JP5594078B2 - Method for producing transparent conductive substrate with surface electrode and method for producing thin film solar cell - Google Patents

Description

  The present invention relates to a method for manufacturing a transparent conductive substrate with a surface electrode in which a surface electrode film made of a transparent conductive film is formed on a translucent substrate and a method for manufacturing a thin film solar cell.

  In a thin-film solar cell that generates power by making light incident from the side of a light-transmitting substrate such as a glass substrate, an electrode on the light-incident side (hereinafter referred to as “surface electrode”) is formed on the light-transmitting substrate. A transparent conductive glass substrate is used. The surface electrode is formed of a transparent conductive film such as tin oxide, zinc oxide, indium oxide or the like alone or by stacking. In thin film solar cells, crystalline silicon thin films such as polycrystalline silicon and microcrystalline silicon, and amorphous silicon thin films are used. The development of this thin film solar cell has been vigorously conducted, and the main objective is to achieve both low cost and high performance by forming a high-quality silicon thin film on a low-cost substrate using a low-temperature process. It is said that.

  As one of the thin film solar cells described above, a surface electrode made of a transparent conductive film, a photoelectric conversion semiconductor layer in which a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer are sequentially stacked on a light-transmitting substrate; A structure having a structure in which a back electrode including a light-reflective metal electrode is sequentially formed is known. In this thin-film solar cell, a photoelectric conversion action mainly occurs in the i-type semiconductor layer. Therefore, if the i-type semiconductor layer is thin, light in a long wavelength region having a small light absorption coefficient is not sufficiently absorbed. That is, the photoelectric conversion amount is essentially limited by the film thickness of the i-type semiconductor layer. Therefore, in order to use light incident on the photoelectric conversion semiconductor layer including the i-type semiconductor layer more effectively, a surface uneven structure is provided on the surface electrode on the light incident side to scatter light into the photoelectric conversion semiconductor layer, A device has been devised to diffusely reflect the light reflected by the back electrode.

  In such a thin film solar cell, generally, a method of forming a fluorine-doped tin oxide thin film on a glass substrate as a surface electrode on the light incident side by thermal decomposition of a source gas based on a thermal CVD method (for example, Patent Document 1) The surface uneven structure is formed by reference.

  However, a tin oxide film having a surface concavo-convex structure is expensive because a high temperature process of 500 ° C. or higher is required. Further, since the specific resistance of the film is high, increasing the film thickness results in a decrease in transmittance and a decrease in photoelectric conversion efficiency.

  Therefore, a zinc oxide (AZO) film doped with Al or a zinc oxide (GZO) film doped with Ga is formed by sputtering on a base electrode made of a tin oxide film or an indium oxide (ITO) film doped with Sn. There has been proposed a method of forming a surface electrode having a surface uneven structure by etching a zinc oxide film that is easily etched (see, for example, Patent Document 2). In addition, zinc and aluminum oxide doped with Al and Ga (GAZO), which generates less arcing and particles during film formation, on a base electrode made of an indium oxide (ITO) film doped with Ti having excellent light transmittance in the near infrared region. There has also been proposed a method of forming a surface electrode having a surface uneven structure by forming a film by sputtering and etching the zinc oxide film in the same manner as in the technique of Patent Document 2 (see, for example, Patent Document 3).

  However, in the method of forming the surface uneven structure by etching, it is easy to form sharp protrusions on the uneven film, it is difficult to obtain a good photoelectric conversion semiconductor layer, and the photoelectric conversion efficiency does not increase. In addition, if cleaning after etching is insufficient, defects are likely to occur in the semiconductor layer, and it is necessary to go through a complicated cleaning process to prevent this defect, resulting in poor mass productivity.

JP-T-2-503615 JP 2000-294812 A JP 2010-34232 A

  The present invention has been proposed in view of the above problems of the prior art, and provides a method for producing a transparent conductive substrate with a surface electrode and a method for producing a thin-film solar cell with high photoelectric conversion efficiency.

  As a result of intensive studies, the present inventors have conducted heat treatment on a concavo-convex film made of a zinc oxide-based crystalline transparent conductive film formed by sputtering on a translucent glass substrate at a predetermined degree of vacuum. It has been found that the haze value (scattering transmittance / total light transmittance), which is an index of the light confinement effect, increases as the conductivity of the transparent conductive film increases.

