to as a double texture structure.
Further, in the present invention, as shown in FIG. 1, the transparent conductive oxide film 14 is composed of a discontinuous small ridge portion 15 made of a first oxide and a second oxide formed thereon. And a continuous layer 16 having a large number of micro-convex portions continuously on the surface of the continuous layer, and the pitch P _c between the ridges is in a range of 30 cm or more on a straight line on the substrate. In this case, it is preferably 0.7 to 1.2 μm on a straight line, more preferably 0.9 to 1.1 μm. The continuous layer 16 made of the second oxide is continuously formed on the small ridges 15 and on the glass substrate 11 where the small ridges 15 are not formed.

In the present invention, the height H _{a of the} ridge (height from the top of the micro-projection on the flat portion) is preferably 0.2 to 2.0 μm, and 0.3 to 1. It is more preferably 0 μm, and further preferably 0.4 to 0.7 μm.
The distance of the flat portion between adjacent said crests (hereinafter, simply referred to as "distance between crest".) W _a is preferably 0~1.5μm on a straight line, 0-1. It is more preferably 0 μm, and further preferably 0.1 to 0.4 μm (all peaks are discontinuous). In the present invention, the plurality of peaks There may be a portion continuous with a discontinuous portion, that spacing W _a between crests is 0~1.5μm is a place no flat portion It may be.
Further, the pitch P _a between the peaks is the same value as the pitch P _c between the small peaks, and is preferably 0.7 to 1.2 μm on the straight line in a range of 30 cm or more on the base. 0.9 to 1.1 μm is more preferable.

In the present invention, the height H _c of the small ridge is preferably 0.2 to 2.0 μm, more preferably 0.2 to 1.0 μm, and 0.4 to 0.7 μm. More preferably it is.
Further, the distance of the flat portion between the adjacent small ridges (hereinafter also simply referred to as “interval between small ridges”) W _c is preferably 0.1 to 2.0 μm on a straight line, and More preferably, it is 5-1.5 micrometers.
Further, the bottom surface diameter D _c of the small ridges is preferably 0.2 to 2.0 [mu] m, and more preferably in 0.2 to 1.0 [mu] m.

In the present invention, the surface of the peak portion 12 and the flat portion 13, that is, the surface of the continuous layer 16 made of the second oxide has a large number of micro-convex portions 17 as shown in FIG. Yes.
The height H _b of the convex portion is preferably 0.05 to 0.2 μm, and more preferably 0.1 to 0.2 μm.
Further, the distance between the vertices between the adjacent convex portions (hereinafter, also simply referred to as “pitch P _b between convex portions”) is preferably 0.1 to 0.3 μm on a straight line. More preferably, the thickness is 1 to 0.2 μm.
Furthermore, the bottom surface diameter D _b of the convex portion is preferably 0.1 to 0.3 μm, more preferably 0.15 to 0.3 μm, and the height H _b of the convex portion / the bottom surface diameter D. The ratio of _b is preferably 0.7 to 1.2, and more preferably 0.7 to 1.0.

In FIG. 2, the thickness H _d (including the micro-projections) of the continuous layer 16 on the small ridge 15 is preferably 0.5 to 1.0 μm, and preferably 0.5 to 0.7 μm. It is more preferable that Similarly, it is preferable that the thickness H _e of the continuous layer 16 on the glass substrate 11 (including the convex portion of the micro) is 0.5 to 1.0 [mu] m, to be 0.5~0.7μm More preferred.

  In the present invention, the outer surfaces of the ridges 12 and the flat portions 13 are made to have a concavo-convex (micro concavo-convex) smaller than the concavo-convex (macro concavo-convex) due to such ridges, so that light with a short wavelength can be obtained. It is possible to scatter strongly, and it becomes possible to effectively scatter light in a wide area as a whole. That is, light having a long wavelength can be scattered by a peak having large unevenness, and light having a short wavelength can be scattered from a small uneven surface, so that high light scattering property can be achieved as a whole.

Such surface properties of the substrate with a transparent conductive oxide film of the present invention can be confirmed by, for example, the following method.
(1) Analysis of surface shape: The convex part of the film surface is observed with a scanning electron microscope (SEM), and the bottom diameter of the convex part can be measured from the obtained micrograph. Moreover, the uneven | corrugated shape of the film | membrane surface is observed with SEM and atomic force microscope (AFM), and the uneven | corrugated shape of a film | membrane surface and the height of a convex part can be analyzed from the obtained micrograph.
(2) Measurement of surface coverage: The coverage of the small oxide portion of the first oxide on the substrate is measured from the SEM photograph, and the area occupied by the small mountain portion on the substrate is the area of the entire coated surface of the substrate. The value divided by can be evaluated as the surface coverage.
The mass film thickness is prepared separately by checking the detection amount proportional to the metal amount of the metal oxide with a fluorescent X-ray apparatus for a discontinuous metal oxide in a certain area on the substrate. The film thickness obtained on the assumption that the discontinuous volume of the oxide was continuous compared to the detected amount of the fluorescent X-ray apparatus in the same kind of metal oxide with a known film thickness continuous on the substrate. Show.

Moreover, the base | substrate with a transparent conductive oxide film of this invention which has such a shape and structure has the characteristic shown below in the whole base | substrate.
That is, the substrate with a transparent conductive oxide film of the present invention has a spectral haze ratio of 10 to 95%, preferably 20 to 90% over the entire wavelength range of 400 to 800 nm, and the maximum and minimum values of the spectral haze ratio. (Maximum value−minimum value) is 50% or less, preferably 30% or less, and the C light source haze ratio when the C light source haze ratio is measured with a haze meter on the entire surface of the substrate is preferably 30 to 90%, preferably It is 40 to 80%, more preferably 40 to 70%, and the variation of the C light source haze ratio is 20% or less, preferably 10% or less.
Further, the spectral haze ratio is preferably 40 to 90% in the wavelength region of 400 to 600 nm, and particularly preferably 40 to 80% in the wavelength region of 600 to 800 nm.

Here, the “spectral haze ratio” indicates the ratio of the scattering component in the transmitted light. The haze rate depends on the wavelength, the haze rate is Hz (λ), the total transmittance is T _total (λ), the straight component of transmitted light is T _direct (λ), and the scattered component of transmitted light is T _diffuse (λ). Then, the relationship shown in the following formula is established.
T _total (λ) = T _direct (λ) + T _diffuse (λ)
・ Hz (λ) = T _diffuse (λ) / T _total (λ) × 100 [%]

The “C light source haze ratio” refers to the haze ratio measured with a C light source. In the present invention, the C light source haze measured at an interval of 10 mm when the following “variation in C light source haze ratio” is determined. Represents a rate.
Further, as described above, the “variation in C light source haze ratio” refers to the difference between the maximum value and the minimum value of the C light source haze ratio. It is the difference between the maximum value and the minimum value of the C light source haze ratio when the C light source haze ratio is measured over the entire surface of the substrate (at least an area of 0.09 m ² (for example, the entire surface of a 30 cm square substrate)).
In the present invention, “measure the C light source haze ratio over the entire surface of the substrate” means that the C light source haze ratio is measured at 10 mm intervals (except within 15 mm from the edge of the substrate) in the vertical and horizontal directions of the substrate. C light source haze ratio meter).

  Hereinafter, the substrate (transparent substrate), the first oxide, and the second oxide satisfying the shape, configuration, and characteristics of the substrate with the transparent conductive oxide film of the present invention described above will be described in detail.

<Substrate (transparent substrate)>
The substrate used for the substrate with a transparent conductive oxide film of the present invention is not necessarily flat and plate-like, and may be curved or atypical.
As such a substrate, it is preferable that at least the surface thereof is made of a material different from the first oxide described later. Specifically, a glass substrate, a ceramic substrate, a plastic substrate, a metal substrate, etc., and the surface of these substrates. In addition, those having an alkali barrier layer such as a silicon oxide film, an aluminum oxide film, a zirconium oxide film, and a titanium oxide film may be used. Among these, a transparent substrate excellent in light-transmitting property is preferable, and a glass substrate or a glass substrate provided with an alkali barrier layer is preferable from the viewpoint of strength and heat resistance.
Further, such a substrate preferably has a high transmittance in the wavelength region of 350 to 800 nm, for example, a transmittance of 80% or more, and is desirably sufficiently insulating and has high chemical and physical durability. .