That is, in the method for producing a transparent conductive substrate with a surface electrode according to the present invention, a transparent substrate on which an indium oxide-based transparent conductive film is formed is set to 300 ° C. or higher, and the gas pressure is 1 to 10 Pa in an environment. A transparent conductive substrate with a surface electrode in which a surface electrode having a zinc oxide-based crystalline transparent conductive film having a concavo-convex structure formed on the surface is formed on the transparent conductive film by a sputtering method, 7 × 10 ⁻³ to 1 It heat-processes at 250-550 degreeC by the vacuum degree of * 10 < ^-6 > Pa.

Moreover, the manufacturing method of the thin film solar cell which concerns on this invention is a manufacturing method of the thin film solar cell which forms a surface electrode, a photoelectric conversion semiconductor layer, and a back electrode in order on a translucent board | substrate . A transparent substrate on which a transparent conductive film is formed is set to 300 ° C. or higher, and a zinc oxide system in which a concavo-convex structure is formed on the surface of the transparent conductive film by a sputtering method in an environment with a gas pressure of 1 to 10 Pa. The transparent conductive substrate with a surface electrode on which the surface electrode having the crystalline transparent conductive film is formed is subjected to heat treatment at 250 to 550 ° C. at a vacuum degree of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa.

According to the present invention, a vacuum of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa is formed after forming a zinc oxide-based crystalline transparent conductive film having a concavo-convex structure formed on a light-transmitting substrate. A higher haze ratio can be achieved by performing heat treatment at 250 to 550 ° C. As a result, a surface electrode with a higher light confinement effect can be provided, and a thin film solar cell with higher photoelectric conversion efficiency can be obtained.

It is sectional drawing which shows the structural example of the thin film solar cell which concerns on one embodiment of this invention. It is sectional drawing which shows the structural example of the transparent conductive substrate with a surface electrode for thin film solar cells which concerns on one embodiment of this invention, (A) is an uneven structure on the surface as a surface electrode on a translucent glass substrate 1B is a cross-sectional view in which a zinc oxide-based crystalline transparent conductive film is formed, and (B) is a transparent glass substrate, an indium oxide-based transparent conductive film as a surface electrode, and a surface It is sectional drawing by which the zinc oxide type crystalline transparent conductive film in which the uneven structure was formed is laminated | stacked in order. It is a graph which shows the relationship of the haze rate before and behind heat processing in a vacuum.

Hereinafter, embodiments of the present invention (hereinafter referred to as “present embodiments”) will be described in detail in the following order with reference to the drawings.
1. Thin film solar cell 1-1. Transparent conductive substrate with surface electrode 1-2. Photoelectric conversion semiconductor layer 1-3. Back electrode 2. 2. Manufacturing method of thin film solar cell 2-1. Transparent conductive substrate with surface electrode 2-2. Photoelectric conversion semiconductor layer 2-3. 2. Back electrode Example

<1. Thin Film Solar Cell>
FIG. 1 is a cross-sectional view showing a configuration example of a thin film solar cell according to the present embodiment. The thin film solar cell 10 has a structure in which a front electrode 2, a photoelectric conversion semiconductor layer 3, and a back electrode 4 are sequentially laminated on a translucent glass substrate 1. The light to be subjected to photoelectric conversion is incident on the thin-film solar cell 10 from the translucent glass substrate 1 side as indicated by an arrow.

<1-1. Transparent conductive substrate with surface electrode>
In the transparent conductive substrate with a surface electrode (transparent conductive uneven film) according to the present embodiment, the surface electrode 2 is formed on the translucent glass substrate 1. Examples of the transparent conductive substrate with a surface electrode include a transparent conductive substrate 11a with a surface electrode shown in FIG. 2A and a transparent conductive substrate 11b with a surface electrode shown in FIG. 2B.