Specific examples of the glass substrate include, for example, colorless and transparent soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, quartz glass, borosilicate glass substrate, alkali-free glass substrate, and other various glasses. A transparent glass plate made of can be used.
Moreover, when using the base | substrate with a transparent conductive oxide film of this invention for a board | substrate for solar cells, it is preferable from the point of intensity | strength and the transmittance | permeability that the thickness of a glass substrate is 0.2-6.0 mm. .

In the case of a glass substrate made of glass containing sodium such as soda lime silicate glass or a glass substrate made of glass containing low alkali, the diffusion of alkali components from the glass to the transparent conductive film formed on the upper surface is minimized. In order to limit this, it is preferable to use a glass substrate provided with the above-described alkali barrier layer.
Moreover, you may further have the layer for reducing the difference in the refractive index of the surface of a glass substrate, and the layer provided on it on the surface of a glass substrate.

<First oxide>
The 1st oxide which comprises the transparent conductive oxide film of the base | substrate with a transparent conductive oxide film of this invention will not be specifically limited if it is a highly transparent oxide in visible region, As a specific example, , TiO ₂ , SnO ₂ , In ₂ O ₃ , ZnO, CdO, CdIn ₂ O ₄ , CdSnO ₃ , MgIn ₂ O ₄ , CdGa ₂ O ₄ , GaInO ₃ , InGaZnO ₄ , Cd ₂ Sb ₂ O ₇ , Cd ₂ GeO ₄ , CuAlO ₂ , CuGaO ₂ , SrCu ₂ O ₂ , Al ₂ O _{3 and the} like. Of these, it is preferable to use at least one selected from the group consisting of SnO ₂ containing TiO _2, SnO ₂ and fluorine.
In the present invention, the refractive index of the first oxide that forms the hills is preferably 1.8 to 2.2 at a wavelength of 400 to 800 nm, and more preferably 1.9 to 2. 1 is preferable.

Note that, as described above, the small ridge portion made of the first oxide is a discontinuous protrusion and not a continuous film. Therefore, the transparent base portion not covered with the protrusion is naturally Since the absorption loss of incident light by the small mountain portion is zero, the amount of incident light on the photoelectric conversion layer can be increased.
These small ridges are portions that increase the haze ratio (increase the degree of light scattering), and preferably have no electrical conductivity in order to suppress absorption by free electrons and make them highly transparent. Therefore, when SnO ₂ is used as the first oxide, it may be composed of only SnO ₂ , or even when fluorine is contained, the content of fluorine is 0.01 mol% or less with respect to SnO ₂ . Preferably, the content is 0.005 mol% or less.

<Second oxide>
The second oxide constituting the transparent conductive oxide film of the substrate with the transparent conductive oxide film of the present invention is a transparent conductive oxide that is transparent in the visible light region and further has conductivity. Specific examples thereof include SnO ₂ , ZnO, In ₂ O _3, etc., and two or more of them may be used in combination, and further contain a dopant for developing conductivity. Preferably it is.
Of these, SnO ₂ preferably contains 0.01 to 4 mol% of fluorine or antimony as a dopant with respect to SnO ₂ . ZnO preferably contains at least one selected from the group consisting of boron, Al and Ga as a dopant in an amount of 0.02 to 5 mol% with respect to ZnO. In ₂ O ₃ preferably contains 0.02 to 4 mol% of Sn as a dopant with respect to In ₂ O ₃ . Note that doping using these dopants may be based on hydrogen halide. Specific examples of such a hydrogen halide include HF and HBr.
In the present invention, the refractive index of such a second oxide forming the continuous layer is preferably 1.8 to 2.2 at a wavelength of 400 to 800 nm, and further 1.9 to 2. 1 is preferable.

In addition, by using SnO ₂ containing fluorine as the second oxide, the conductive electron density is improved. As the substrate used in the solar cell, the conductive electron density is preferably ^{5 × 10 19 ~4 × 10 20} cm -3, and more preferably ^{1 × 10 20 ~2 × 10 20} cm -3. If the conductive electron density is within this range, the light absorption amount of the continuous layer made of the second oxide is small, highly transparent, and highly durable against active hydrogen species. Transparency is not impaired even by hydrogen plasma irradiation generally used for forming, which is preferable.

The first oxide and the second oxide described above may be the same oxide, and in the present invention, it is preferable to use SnO ₂ for both. Moreover, it is preferable that the refractive index of a 1st oxide and a 2nd oxide layer is comparable, and it is preferable that it is specifically 1.8-2.2. When the refractive indexes of the first oxide and the second oxide are both within this range, light reflection at the interface between the first oxide and the second oxide is controlled, and the transmittance does not decrease. To preferred.

Further, in the present invention, the first oxide and the second oxide are provided between the small hill portion made of the first oxide and the continuous layer made of the second oxide. Preferably has oxide layers composed of oxides having different compositions (hereinafter also simply referred to as “different oxide layers”).
By having such different oxide layers, a method for producing a substrate with a transparent conductive oxide film according to a second embodiment of the present invention to be described later (hereinafter also simply referred to as “the production method of the present invention”). .)), A large number of micro convex portions are easily formed on the surface of the continuous layer made of the second oxide, and a structure having a peak portion and a flat portion can be easily formed.

In addition, in such a transparent conductive oxide film having a multilayer structure having different oxide layers, it is necessary to reduce reflection at the interface of each layer and maximize the amount of incident light to the photoelectric conversion layer described later. That is, it is desirable to reduce light reflection as much as possible at each interface of the glass substrate, the small hill portion made of the first oxide, the different oxide layer, and the continuous layer made of the second oxide. To that end, it is desirable that the refractive index of the first oxide, the different oxide and the second oxide be as close as possible, or that the different oxide layers be as thin as possible when the refractive indices are separated.
Specifically, examples of such different oxides include oxides of one or more atoms selected from the group consisting of Si, Sn, Al, Zr and Ti. It is preferable to have an article as a main component. Moreover, since the different oxide needs to have high translucency, it is more preferably SiO ₂ that is non-crystalline.
In addition, it is preferable that the film thickness of a different oxide layer is 2-40 nm, and it is more preferable that it is 10-30 nm.

As described above, the substrate with a transparent conductive oxide film of the present invention is composed of a plurality of crests and a plurality of flat parts sandwiching between the crests, and the surfaces of the crests and the outer flat part are micro-projections. It is preferable that the height from the top of the substrate to the top of the peak (including the micro convex portion) is 0.8 to 3.0 [mu] m. More preferably, it is 0 μm. The sheet resistance of the entire film is preferably 8 to 20 Ω / □, more preferably 8 to 12 Ω / □, and the transmittance (transparency) at 550 nm is an immersion liquid described in detail later in Examples. When measured by the method, it is preferably 80 to 90%, more preferably 85 to 90%.
In addition, the substrate with a transparent conductive oxide film of the present invention having the above-described configuration is a photoelectric conversion element according to a third aspect of the present invention described later (hereinafter also simply referred to as “photoelectric conversion element of the present invention”). When used for a transparent electrode, light incident through the substrate is refracted and scattered by the transparent electrode, enters the photoelectric conversion unit, and passes through the photoelectric conversion unit over a long distance. As a result, a lot of light is absorbed by the photoelectric conversion unit, and the effect of improving the photoelectric conversion efficiency is obtained. In particular, when used in a solar cell, the short-circuit current can be kept high without reducing the open circuit voltage and the fill factor, so that the photoelectric conversion efficiency is improved.

In the method for producing a substrate with a transparent conductive oxide film according to the second aspect of the present invention, a discontinuous hill portion made of the first oxide is formed on a transparent substrate by an atmospheric pressure CVD method. A method for producing a substrate with a transparent conductive oxide film according to the first aspect described above by forming a continuous layer comprising a second oxide on the substrate,
At least the surface of the transparent substrate is made of a material different from the first oxide,
In the atmospheric pressure CVD method, the concentration of the source gas containing the metal forming the first oxide with respect to the total gas amount of the carrier gas and the source gas forming the first oxide is 0.02 to 0.02. The first oxide is formed with respect to the total gas amount of the first CVD step for forming nuclei having a mass film thickness of 1 to 20 nm and the carrier gas and the source gas for forming the first oxide as 30% by volume. Of a substrate with a transparent conductive oxide film comprising: a second CVD step of forming a small ridge having a mass film thickness of 100 to 1000 nm with a concentration of a source gas containing metal to be 0.3 to 3.0% by volume Is the method.
The transparent substrate, the first oxide, and the second oxide are the same as the substrate according to the first aspect described above.

Here, in the first CVD step, a carrier gas (for example, nitrogen, argon, etc.) and a source gas for forming the first oxide (for example, tin tetrachloride, titanium tetrachloride, organic titanium, water, hydrogen chloride, etc.) The concentration of the raw material gas containing the metal forming the first oxide with respect to the total gas amount is 0.02 to 0.30% by volume, preferably 0.02 to 0.15% by volume, 1 to 20 nm, Preferably, it is a step of forming nuclei (small mountain nuclei) having a mass thickness of 1 to 10 nm.
In the second CVD step, the concentration of the source gas containing the metal forming the first oxide with respect to the total gas amount of the carrier gas and the source gas forming the first oxide after the end of the first CVD step. Is 0.3 to 3.0% by volume, preferably 0.3 to 1.0% by volume, and is a step of forming a small ridge having a mass film thickness of 100 to 1000 nm, preferably 100 to 300 nm.

The atmospheric pressure CVD method for forming the ridges includes the first CVD process and the second CVD process described above, so that the pitch between the ridges is easily set to about 0.7 to 1.2 μm on a straight line. Can do.
FIG. 3 is a schematic view showing a part of the transfer type atmospheric pressure CVD apparatus. In this transport type atmospheric pressure CVD apparatus, the source gas supply part and the exhaust part are in the front-rear direction in the glass traveling direction, and the turbulent flow generated in the lower part of the exhaust hole when the core of the small ridge is formed by the first CVD process described above. This is thought to be due to the fact that it has become possible to minimize the effects of. As shown in the examples described later, this means that when the ridges are formed only under the conditions corresponding to the second CVD step, the pitch between the formed ridges is 0.1 to 2.0 μm on the straight line. It can also be confirmed from spreading.
In addition, when the pitch between the small peaks is about 0.7 to 1.2 μm on a straight line, the C light source haze ratio is set to 30 to 90% after forming the continuous layer made of the second oxide, It is preferable because the variation of the C light source haze ratio is easily 20% or less.

In the following, a preferred example of the formation of a small ridge using the atmospheric pressure CVD method in the production method of the present invention is shown, but the production method of the present invention is not limited to this.
First, a soda lime glass substrate is heated to 500 ° C. in a belt conveyor furnace, and a silica film is produced by simultaneously spraying 4 L / min of nitrogen gas containing 5 mol% of silane gas and 20 L / min of oxygen gas on the glass substrate. To do.
Next, this glass substrate with a silica film is heated to 540 ° C. in the same belt conveyor furnace, nitrogen gas is used as a carrier gas, and tin tetrachloride, methanol, water and chloride are used as raw material gases for forming the first oxide. Using hydrogen, the concentration of tin tetrachloride with respect to the total gas amount of the carrier gas and the raw material gas is set to 0.1% by volume, and a nucleus with a thickness of 5 nm is formed on the silica film. In this case, the concentration of tin tetrachloride is 0.9 vol%, and a small ridge having a mass thickness of 100 nm is formed.

In the manufacturing method of this invention, it is preferable that the surface coverage on the glass substrate of the hill part formed by this atmospheric pressure CVD method is 10 to 70%.
The surface coverage can be adjusted by controlling the amount of the hydrogen chloride gas and the water. Specifically, it is preferable to increase the rate of adding hydrogen chloride gas at the time of formation of the hill core in the atmospheric pressure CVD method (particularly, the first CVD step). The ratio of adding hydrogen chloride is represented by the molar ratio of hydrogen chloride to tin tetrachloride (hereinafter simply referred to as “HCl / SnCl ₄ ”), and HCl / SnCl ₄ is preferably 1.0 to 4.0. . When HCl / SnCl ₄ is within this range, hill nuclei are easily formed, and the surface coverage can be controlled. In particular, HCl / SnCl ₄ is preferably 2.0 to 3.0.

In the production method of the present invention, the continuous layer made of the second oxide is formed on the above-mentioned ridges and on the transparent substrate on which the ridges are not formed by atmospheric pressure CVD, electron beam vapor deposition, vacuum deposition. The method can be formed using a sputtering method or a spray method, but since a large number of micro irregularities formed on the surface of the continuous layer can be formed without an etching step, the atmospheric pressure CVD method is used. It is preferable.
Further, in the manufacturing method of the present invention, the above-mentioned different oxide layer is formed by the atmospheric pressure CVD method between the small crest portion and the transparent substrate on which the small crest portion is not formed and the continuous layer made of the second oxide. It is preferable that the transparent conductive oxide film having a peak portion and a flat portion can be easily manufactured.

In the following, an example using the atmospheric pressure CVD method is shown as a preferred example of forming the continuous layer composed of the different oxide layer and the second oxide described above, but the production method of the present invention is not limited to this. .
As the different oxide layer, in the case of using a layer made of SiO _2, a layer made of SiO _2, using the atmospheric pressure CVD method, not on and the said small ridges discontinuous small ridges made of the first oxide It is formed on a flat glass substrate.
Specifically, first, the glass substrate on which the small ridges are formed is heated to 520 ° C. in a belt conveyor furnace, and nitrogen gas 4 L / min containing 5 mol% of silane gas and oxygen gas 3 L on the glass substrate. At the same time, and a layer made of SiO ₂ which is the different oxide layer is formed by atmospheric pressure CVD.
Next, this glass substrate is heated to 540 ° C. in the same belt conveyor furnace, and simultaneously sprayed with tin tetrachloride, water, hydrogen fluoride, and methanol, and using the atmospheric pressure CVD method, the second oxide is used. A fluorine-doped SnO ₂ transparent conductive oxide film which is a continuous layer is formed.

The photoelectric conversion element which concerns on the 3rd aspect of this invention has a back surface electrode through a photoelectric converting layer on the base | substrate with a transparent conductive oxide film which concerns on the 1st aspect of this invention mentioned above. It is.
Hereinafter, an example of a preferred embodiment of the photoelectric conversion element of the present invention (hereinafter described as a solar cell) will be described in detail with reference to FIG. 4, but the solar cell of the present invention is not limited thereto. .
FIG. 4 is a partially cutaway sectional view showing an example of a preferred embodiment of the solar cell of the present invention.

As shown in FIG. 4, the solar cell 20 of the present invention includes a transparent conductive oxide film 22 used for a substrate with a transparent conductive oxide film of the present invention, a photoelectric conversion layer 26, and a glass substrate 21. And a back electrode layer 27. This configuration is one of photoelectric conversion devices that can be manufactured at a relatively low cost. The solar cell 20 is designed so that light 28 enters from the glass substrate 21 side and is absorbed mainly in the i layer 24. An electromotive force is generated between the two electrodes of the transparent conductive oxide film 22 and the back electrode 27, and electricity is extracted from the solar cell through the conductive wire 29.
Below, each structure of the solar cell 20 is explained in full detail.

In the solar cell of this invention, the photoelectric converting layer 26 can be used if it is a photoelectric converting layer which can be used for a general solar cell. The structure of the photoelectric conversion layer 26 shown in FIG. 4 is a single structure including three layers in which the p layer 23, the i layer 24, and the n layer 25 are formed in this order.
Examples of the material for the p layer include hydrogenated amorphous silicon carbide (a-SiC: H). Examples of the material for the i layer include hydrogenated amorphous silicon (a-Si: H) and crystalline silicon ( c-Si), microcrystalline silicon (μc-Si), hydrogenated amorphous silicon germanium (a-SiGe: H), and the like. Examples of the n-layer material include elemental amorphous silicon (a-Si: H), microcrystalline silicon (μc-Si), and the like.
Of these, three layers in which an a-SiC: H layer is formed as a p layer, an a-Si: H layer is formed as an i layer, and an a-Si: H layer is formed as an n layer in this order (hereinafter referred to as a p-type of a-Si). (single layer) is preferable.