  The transparent conductive substrate 11a with a surface electrode is made of a zinc oxide crystalline transparent conductive film in which a concavo-convex structure is formed on the surface as the concavo-convex film 22 on the translucent glass substrate 1 by a sputtering method. Is formed. The transparent conductive substrate 11b with a surface electrode is formed on the translucent glass substrate 1 by a sputtering method as the surface electrode 2, and a concavo-convex structure on the surface as the concavo-convex film 22 and an indium oxide-based transparent conductive film as the base film 21. A laminated film is formed which is laminated in order with the zinc oxide-based crystalline transparent conductive film in which is formed. Hereinafter, the transparent conductive substrate with surface electrode 11a and the transparent conductive substrate with surface electrode 11b are collectively referred to simply as “transparent conductive substrate with surface electrode 11”.

(Translucent glass substrate)
The translucent glass substrate 1 desirably has a high transmittance in the wavelength region of 350 to 1200 nm so that the spectrum of sunlight can be transmitted. In consideration of use in an outdoor environment, it is desirable to be electrically, chemically and physically stable. Examples of such translucent glass substrate 1 include soda lime silicate glass, borate glass, low alkali-containing glass, quartz glass, and other various glasses.

  The translucent glass substrate 1 prevents diffusion of ions from the glass to the surface electrode made of a transparent conductive film formed on the upper surface thereof, and the influence on the electrical properties of the film due to the type and surface state of the glass substrate. In order to minimize this, an alkali barrier film such as a silicon oxide film may be formed on the glass substrate.

(Surface electrode)
As shown in FIG. 1, the surface electrode 2 is a surface electrode having a surface uneven structure 2a. The surface electrode 2 desirably has a high transmittance of 80% or more with respect to light having a wavelength of 350 to 1200 nm, similarly to the light-transmitting glass substrate 1. Further, the surface electrode 2 desirably has a sheet resistance (surface resistance) after heat treatment under vacuum, which will be described in detail later, of 10Ω / □ or less, and the haze ratio of the surface electrode 2 is 15% or more, more preferably 20 % Or more is desirable. Further, the upper limit of the haze ratio is preferably less than 50%. If the haze ratio exceeds 50%, the power generation efficiency decreases due to recombination and an increase in defects in the power generation layer made of silicon.

  For example, as shown in FIG. 2 (A), the surface electrode 2 can be composed of the concavo-convex film 22 alone. Moreover, the surface electrode 2 can be comprised by the laminated body laminated | stacked in order of the base film 21 and the uneven | corrugated film | membrane 22, for example, as shown to FIG. 2 (B). As will be described later in detail, since the base film 21 is an indium oxide-based transparent conductive film, the volume resistivity is lower than that of the zinc oxide-based transparent conductive film. Therefore, as in the case of the surface electrode 2 shown in FIG. 2B, by positioning the base film 21 between the translucent glass substrate 1 and the concavo-convex film 22, the same resistivity is obtained as shown in FIG. As shown in A), the thickness of the concavo-convex film 22 can be made thinner than when the surface electrode 2 is composed of the concavo-convex film 22 alone. As a result, the surface electrode 2 shown in FIG. 2B is thin as a whole, which is advantageous in terms of translucency.

  The degree of unevenness of the surface uneven structure 2a is preferably such that the haze ratio, which is an index indicating surface unevenness, is 20% or more, and the arithmetic average roughness (Ra) is preferably 40 to 120 nm. According to the surface electrode 2 having the surface concavo-convex structure 2 a having such a haze ratio and arithmetic average roughness (Ra), the light confinement effect is enhanced and the photoelectric conversion efficiency of the thin-film solar cell 10 can be improved.

(Undercoat)
The base film 21 is an indium oxide-based amorphous transparent conductive film doped with at least one selected from Ti, Sn, and Ga. In the present specification, amorphous means a material whose diffraction peak intensity in X-ray analysis is 20% or less of the crystalline diffraction peak intensity. As such an indium oxide-based amorphous transparent conductive film, for example, an indium oxide (ITO) film doped with Ti can be used. The ITiO film has a high light transmittance in the near infrared region, can easily form an amorphous film, and can promote the growth of a zinc oxide-based crystal formed thereon. In the ITiO film, the amount of doping of Ti is preferably 0.5 to 2.0% by mass.

  Further, for example, an indium oxide (ITGO) film doped with Sn or Ga may be used as the indium oxide-based amorphous transparent conductive film. As the ITGO film, an amorphous film can be easily formed, and the growth of a zinc oxide-based crystal formed thereon can be promoted. In the ITGO film, the doping amount of Sn and Ga is preferably 3.0 to 15% by mass.