Another example is a tandem electromotive layer in which another pin layer is further formed on the a-Si pin layer. Specifically, the layers formed on the a-Si pin layer are the a-Si: H layer as the p layer, the microcrystalline Si layer as the i layer, and the a-Si: H layer as the n layer. Are three layers formed in this order, or an a-Si: H layer as a p layer, an a-SiGe: H layer as an i layer, and an a-Si: H layer as an n layer in this order. A tandem electromotive layer may be mentioned.
By using a tandem electromotive layer for the photoelectric conversion layer, it becomes possible to perform photoelectric conversion of light not only at a short wavelength but also at a long wavelength side. Therefore, the substrate with the transparent conductive oxide film of the present invention has the above tandem structure. If the electromotive layer is used, the photoelectric conversion efficiency is further improved.

  The film thickness of such a photoelectric conversion layer varies depending on the type of the electromotive layer to be formed. For example, the film thickness of a p layer or an n layer formed by a plasma CVD method described later is 5 to 15 nm. The film thickness of the i layer is preferably 100 to 400 nm. The film thickness of the microcrystalline Si layer in the tandem structure is preferably 500 to 3000 nm.

Further, in the solar cell of the present invention, the electrode material of the back electrode layer 27 can be used as long as it is an electrode material of a back electrode layer that can be used for a general solar cell. Ag or an Ag alloy, Al or an Al alloy, palladium, chromium, or the like is preferably exemplified, and a metal film containing 95 atomic% or more of crystalline Ag is preferably used. By using crystalline Ag for the metal film of the back electrode, it is possible to reflect the light transmitted through the photoelectric conversion layer and return the reflected light to the photoelectric conversion layer again, thereby improving the photoelectric conversion efficiency. This is preferable because it leads to an effect.
The metal film may contain Pd and / or Au as components. The content of Pd and Au in the metal film is preferably 0.3 to 5 atom%, more preferably 0.3 to 3 atom%, respectively, with respect to the total with Ag.
Moreover, when the said back surface electrode layer is a layer which consists only of Ag, it is preferable that the sum total of impurity amount is 1 atomic% or less.

  The thickness of such a back electrode layer is preferably 100 to 1000 nm. In particular, the film thickness when the back electrode layer is Ag is preferably 150 to 250 nm. If the film thickness of the back electrode layer is within this range, the sheet resistance of the back electrode layer is low, and the curve factor of the solar cell can be kept high, which is preferable because the photoelectric conversion rate is improved. Since the light which permeate | transmitted the conversion layer can be reflected in this back surface electrode layer and the short circuit current of a solar cell can be maintained high, it is preferable from a photoelectric conversion rate improving. In particular, if the thickness of the back electrode layer is 300 nm or less, it is preferable in the back electrode layer forming step by the CVD method to be described later because the formation time of the back electrode layer is short and productivity is improved.

The solar cell of the present invention may have a contact improving layer between the back electrode layer 27 shown in FIG. 4 and the photoelectric conversion layer 26.
Below, an example of the suitable embodiment of the solar cell of this invention which has a contact improvement layer is demonstrated in detail using FIG. 5, However, The solar cell of this invention is not limited to this.
FIG. 5 is a partially cutaway cross-sectional view showing an example of a preferred embodiment of the solar cell of the present invention having a contact improving layer.

As shown in FIG. 5, the solar cell 40 of the present invention has a glass substrate 44, a transparent conductive oxide film 45, a photoelectric conversion layer 42, a contact improvement layer 41, and a back electrode 43.
The contact improvement layer 41 is between the photoelectric conversion layer 42 and the back electrode 43 and is used to improve the contact between the photoelectric conversion layer 42 and the back electrode 43.
Moreover, it is preferable that the contact improvement layer 41 has a small specific resistance and absorption coefficient. Specifically, the specific resistance is preferably 1 × 10 ⁻² Ω · cm or less, and more preferably 5 × 10 ⁻³ Ω · cm or less. When the specific resistance of the contact improvement layer 41 is within this range, it is possible to pass through the back electrode 43 without reducing the electromotive force photoelectrically converted by the photoelectric conversion layer 42.
Further, the absorption coefficient is preferably 5 × 10 ³ cm ⁻¹ or less, more preferably 2 × 10 ³ cm ⁻¹ or less in the wavelength region of 500 to 800 nm. If the absorption coefficient of the contact improvement layer 41 is within this range, the light transmitted through the photoelectric conversion layer 42 is transmitted to the back electrode 43 without being absorbed, and the light reflected by the back electrode 43 is again transmitted to the photoelectric conversion layer 42. It can be transmitted.

As a material for the contact improvement layer 41, it is preferable that ZnO is a main component, and 90 atomic% or more of all metal components in the contact improvement layer is Zn. It is more preferable to contain. By containing Ga or Al, the conductive electron density is increased, and by acting as a dopant for ZnO, there is an effect of improving the electrical conductivity of the entire contact improvement layer 41.
In addition, when Ga or Al is contained, the content is preferably 0.3 to 10 atomic%, more preferably 0.3 to 5 atomic%, based on the total with Zn. Within this range, it is possible to prevent an increase in the absorption coefficient of the contact improvement layer 41 due to an excessive increase in electrical conductivity.
Furthermore, when the contact improvement layer is a ZnO layer containing Ga or Al, it may contain impurities, and the total amount of impurities is preferably 1 atomic% or less.

  The film thickness of such a contact improving layer is preferably 5 to 200 nm, more preferably 10 to 150 nm. In particular, when the contact improving layer is a zinc oxide (hereinafter, GZO) layer doped with Ga, the film thickness is preferably 50 to 150 nm.

  As a manufacturing method for manufacturing such a solar cell of the present invention, a photoelectric film in which the photoelectric conversion layer is formed by the plasma CVD method on the substrate with the transparent conductive oxide film according to the first aspect of the present invention described above. The manufacturing method which comprises the conversion layer formation process and the back electrode layer formation process which forms the said back electrode layer after this photoelectric conversion layer formation process is mentioned.

The plasma CVD method in the photoelectric conversion layer forming step can be performed under conditions for forming a photoelectric conversion layer in a general solar cell. For example, an a-Si p-i-n layer is used in Examples described later. It can be performed under the conditions shown.
In addition, as a method for forming the photoelectric conversion layer, an RF plasma CVD method, a VHF plasma CVD method, a microwave CVD method, a hot wire cell method, a catalytic gas phase chemical deposition method (Cat-CVD method), a photo CVD method, An ECR plasma CVD method or the like may be used.

The back electrode layer forming step is a step of forming the back electrode layer on the photoelectric conversion layer, and is preferably formed using a sputtering method. In addition, before forming a back electrode layer, it is preferable to form the said contact improvement layer on the said photoelectric converting layer using a sputtering method.
Specifically, the contact improvement layer can be formed by sputtering, using GZO as a target and sputtering in an inert gas atmosphere on the photoelectric conversion layer formed by plasma CVD. .
Further, as the method for forming the contact improvement layer, a physical vapor deposition method or a chemical vapor deposition method other than the sputtering method may be used, but it is preferable to use a sputtering method which can obtain good conductive film characteristics at a lower substrate temperature. . In the embodiments described later, a direct current sputtering method is used, but this may be performed by a high frequency sputtering method.

  Similarly, the back electrode layer is formed by sputtering using a metal containing 95 atomic% or more of Ag on the contact improvement layer (a photoelectric conversion layer when there is no contact improvement layer) (hereinafter simply “ It can be formed by sputtering in an inert gas atmosphere using “Ag-based metal”) as a target.

The contact improvement layer can be formed, for example, as shown below.
First, a GZO target for forming a contact improvement layer is attached to the cathode of a DC magnetron sputtering apparatus. Further, the substrate with the transparent conductive oxide film on which the photoelectric conversion layer is formed is attached to the substrate holder. Next, after the film formation chamber is evacuated to vacuum, argon gas is introduced as a sputtering gas. As the sputtering gas, an inert gas such as He, Ne, or Kr can be used in addition to the argon gas, but an argon gas that is stable in discharge and inexpensive is preferable. Moreover, it is more preferable that it is an inert gas containing 0.3-20 volume% of carbon dioxide, More preferably, it is 0.3-10 volume%. By containing carbon dioxide, it is possible to prevent an increase in absorption coefficient due to excessive improvement in conductivity due to Ga doping.
The pressure during sputtering is suitably from 0.1 to 1.5 Pa. The residual gas pressure is preferably 1.0 × 10 ^{−5 to} 2.5 × 10 ⁻³ Pa. The substrate temperature is suitably room temperature to 200 ° C., particularly 100 to 150 ° C. from the viewpoint of solar cell characteristics.
In addition, it is preferable that the film formation by the sputtering is performed by tilting the GZO target by 30 to 90 ° with respect to the substrate because both low resistance and low absorption can be achieved.

The back electrode layer is formed in the same manner as the contact improvement layer by first attaching an Ag-based metal target for forming the back electrode layer to the cathode of the DC magnetron sputtering apparatus. Further, the substrate on which the contact improving layer is formed as described above is attached to the substrate holder. Next, after the film formation chamber is evacuated to vacuum, argon gas is introduced as a sputtering gas. As the sputtering gas, an inert gas such as He, Ne, or Kr can be used in addition to the argon gas, but an argon gas that is stable in discharge and inexpensive is preferable.
The pressure during sputtering is the same as that of the contact improvement layer, and 0.1 to 1.5 Pa is appropriate. The residual gas pressure is preferably 1.0 × 10 ^{−5 to} 2.5 × 10 ⁻³ Pa. The temperature of the substrate during sputtering is suitably from room temperature to 200 ° C., particularly from 100 to 150 ° C., from the viewpoint of adhesion between the substrate and the film. Heating the substrate during sputtering is preferable because it improves the crystallinity of Ag as the back electrode, improves the reflectivity, and lowers the resistance of the entire substrate.
Further, when an Ag layer containing Pd and / or Au is formed as the back electrode layer, it may be formed using Pd and / or Au as separate targets, respectively, or Pd having a desired composition in advance. Alternatively, an Ag alloy containing Au may be prepared and used as a target.

Below, the base | substrate with a transparent conductive oxide film and solar cell of this invention are demonstrated in detail using an Example. However, the present invention is not limited to this.
(Example 1)
As Example 1, a substrate with a transparent conductive oxide film having a double texture structure as shown below was manufactured by using the transfer type atmospheric pressure CVD apparatus shown in FIG.

<Formation of alkali barrier layer>
First, a 300 mm × 300 mm × 1.1 mm thick soda lime glass substrate is heated to 500 ° C. in a belt conveyor furnace (belt speed 1 m / min), nitrogen gas 4 L / min containing 5% by volume of silane gas, and oxygen gas 20 L A silica film was produced by simultaneously spraying / min.

<Formation of first oxide>
Next, this glass substrate with an alkali barrier layer was heated to 520 ° C. in a similar belt conveyor furnace, and tin tetrachloride, water, and hydrogen chloride gas were simultaneously sprayed onto the glass substrate to form a tin oxide nucleus having a mass thickness of 10 nm. .
At this time, tin tetrachloride was heated on 30 ° C. in advance, and nitrogen gas was bubbled at 0.46 L / min and transferred onto the glass substrate. Similarly, water was sprayed on the glass substrate by heating to 15 ° C. in advance and bubbling and transferring nitrogen gas at 6 L / min. Moreover, hydrogen chloride gas was sprayed on the glass substrate at 0.06 L / min simultaneously with the transfer of tin tetrachloride and water. The concentration of tin tetrachloride was 0.1% by volume with respect to the total amount of nitrogen gas, tin tetrachloride, water, and hydrogen chloride gas.
After the tin oxide nucleus was formed, tin tetrachloride and water were simultaneously sprayed onto the glass substrate to form SnO ₂ as the first oxide having a mass thickness of 100 nm.
At this time, tin tetrachloride was heated to 45 ° C. in advance, and nitrogen gas was bubbled onto the glass substrate by bubbling 1.2 L / min. Similarly, water was sprayed on a glass substrate by heating to 70 ° C. in advance and bubbling and transferring nitrogen gas at 3 L / min. The concentration of tin tetrachloride was 0.9% by volume with respect to the total amount of nitrogen gas and tin tetrachloride and water.

After the formation of the first oxide, when the concavo-convex shape of the film surface was observed by SEM, SnO _{2 as} the first oxide was not a continuous film but formed a small ridge portion composed of macro unevenness. all right. When the SEM image obtained by observing the substrate from directly above was image-processed and calculated, the coverage of the glass substrate surface with SnO ₂ forming the ridges was 40%, and the height H _c of the hill portions made of SnO ₂ was 0. 6～0.8Myuemu, bottom diameter D _c of the small ridges by SnO ₂ is 0.8-1.0, the interval W _c between adjacent small ridges is 0.1 to 1.0 [mu] m, the pitch between adjacent small ridges P _c was 0.7 to 1.2 μm. Further, according to the measurement method described later, the sheet resistance of the small hill portion made of the first oxide is 20 MΩ / □ or more, the transmittance at 550 nm by the immersion method is determined to be 88%, and the spectral haze ratio is a wavelength of 400 to 600 nm. It was determined to be 40 to 65% in the region and 50 to 65% in the wavelength region of 600 to 800 nm. Moreover, the C light source haze rate in a 300 mm x 300 mm base | substrate was calculated | required with the measurement method mentioned later as 50 to 60%, and the dispersion | variation in C light source haze rate were 10%.

<Formation of different oxide layers>
Next, the obtained glass substrate on which the small ridges made of the first oxide are formed is heated to 520 ° C. in the same belt conveyor furnace, soda lime glass on which the small ridges are not formed. An amorphous SiO ₂ film was formed as a different oxide layer on the substrate using atmospheric pressure CVD. The SiO ₂ film was formed under the conditions that the amount of nitrogen gas containing 5% by volume of silane gas was 0.6 L / min and the amount of oxygen gas was 3 L / min.

<Formation of second oxide layer>
Further, the glass substrate on which the different oxide layers are formed is heated to 540 ° C. in the same belt conveyor furnace, and tin tetrachloride, water, HF gas, and methanol are simultaneously sprayed to form fluorine as the second oxide layer. A doped SnO ₂ film was formed.
At this time, tin tetrachloride and methanol were heated to 45 ° C. in advance, and nitrogen gas was bubbled at 12 L / min and transferred onto the glass substrate. Further, water heated to 100 ° C. was sprayed on the glass substrate at 90 g / min and HF gas at 1 L / min. Furthermore, methanol was sprayed on a glass substrate by heating to 30 ° C. in advance, bubbling nitrogen gas at 0.1 L / min and transferring.

After the formation of the second oxide layer, the uneven shape of the film surface was observed by SEM and AFM. According to SEM observation, the fluorine-doped SnO ₂ film as the second oxide layer was a continuous layer, and the coverage of the glass substrate surface with the fluorine-doped SnO ₂ film was 100%. SEM, according to AFM observation, the height H _a of the crest portion 0.4-0.6, spacing W _a between adjacent crests is 0～0.5Myuemu, the pitch P _a between adjacent crest 0 0.7 to 1.2 μm, and the height from the top of the substrate to the top of the peak (including the micro convex portion) was 1.0 to 1.4 μm. Further, the surface of the fluorine-doped SnO ₂ film has a large number of micro irregularities, the height H _b of the convex portions is 0.1 to 0.2 μm, and the pitch P _b between the convex portions is 0.1. The bottom diameter D _b of the convex portion was 0.2 to 0.3 μm, and the height H _b / bottom diameter D _b of the convex portion was 0.7. Further, according to the measurement method described later, the sheet resistance is 11Ω / □, the transmittance at 550 nm by the immersion method is determined to be 89%, and the spectral haze ratio is 85 to 70% and 600 to 800 nm in the wavelength region of 400 to 600 nm. It was calculated | required as 70 to 40% in a wavelength range, and the difference of the maximum value and minimum value of a spectral haze rate was 45%. Moreover, the C light source haze rate in a 300 mm x 300 mm base | substrate was calculated | required by the measuring method mentioned later with 65-79%, and the dispersion | variation in C light source haze rate were 14%.