  Furthermore, for example, an indium oxide (ITiTO) film doped with Ti or Sn may be used as the indium oxide-based amorphous transparent conductive film. The IToTO film can further promote the growth of the zinc oxide-based crystal as compared with the ITO film. In the IToTO film, the amount of doping Ti and Sn is preferably 0.01 to 2.0% by mass.

  The film thickness of the base film 21 is preferably 200 to 500 nm, more preferably 300 to 400 nm. When the film thickness is less than 200 nm, the effect of increasing the haze ratio by the base film 21 is significantly reduced. On the other hand, when the film thickness exceeds 500 nm, the transmittance decreases, and the light confinement effect due to the increase in the haze ratio is offset.

(Uneven film)
The uneven film 22 is a zinc oxide-based crystalline transparent conductive film doped with at least one selected from Al, Ga, B, In, F, Si, Ge, Ti, Zr, and Hf. Examples of such a zinc oxide-based crystalline transparent conductive film include a zinc oxide (GAZO) film doped with both Al and Ga, a zinc oxide (AZO) film doped with Al, and a zinc oxide doped with Ga ( GZO) film. Among these zinc oxide films, a GAZO film is more preferable because arcing hardly occurs during film formation by sputtering. In the GAZO film, the amount of doping Al and Ga is preferably 0.1 to 0.5% by mass. Further, in the GZO film, the amount of Ga doping is preferably 0.2 to 6.0% by mass.

  The film thickness of the uneven film 22 is preferably 300 to 2000 nm, more preferably 400 to 1600 nm. When the film thickness is smaller than 300 nm, the unevenness is not increased, and the haze ratio of the surface electrode 2 may be less than 10%. On the other hand, if the film thickness exceeds 2000 nm, the transmittance is remarkably lowered.

<1-2. Photoelectric conversion semiconductor layer>
In the photoelectric conversion semiconductor layer 3, a p-type semiconductor layer 31, an i-type semiconductor layer 32, and an n-type semiconductor layer 33 are sequentially stacked on the surface electrode 2. Note that the order of the p-type semiconductor layer 31 and the n-type semiconductor layer 33 may be reversed, but in a solar cell, the p-type semiconductor layer is usually disposed on the light incident side.

  The p-type semiconductor layer 31 is made of, for example, a microcrystalline silicon thin film doped with B (boron) as an impurity atom. Further, instead of microcrystalline silicon, a material such as polycrystalline silicon, amorphous silicon, silicon carbide, or silicon germanium may be used. Further, the impurity atom is not limited to B, and aluminum or the like may be used.

  The i-type semiconductor layer 32 is made of, for example, an undoped microcrystalline silicon thin film. Further, instead of microcrystalline silicon, a material such as polycrystalline silicon, amorphous silicon, silicon carbide, or silicon germanium may be used. Alternatively, a silicon-based thin film material that is a weak p-type semiconductor containing a small amount of impurities or a weak n-type semiconductor and has a sufficient photoelectric conversion function may be used.

  The n-type semiconductor layer 33 is made of, for example, n-type microcrystalline silicon doped with P (phosphorus) as impurity atoms. Further, instead of microcrystalline silicon, a material such as polycrystalline silicon, amorphous silicon, silicon carbide, or silicon germanium may be used. The impurity atom is not limited to P, and N (nitrogen) or the like may be used.

<1-3. Back electrode>
In the back electrode 4, a transparent conductive oxide film 41 and a light reflective metal electrode 42 are sequentially formed on the n-type semiconductor layer 33.

  The transparent conductive oxide film 41 is not necessarily required. However, by improving the adhesion between the n-type semiconductor layer 33 and the light-reflective metal electrode 42, the reflection efficiency of the light-reflective metal electrode 42 is improved, and the n-type semiconductor layer 41 is n-type. It has a function of protecting the semiconductor layer 33 from chemical changes.

The transparent conductive oxide film 41 is formed of at least one selected from a zinc oxide film, an indium oxide film, a tin oxide film, and the like. In particular, the conductivity is improved by doping at least one of Al and Ga in the zinc oxide film and at least one of Sn, Ti, W, Ce, Ga and Mo in the indium oxide film. preferable. The specific resistance of the transparent conductive oxide film 41 adjacent to the n-type semiconductor layer 33 is preferably 1.5 × 10 ⁻³ Ωcm or less.