In addition, in order to quantify the fluorine content and the conductive electron density in the fluorine-doped SnO ₂ film as the second oxide layer, tin tetrachloride, water, HF gas, and methanol were sprayed onto a silica-coated glass substrate. Thus, a fluorine-doped SnO ₂ film was formed. The substrate temperature and gas flow rate were the same as the conditions for forming the second oxide layer in this example. When the obtained fluorine-doped SnO ₂ film was dissolved in hydrochloric acid containing zinc and then quantitatively analyzed by gas chromatography, the fluorine content was 0.05 mol% with respect to SnO ₂ . Moreover, it was 1.5 * 10 < ²⁰ > cm < ^-3 > when the conductive electron density was calculated | required by the measurement by the Hall effect (van der Pauw method). The film thickness of the fluorine-doped SnO ₂ film was 0.6 μm as measured with a stylus film thickness meter.

  FIG. 6 shows a photograph of the substrate surface after the second oxide layer is formed, and FIG. 7 shows an electron micrograph of the film surface after the second oxide layer is formed. 6 is a photograph of the surface of the substrate with a transparent conductive oxide film obtained in Example 1 (size: 300 mm × 300 mm), and FIG. 7 is the surface of the transparent conductive oxide film obtained in Example 1. It is an electron micrograph which shows the uneven | corrugated shape of [typical part (haze rate 78%)]. Thereby, it turned out that the base | substrate with a transparent conductive oxide film used in Example 1 has a double texture structure.

A method for measuring the sheet resistance, transmittance, spectral haze ratio, and C light source haze ratio of the obtained substrate with a transparent conductive oxide film will be described below.
Sheet resistance was measured by a four-terminal method. A substrate with a conductive oxide film is cut into a 3 cm square, and a pair of 3 cm long electrodes are mounted in parallel on the conductive oxide film so that the distance between the electrodes is 3 cm on two opposite sides. It was. Next, the resistance between the electrodes was measured with a tester to obtain sheet resistance.

  The transmittance was measured using an immersion method in order to minimize a measurement error due to the difference in the size of the irregularities on the surface of the conductive oxide substrate. The immersion method is a method in which a few drops of diiodomethane are dropped on the surface of a substrate with a conductive oxide film and the transmittance is measured by sandwiching the solution with transparent quartz glass. Since absorption by diiodomethane is mainly 400 nm or less, there is almost no absorption by diiodomethane and quartz glass in the range of 400 to 800 nm. The transmittance was measured by attaching a spectrophotometer (U3400, manufactured by Hitachi, Ltd.) with an integrating sphere (Hitachi, Ltd .: 150-0901) having an inner spherical diameter of 150 mmφ.

The spectral haze ratio was measured using a spectrophotometer (U3400, manufactured by Hitachi, Ltd.) according to JIS K 7136: 2000 (ISO 14782: 1999). The measurement wavelength range was 400 to 800 nm. First, the transmittance was measured by a regular transmission method using the light incident surface as a glass surface. The transmittance at each wavelength at this time is Td (λ). Next, an integrating sphere having an inner sphere diameter of 150 mmφ was attached, and the membrane surface of the sample was brought into close contact with the integrating sphere, and the integrating sphere transmittance was measured. The transmittance at each wavelength at this time is Tt (λ). From the above measurement results, the spectral haze rate Hz (λ) was calculated by the following equation.
Hz (λ) = (Tt (λ) −Td (λ)) × 100 / Tt (λ) [%]

  The C light source haze ratio is measured at 10 mm intervals (excluding within 15 mm from the end of the base body) in each of the vertical direction and the horizontal direction of the base body (300 mm × 300 mm) (TC-H III, manufactured by Tokyo Denshoku Co., Ltd.). The variation of the C light source haze ratio was determined from the difference between the maximum value and the minimum value of the measured C light source haze ratio.

(Comparative Example 1)
As Comparative Example 1, a substrate with a transparent conductive oxide film having a double texture structure, shown below, was manufactured using the transfer type atmospheric pressure CVD apparatus shown in FIG.

<Formation of alkali barrier layer>
First, a 300 mm × 300 mm × 1.1 mm thick soda lime glass substrate is heated to 500 ° C. in a belt conveyor furnace (belt speed 1 m / min), nitrogen gas 4 L / min containing 5% by volume of silane gas, and oxygen gas 20 L / min. The silica film was produced by spraying the minutes at the same time.

<Formation of first oxide>
Next, this glass substrate with an alkali barrier layer is heated to 540 ° C. in a similar belt conveyor furnace, and tin tetrachloride, water, and hydrogen chloride gas are simultaneously sprayed onto the glass substrate to form a first oxide having a mass thickness of 100 nm. Some SnO ₂ was formed.
At this time, tin tetrachloride and methanol were heated to 45 ° C. in advance, and nitrogen gas was bubbled at 2 L / min and transferred onto the glass substrate. Further, water heated to 100 ° C. was sprayed onto the glass substrate at 15 g / min and hydrogen chloride gas at 0.5 L / min. The concentration of tin tetrachloride was 0.5% by volume with respect to the total amount of nitrogen gas, tin tetrachloride, water, and hydrogen chloride gas.

After the formation of the first oxide, when the concavo-convex shape of the film surface was observed by SEM, SnO _{2 as} the first oxide was not a continuous film but formed a small ridge portion composed of macro unevenness. all right. When the SEM image obtained by observing the substrate from directly above was image-processed and calculated, the coverage of the glass substrate surface with SnO ₂ forming the ridges was 60%, and the height H _c of the hill portions made of SnO ₂ was 0. 4 to 0.6 μm, the bottom diameter D _c of the small ridges of SnO ₂ is 0.5 to 0.7 μm, the interval W _c between adjacent small ridges is 0.2 to 0.5 μm, and the pitch between adjacent small ridges P _c was 0.3 to 1.2 μm. Further, according to the measurement method described above, the sheet resistance of the small peak portion made of the first oxide was determined to be 20 MΩ / □ or more, and the transmittance at 550 nm by the immersion method was determined to be 88%.

<Formation of different oxide layers>
Next, the obtained glass substrate on which the small ridges made of the first oxide are formed is heated to 520 ° C. in the same belt conveyor furnace, soda lime glass on which the small ridges are not formed. An amorphous SiO ₂ film was formed as a different oxide layer on the substrate using atmospheric pressure CVD. The SiO ₂ film was formed under the conditions that the amount of nitrogen gas containing 5% by volume of silane gas was 0.6 L / min and the amount of oxygen gas was 3 L / min.

<Formation of second oxide layer>
Further, the glass substrate on which the different oxide layers are formed is heated to 540 ° C. in the same belt conveyor furnace, and tin tetrachloride, water, HF gas, and methanol are simultaneously sprayed to form fluorine as the second oxide layer. A doped SnO ₂ film was formed.
At this time, tin tetrachloride was heated to 45 ° C. in advance, and nitrogen gas was bubbled at 12 L / min and transferred onto the glass substrate. Further, water heated to 100 ° C. was sprayed onto the glass substrate at 90 g / min and HF gas at 3 L / min. Furthermore, methanol was sprayed on a glass substrate by heating to 30 ° C. in advance, bubbling nitrogen gas at 0.1 L / min and transferring.

After the formation of the second oxide layer, the uneven shape of the film surface was observed by SEM and AFM. According to SEM observation, the fluorine-doped SnO ₂ film as the second oxide layer was a continuous layer, and the coverage of the glass substrate surface with the fluorine-doped SnO ₂ film was 100%. SEM, according to AFM observation, the height H _a of the crest portion 0.1 to 0.5 [mu] m, distance W _a between adjacent crests is 0～0.4Myuemu, the pitch P _a between adjacent crest 0 .3 to 1.2 μm, and the height from the top of the substrate to the top of the peak (including the micro convex portion) was 0.5 to 1.0 μm. Further, the surface of the fluorine-doped SnO ₂ film has a large number of micro irregularities, the height H _b of the convex portions is 0.1 to 0.2 μm, and the pitch P _b between the convex portions is 0.1. The bottom diameter D _b of the convex portion was 0.2 to 0.3 μm, and the height H _b / bottom diameter D _b of the convex portion was 0.73. Further, according to the measurement method described above, the sheet resistance is 10Ω / □, the transmittance at 550 nm by the immersion method is 87%, and the spectral haze ratio is 85 to 35% and 600 to 800 nm in the wavelength region of 400 to 600 nm. It was calculated to be 35 to 15% in the wavelength region, and the difference between the maximum value and the minimum value of the spectral haze ratio was 70%. Further, according to the measurement method described above, the C light source haze ratio in the 300 mm × 300 mm base was determined to be 19 to 73%, and the variation of the C light source haze ratio was determined to be 54%.

In addition, in order to quantify the fluorine content and the conductive electron density in the fluorine-doped SnO ₂ film as the second oxide layer, tin tetrachloride, water, HF gas, and methanol were sprayed onto a silica-coated glass substrate. Thus, a fluorine-doped SnO ₂ film was formed. The substrate temperature and gas flow rate were the same as the conditions for forming the second oxide layer in this example. When the obtained fluorine-doped SnO ₂ film was dissolved in hydrochloric acid containing zinc and then quantitatively analyzed by gas chromatography, the fluorine content was 0.05 mol% with respect to SnO ₂ . Moreover, it was 1.5 * 10 < ²⁰ > cm < ^-3 > when the conductive electron density was calculated | required by the measurement by the Hall effect (van der Pauw method). The film thickness of the fluorine-doped SnO ₂ film was 0.6 μm as measured with a stylus film thickness meter.

  FIG. 8 shows a photograph of the substrate surface after the second oxide layer is formed, and FIG. 9 shows an electron micrograph of the film surface after the second oxide layer is formed. 8 is a photograph of the surface of the substrate with a transparent conductive oxide film (size: 300 mm × 300 mm) obtained in Comparative Example 1, and FIGS. 9A and 9B show the transparent conductive material obtained in Comparative Example 1. FIG. It is an electron micrograph which shows the uneven | corrugated shape of the oxide film surface [The high haze rate (65%) part and low haze rate (20%) part in FIG. 8 respectively]]. Thereby, it turned out that the base | substrate with a transparent conductive oxide film used by the comparative example 1 also has a double texture structure.

The substrate with a transparent conductive oxide film obtained in Example 1 shows little variation in the C light source haze ratio from the photograph shown in FIG. 6, and the surface state is shown in the electron micrograph of FIG. Further, FIG. 10 shows the result of measuring the pitch (P _a ) between the crests by observing the surface state with an electron micrograph at 5 points in the width direction of the obtained substrate 300 mm at intervals of 50 mm. As shown in FIG. 10, the pitch between the peaks is 0.7 to 1.2 μm at all five points, and it was found that the surface has a good oxide film surface.
On the other hand, the substrate with a transparent conductive oxide film obtained in Comparative Example 1 has a large variation in spectral haze ratio from the photograph shown in FIG. 8, and the surface state is shown in the electron micrograph of FIG. Further, FIG. 11 shows a result of measuring the pitch (P _a ) between the crests by observing the surface state with an electron micrograph at five points at intervals of 50 mm in the width direction of the obtained substrate 300 mm. As shown in FIG. 11, the pitch between the crests is in a range of 0.7 to 1.2 μm, but there are also places where the pitch is greatly deviated, and it was found that the shape of the oxide film surface is not uniform.
Moreover, in the measurement of the C light source haze ratio of the substrate with a transparent conductive oxide film obtained in Example 1 and Comparative Example 1, each measurement point at intervals of 10 mm (in the horizontal direction of the operation to measure at intervals of 10 mm in the vertical direction) A graph showing the relationship with the C light source haze ratio (%) in the measurement range) is shown in FIG. 12. As a result, the variation in the C light source haze ratio of the substrate with the transparent conductive oxide film obtained in Example 1 is shown. It was found that the variation in the C light source haze ratio of the substrate with a transparent conductive oxide film obtained in Comparative Example 1 was large.

Next, the solar cell was manufactured under the conditions shown below.
<Formation of photoelectric conversion layer>
About each base | substrate with a transparent conductive oxide film obtained in Example 1 and the comparative example 1, from the position of the range shown in FIG. 13 (description figure which shows the cutout position of the board | substrate for solar cells), respectively, the size of 40 mm x 40 mm Two to three pieces of the substrate were cut out, and a photoelectric conversion layer having a pin junction using an a-Si: H thin film was formed on the cut transparent conductive oxide film of each substrate by a plasma CVD apparatus (Shimadzu Corporation). Laminated by SLCM 14). A p-i-n junction is a p-layer, i-layer, and n-layer formed (junction) in this order. The film formation conditions of the p layer, i layer, n layer, and buffer layer (p / i buffer layer) between the p layer and i layer used in this experiment are shown in Tables 1 to 4 below.

<Formation of contact improvement layer and back electrode layer>
Next, a GZO layer as a contact improving layer was formed to a thickness of about 10 nm on the photoelectric conversion layer by a direct current magnetron sputtering method. The sputtering was performed at room temperature using a GZO target containing 5 atomic% of Ga with respect to the total amount of zinc.
The sputtering was performed by evacuating the vacuum apparatus to 10 ⁻⁴ Pa or less in advance, introducing Ar gas at 75 sccm and CO ₂ gas at 1 sccm, and setting the sputtering power to 2.4 W / cm ² . Moreover, Ga content in a GZO layer was 5 atomic% with respect to the sum total of Ga and zinc similarly to the said GZO target. The GZO layer had a specific resistance of 5 × 10 ⁻³ Ω · cm and an absorption coefficient of 1 × 10 ³ cm ⁻¹ at 500 to 800 nm.
Finally, an Ag film containing 100 atomic% crystalline Ag as a back electrode layer is formed on the GZO layer by sputtering in an Ar gas atmosphere using an Ag target (pressure during sputtering: 4 × 10 ⁻¹ Pa , Sputter power: 1.4 W / cm ² ) with a film thickness of about 200 nm, and finally a solar cell having a size of 5 mm × 5 mm (cell structure: SnO ₂ / p (SiC) in / GZO / Ag) Was prepared for each substrate cut out from each substrate with a transparent conductive oxide film obtained in Example 1 and Comparative Example 1. Table 5 below shows the film thickness of each layer of the solar cell.

Each solar cell obtained was irradiated with light with a solar simulator, and the photoelectric conversion efficiency was determined from the measurement results of the short-circuit current, open-circuit voltage, and fill factor. The solar simulator used was a CE-24 type solar simulator manufactured by Opto Research, and the irradiation light spectrum of the solar simulator at the time of IV measurement was AM (air mass) 1.5, and the light intensity was 100 mW / cm ² . In addition, the electrodes of each solar cell have an area of 0.25 cm ² , and four cells are prepared on each substrate cut into a size of 40 mm × 40 mm, and the average value of the measured values in each cell Was defined as the characteristic of each solar cell.
Table 6 below shows the open circuit voltage, short circuit current, fill factor, and photoelectric conversion efficiency of each solar cell. In Table 6 below, solar cells using the respective substrates cut out from the respective substrates with transparent conductive oxide films obtained in Example 1 are represented as Examples 2 and 3, respectively, and obtained in Comparative Example 1. The solar cells using each substrate cut out from each substrate with a transparent conductive oxide film are represented as Comparative Examples 2 to 4, respectively.