<2. Manufacturing method of thin film solar cell>
Next, the manufacturing method of the thin film solar cell 10 according to the present embodiment described above will be described. As shown in FIG. 1, the thin-film solar cell 10 is formed with a front electrode 2, a photoelectric conversion semiconductor layer 3, and a back electrode 4 in this order on a translucent glass substrate 1. First, the manufacturing method of the transparent conductive substrate 11 with a surface electrode which comprises the thin film solar cell 10 is demonstrated.

<2-1. Transparent conductive substrate with surface electrode>
In the method for manufacturing the transparent conductive substrate with surface electrode 11a shown in FIG. 2 (A), for example, on the translucent glass substrate 1 by sputtering in an inert gas atmosphere such as argon under a high gas pressure environment. Then, an uneven film 22 is formed as the surface electrode 2.

  The gas pressure when forming the uneven film 22 is preferably 1 to 10 Pa. When the gas pressure is higher than 10 Pa, the film formation rate is extremely reduced in exchange for an increase in the haze rate. When the gas pressure is lower than 1 Pa, it becomes difficult to generate an uneven shape on the film surface, and the haze ratio is extremely reduced.

  Moreover, although the substrate temperature at the time of sputtering of the uneven | corrugated film | membrane 22 shall be 300 degreeC or more, it is preferable to set it as 300-550 degreeC. As long as the upper limit of the substrate temperature is equal to or lower than the softening point of the translucent glass substrate 1, a maximum of 800 ° C. is applicable. In the case of a light-transmitting glass substrate for general solar cell use, the softening point is often from 600 to 650 ° C., and when these are used, the temperature of the substrate decreases when the temperature exceeds 550 ° C. As a result, the manufacturing yield can be reduced.

  In the method for manufacturing the transparent conductive substrate 11b with surface electrode shown in FIG. 2 (B), first, the temperature of the translucent glass substrate 1 is maintained in the range of 20 to 70 ° C., and mixed with, for example, argon and oxygen as the introduced gas. A base film 21 is formed by sputtering using a gas. Even if the temperature of the translucent glass substrate 1 is lower than 20 ° C., an indium oxide-based amorphous transparent conductive film can be obtained, but it is necessary to provide a mechanism for cooling the translucent glass substrate in the sputtering apparatus. There is an increase in cost, which is not preferable. Moreover, when the temperature of the translucent glass substrate 1 exceeds 70 ° C., it is difficult to obtain an indium oxide-based amorphous transparent conductive film.

  Next, the uneven film 22 is formed on the base film 21. The concavo-convex film 22 on the transparent conductive substrate with surface electrode 11b is formed on the base film 21 by sputtering in a high gas pressure environment in an inert gas atmosphere such as argon in the same manner as the transparent conductive substrate with surface electrode 11a described above. It can be formed into a film.

Next, the obtained transparent conductive substrate 11 with a surface electrode is subjected to heat treatment at 250 to 550 ° C. in an environment of a vacuum degree of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa. By performing heat treatment at such pressure and temperature, unstable oxygen bonds in the zinc oxide crystal are removed and carriers are generated, and the conductivity of the transparent conductive film constituting the surface electrode 2 is increased. A higher haze ratio can be realized.

  In the heat treatment of the transparent conductive substrate 11 with a surface electrode, for example, using a vacuum pump, the transparent conductive substrate 11 with a surface electrode as a sample is fixed to a substrate holder, and then placed in a vacuum chamber. Heat. Examples of the heating method include a method of heating with a lamp heater.

When the degree of vacuum when heat-treating the transparent conductive substrate 11 with a surface electrode is less than 7 × 10 ⁻³ Pa, a sufficient reduction effect cannot be obtained, and as a result, an excess oxygen bonding portion remains. Therefore, the sheet resistance of the surface electrode 2 exceeds 10Ω / □, and the haze ratio of the surface electrode 2 is not improved. When the degree of vacuum during the heat treatment exceeds 1 × 10 ⁻⁶ Pa, the sheet resistance exceeds 10Ω / □ and the haze ratio of the surface electrode 2 does not improve. Moreover, when the vacuum degree at the time of heat-processing the transparent conductive substrate 11 with a surface electrode exceeds 1 * 10 < ^-6 > Pa, exhaust time becomes extremely long, productivity is bad, and it becomes difficult to apply industrially. .