  From the results shown in Table 6, it was found that the solar cells of Examples 2 and 3 all have higher photoelectric conversion efficiency than the solar cells of Comparative Examples 2 to 4. Moreover, in the solar cells of Comparative Examples 2 to 4, although the short-circuit current was at the same level as the example, the shape of the oxide film surface on the substrate is not uniform, so the open-circuit voltage and the fill factor are reduced. It was found that even if the average value of the C light source haze ratio is about the same as that of the example, the photoelectric conversion efficiency is lowered.

FIG. 1 is a partially cutaway sectional view showing the shape and configuration of a substrate with a transparent conductive oxide film of the present invention. FIG. 2 is an enlarged view of the mountain portion 12 shown in FIG. FIG. 3 is a schematic view showing a part of a transport-type atmospheric pressure CVD apparatus. FIG. 4 is a partially cutaway sectional view showing an example of a preferred embodiment of the solar cell of the present invention. FIG. 5 is a partially cutaway cross-sectional view showing an example of a preferred embodiment of the solar cell of the present invention having a contact improving layer. FIG. 6 is a photograph of the surface of a substrate with a transparent conductive oxide film (size: 300 mm × 300 mm) obtained in Example 1. FIG. 7 is an electron micrograph showing the concavo-convex shape of the surface of the transparent conductive oxide film obtained in Example 1 [typical portion (haze ratio 78%)]. FIG. 8 is a photograph of the surface of the substrate with a transparent conductive oxide film (size: 300 mm × 300 mm) obtained in Comparative Example 1. 9A and 9B show the uneven shape of the surface of the transparent conductive oxide film obtained in Comparative Example 1 [high haze ratio (65%) and low haze ratio (20%) in FIG. 8 respectively]]. It is an electron micrograph. FIG. 10 shows the pitch (P _a ) between peaks by observing the surface state with an electron micrograph in five points at intervals of 50 mm in the width direction of the substrate with a transparent conductive oxide film obtained in Example 1, 300 mm. It is a graph showing the result of having measured. FIG. 11 shows the pitch (P _a ) between peaks by observing the surface state with 5 points at an interval of 50 mm in the width direction of the substrate with a transparent conductive oxide film 300 mm obtained in Comparative Example 1 and an electron micrograph. It is a graph showing the result of having measured. FIG. 12 shows the measurement points at 10 mm intervals in the measurement of the C light source haze ratio of the substrate with a transparent conductive oxide film obtained in Example 1 and Comparative Example 1 (the horizontal direction of the operation for measuring at 10 mm intervals in the vertical direction). It is a graph showing the relationship with C light source haze rate (%) in (measurement range). FIG. 13 is an explanatory diagram showing the cut-out position of the solar cell substrate.

Explanation of symbols

10 with transparent transparent conductive oxide film base 11 glass substrate 12 crest 13 flats 14 transparent conductive oxide film 15 distance H between the distance W _c Koyama portion between the small ridges 16 continuous layer 17 protrusion W _a crest _a crest height H _b protrusion height H _c Koyama portion of the height H _d, H _e of the continuous layer thickness D _b of the bottom surface diameter D _c Koyama portion of the convex portion between the bottom diameter P _a crest Pitch _Pb Pitch between convex portions _Pc Pitch between _small ridges 20 Solar cell 21 Transparent insulating substrate 22 Transparent conductive film 23 p layer 24 i layer 25 n layer 26 Photoelectric conversion layer 27 Back electrode 28 Light 29 Conductor 40 Solar cell Substrate 41 Contact improvement layer 42 Photoelectric conversion layer 43 Back electrode 44 Glass substrate 45 Transparent conductive oxide film

Claims (16)

A transparent conductive oxide film comprising a plurality of crests and a plurality of flat parts, and a surface of the crests and the flat part having a large number of micro-convex parts continuously provided on a substrate. A substrate with a transparent conductive oxide film,
The spectral haze ratio is 10 to 95% over the entire wavelength range of 400 to 800 nm, the difference between the maximum value and the minimum value of the spectral haze ratio (maximum value-minimum value) is 50% or less, When the haze ratio is measured with a haze meter, the C light source haze ratio is 30 to 90%, and the difference between the maximum value and the minimum value of the C light source haze ratio (maximum value−minimum value) is 20% or less. A substrate with a conductive oxide film. The transparent conductive oxide film is a continuous layer made of a discontinuous hill portion made of a first oxide and a second oxide formed thereon, and a large number of micros are formed on the surface of the continuous layer. Consisting of a continuous layer having a convex portion of
The base with a transparent conductive oxide film according to claim 1, wherein a distance between the apexes between adjacent small ridges is 0.7 to 1.2 μm on a straight line.   The substrate with a transparent conductive oxide film according to claim 1 or 2, wherein the sheet resistance is 8 to 20Ω / □, and the transmittance at 550 nm by an immersion method is 80 to 90%.   The bottom surface diameter of the said convex part is 0.1-0.3 micrometer, and ratio of height / bottom diameter is 0.7-1.2, The transparent electroconductivity in any one of Claims 1-3 A substrate with an oxide film.   The base with a transparent conductive oxide according to any one of claims 1 to 4, wherein a bottom diameter of the small ridge is 0.2 to 2.0 µm. Said first oxide comprises at least one selected from the group consisting of SnO ₂ containing TiO _2, SnO ₂ and fluorine, the content of fluorine in the case of containing fluorine, relative to SnO ₂ It is 0.01 mol% or less, The base | substrate with a transparent conductive oxide film in any one of Claims 1-5. The transparent conductive material according to claim 1, wherein the second oxide is a transparent conductive oxide containing at least one selected from the group consisting of SnO ₂ , ZnO and In ₂ O ₃ . A substrate with an oxide film. The second oxide is made of SnO ₂ containing fluorine, contains 0.01 to 4 mol% of fluorine with respect to SnO ₂ , and has a conductive electron density of 5 × 10 ¹⁹ to 4 × 10 ²⁰ cm ^−3. The substrate with a transparent conductive oxide film according to claim 1.   9. The oxide layer comprising an oxide having a composition different from that of the first oxide and the second oxide is formed between the small ridge and the continuous layer. A substrate with a transparent conductive oxide film as described in 1. The substrate with a transparent conductive oxide film according to claim 9, wherein the first oxide is SnO ₂ , the different oxide is SiO ₂ , and the second oxide is SnO ₂ containing fluorine. The discontinuous small hill portion made of the first oxide is formed on the transparent substrate by the atmospheric pressure CVD method, and the continuous layer made of the second oxide is formed thereon. A method for producing a substrate with a transparent conductive oxide film according to the description,
At least the surface of the transparent substrate is made of a material different from the first oxide,
In the atmospheric pressure CVD method, the concentration of the source gas containing the metal forming the first oxide with respect to the total gas amount of the carrier gas and the source gas forming the first oxide is 0.02 to 0.02. The first oxide is formed with respect to the total gas amount of the first CVD step for forming nuclei having a mass film thickness of 1 to 20 nm and the carrier gas and the raw material gas for forming the first oxide at 30% by volume. Of a substrate with a transparent conductive oxide film comprising: a second CVD step of forming a small ridge having a mass film thickness of 100 to 1000 nm with a concentration of a source gas containing metal to be 0.3 to 3.0% by volume Method.   The method for producing a substrate with a transparent conductive oxide film according to claim 11, wherein the small mountain portion is formed by an atmospheric pressure CVD method using tin tetrachloride, water, and hydrogen chloride.   The transparent conductive oxide film according to claim 11 or 12, wherein a continuous layer made of the second oxide is formed on the transparent base on which the small ridges and the small ridges are not formed by an atmospheric pressure CVD method. A method for manufacturing a substrate with a substrate.   The production of a substrate with a transparent conductive oxide film according to any one of claims 11 to 13, wherein an oxide layer made of the different oxide is formed between the small mountain portion and the continuous layer by an atmospheric pressure CVD method. Method.   The photoelectric conversion element which has a back surface electrode through a photoelectric converting layer on the base | substrate with a transparent conductive oxide film in any one of Claims 1-10.   The photoelectric conversion element according to claim 15, wherein the photoelectric conversion layer is formed by forming p, i, and n layers in this order.

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