  When the heating temperature at the time of heat-treating the transparent conductive substrate 11 with a surface electrode is less than 250 ° C., a sufficient reduction effect cannot be obtained, and as a result, an excess oxygen bonding portion remains and the sheet resistance becomes 10Ω / □. While exceeding, the haze rate of the surface electrode 2 is not improved. When the heating temperature exceeds 550 ° C., the film is excessively reduced and the sheet resistance exceeds 10Ω / □, and the haze ratio of the surface electrode 2 is not improved.

  The heating time in the heat treatment varies depending on the heating temperature and can be adjusted as appropriate. For example, when the heating temperature is 250 ° C., it is 30 minutes or more, and when the heating temperature is 550 ° C., it is 5 minutes or more.

Thus, in the manufacturing method of the transparent conductive substrate with a surface electrode according to the present embodiment, the concavo-convex film 22 or the base film 21 and the concavo-convex film 22 are formed on the translucent glass substrate 1 as the surface electrode 2. After film formation, heat treatment is performed at 250 to 550 ° C. under a vacuum degree of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa. Thereby, a higher haze ratio can be realized, and as a result, the surface electrode 2 having a higher light confinement effect can be provided.

FIG. 3 is a graph showing the relationship of the haze ratio before and after heat treatment (vacuum annealing treatment) under vacuum. Specifically, FIG. 3 shows the effect when heat-treated at a heat treatment temperature of 250 ° C. or 500 ° C. at a vacuum degree of 1 × 10 ⁻⁴ Pa with a transparent conductive substrate 11 with surface electrodes having different initial haze values. It is a graph which shows the result. In this transparent conductive substrate 11 with surface electrodes, a light-transmissive glass substrate 1, an ITiTO film as a base film 21, and a GAZO film as an uneven film 22 are laminated in this order. The horizontal axis of the graph represents the haze ratio of the transparent conductive substrate 11 with surface electrode before heat treatment, and the vertical axis of the graph represents the haze ratio of the transparent conductive substrate 11 with surface electrode after heat treatment. The broken line in the graph of FIG. 3 is a reference line for explaining the improvement ratio of the haze ratio before and after the heat treatment. When there is no heat treatment effect, a measurement point exists on the broken line.

  According to the results shown in FIG. 3, the heat treatment for the transparent conductive substrate 11 with surface electrode has the effect of increasing the haze ratio, but the haze for the transparent conductive substrate 11 with surface electrode that does not have haze before the heat treatment (initial). It can be seen that there is no effect of increasing the rate. It can also be seen that the effect of increasing the haze ratio of the transparent conductive substrate 11 with a surface electrode is greater when the temperature of the heat treatment is 500 ° C. than when the temperature of the heat treatment is 250 ° C.

<2-2. Photoelectric conversion semiconductor layer>
Next, the photoelectric conversion semiconductor layer 3 is formed on the surface electrode 2 in the transparent conductive substrate with surface electrode 11 by using, for example, a plasma CVD (Chemical Vapor Deposition) method in which a base temperature is set to 400 ° C. or less. As this plasma CVD method, a generally well-known parallel plate type RF plasma CVD may be used, or a plasma CVD method using a high-frequency power source having a frequency of 150 MHz or less from the RF band to the VHF band may be used.

  The photoelectric conversion semiconductor layer 3 is formed by sequentially stacking a p-type semiconductor layer 31, an i-type semiconductor layer 32, and an n-type semiconductor layer 33. If necessary, each semiconductor layer may be irradiated with pulsed laser light (laser annealing) to control the crystallization fraction and the carrier concentration.

<2-3. Back electrode>
Next, the back electrode 4 is formed on the photoelectric conversion semiconductor layer 3. The back electrode 4 is formed by sequentially laminating a transparent conductive oxide film 41 and a light reflective metal electrode 42.

  The transparent conductive oxide film 41 is formed by a method such as vacuum deposition or sputtering, and is preferably formed of a metal oxide such as ZnO or ITO.

  The light-reflective metal electrode 42 is formed by a method such as vacuum deposition or sputtering, and is preferably formed of one selected from Ag, Au, Al, Cu, and Pt, or an alloy containing these. For example, Ag having high light reflectivity is preferably formed by vacuum deposition at a temperature of 100 to 330 ° C, more preferably 200 to 300 ° C.

As described above, in the method for manufacturing the thin-film solar cell 10 according to the present embodiment, the uneven film 22 or the base film 21 and the uneven film 22 are formed as the surface electrode 2 on the translucent glass substrate 1. After film-forming, the transparent conductive substrate 11 with a surface electrode is manufactured by heat-processing at 250-550 degreeC with the vacuum degree of 7 * 10 < ^-3 > -1 * 10 < ^-6 > Pa. Thereby, even if it does not use an etching method, the surface electrode 2 which consists of favorable unevenness | corrugation can be formed, and a higher haze rate can be implement | achieved. As a result, the surface electrode 2 having a higher light confinement effect can be provided, and the thin film solar cell 10 having a higher photoelectric conversion efficiency can be obtained.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1
Under the following manufacturing conditions, a transparent conductive substrate with a surface electrode having a laminated structure of a base film made of an indium oxide-based transparent conductive film and an uneven film made of a zinc oxide-based crystalline transparent conductive film was produced.

  First, a soda lime silicate glass substrate was used as the translucent glass substrate 1, and a base film 21 and a concavo-convex film 22 were sequentially formed as a surface electrode 2 on the glass substrate. As the base film 21, an ITiTO film doped with 1% by mass of titanium oxide and 0.01% by mass of tin oxide in indium oxide is used. As the uneven film 22, 0.58% by mass of gallium oxide in zinc oxide and aluminum oxide are used. A GAZO film doped with 0.32% by mass was used.

  For the film formation, a DC magnetron sputtering method was used. The target used was a 6 inch size, and the distance between the substrate and the target was 60 mm.

  The temperature of the soda lime silicate glass substrate is set to 25 ° C., a mixed gas of argon and oxygen (argon: oxygen = 99: 1) is used as an introduction gas, and an ITiTO film is formed by sputtering to have a film thickness of 200 nm. A film was formed. Next, the temperature of the soda lime silicate glass substrate is set to 300 ° C., the sputtering power is DC 400 W, the introduced gas is 100% argon gas, the gas pressure is adjusted to 7 Pa, and the GAZO film is formed so that the total film thickness becomes 1200 nm. Formed.

  The total light transmittance of the surface electrode was measured using JASCO V-670. The sheet resistance of the surface electrode was measured using a surface resistance meter Loresta AP (manufactured by Mitsubishi Chemical Corporation, MCP-T400). The haze value of the surface electrode was measured using a haze meter (manufactured by Murakami Color Research Laboratory, HR-200). The surface electrode immediately after film formation had a sheet resistance of 9.7Ω / □, a total light transmittance of 83.4%, and a haze value of 14.7%.

A method of heat treatment under vacuum will be described. A cryopump CRYO-U10PU manufactured by ULVAC was used as a vacuum pump, and the sample was fixed to a SUS substrate holder and then placed in a vacuum chamber. Initially, without heating the substrate, evacuation was started with the main valve connecting the vacuum pump and the chamber fully opened, and heating of the substrate was started when the pressure reached 1 × 10 ⁻⁵ Pa. The heating method was controlled to 250 ° C. by heating from the back side of the SUS holder with a lamp heater. The degree of vacuum decreases at the same time as heating is started. From this point, control is started so that the degree of vacuum becomes 7 × 10 ⁻³ Pa by adjusting the degree of opening and closing of the main valve, and the substrate temperature and degree of vacuum are stabilized. Heat treatment was performed for 1 hour. When the heat treatment was completed, the lamp heater was turned off and allowed to stand until the substrate temperature decreased to 100 ° C. or lower, and then the sample was taken out by breaking the vacuum.

  As a result, after the heat treatment in vacuum, the sheet resistance value was 8.6Ω / □, the total light transmittance was 83.2%, and the haze ratio was 19.1%, and the sheet resistance and the haze ratio were improved. The total light transmittance hardly changed before and after the heat treatment.

(Examples 2 to 4)
In Example 2, the surface electrode manufactured on the glass substrate in the same procedure as in Example 1 was subjected to heat treatment in a vacuum chamber at 350 ° C. (Example 2), 450 ° C. (Example 3), and 550. The heat treatment was performed in the same manner as in Example 1 except that the temperature was changed to ° C. (Example 4).

  In Example 2, the sheet resistance value after heat treatment was 8.4Ω / □, the total light transmittance was 83.1%, and the haze ratio was 20.1%. In Example 3, the sheet resistance value after heat treatment was 7.7Ω / □, the total light transmittance was 83.0%, and the haze ratio was 21.0%. In Example 4, the sheet resistance value after heat treatment was 7.3Ω / □, the total light transmittance was 82.8%, and the haze ratio was 22.0%. In Examples 2 to 4, the sheet resistance and the haze ratio were improved, and the total light transmittance was hardly changed before and after the heat treatment.

(Example 5)
In Example 5, when heat-treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 1, the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻⁶ Pa. Similarly, heat treatment was performed.

  In Example 5, the sheet resistance value after heat treatment was 7.3Ω / □, the total light transmittance was 82.8%, and the haze ratio was 22.9%. In Example 5, sheet resistance and haze ratio improved, and the total light transmittance hardly changed before and after heat treatment.

(Examples 6 to 8)
In Examples 6-8, the temperature at the time of heat-treating the transparent surface electrode manufactured on the glass substrate in the same procedure as Example 1 in a vacuum chamber is 350 degreeC (Example 6), 450 degreeC (Example 7). ) Heat treatment was performed in the same manner as in Example 5 except that the temperature was 550 ° C. (Example 8).

  In Example 6, the sheet resistance value after heat treatment was 6.7Ω / □, the total light transmittance was 82.7%, and the haze ratio was 24.1%. In Example 7, after the heat treatment, the sheet resistance value was 6.5Ω / □, the total light transmittance was 82.6%, and the haze ratio was 22.9%. In Example 8, the sheet resistance value was 6.1Ω / □, the total light transmittance was 82.4%, and the haze ratio was 26.4% after the heat treatment. In Examples 6 to 8, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Comparative Example 1)
In the comparative example 1, when heat-treating the surface electrode manufactured on the glass substrate in the same procedure as the example 1, the vacuum degree in the vacuum chamber was set to 1 × 10 ⁻² Pa, and the example 1 Similarly, heat treatment was performed.

  In Comparative Example 1, the sheet resistance value after heat treatment was 10.5Ω / □, the total light transmittance was 83.5%, and the haze ratio was 14.7%. In Comparative Example 1, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 2 to 4)
In Comparative Examples 2-4, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 1 in a vacuum chamber is 350 degreeC (comparative example 2), 450 degreeC (comparative example 3). Heat treatment was performed in the same manner as in Comparative Example 1 except that the temperature was 550 ° C. (Comparative Example 4).

  In Comparative Example 2, the sheet resistance value after the heat treatment was 10.1Ω / □, the total light transmittance was 83.5%, and the haze ratio was 15.4%. In Comparative Example 3, the sheet resistance value after the heat treatment was 10.0Ω / □, the total light transmittance was 83.4%, and the haze ratio was 14.7%. In Comparative Example 4, the sheet resistance value after heat treatment was 10.7Ω / □, the total light transmittance was 83.6%, and the haze ratio was 16.9%.

  In Comparative Examples 2 and 3, the effect of improving sheet resistance and haze ratio was not observed. In Comparative Example 4, the effect of improving sheet resistance was not observed.

(Comparative Examples 5 and 6)
In Comparative Examples 5 and 6, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 1 in the vacuum chamber was 200 ° C. (Comparative Example 5) and 600 ° C. (Comparative Example 6). A heat treatment was performed in the same manner as in Example 1 except that.

  In Comparative Example 5, the sheet resistance value after the heat treatment was 12.3Ω / □, the total light transmittance was 84.1%, and the haze ratio was 13.2%. In Comparative Example 5, the effect of improving sheet resistance and haze ratio was not observed.

  In Comparative Example 6, the sheet resistance value after heat treatment was 11.5Ω / □, the total light transmittance was 83.9%, and the haze ratio was 17.6%. In Comparative Example 6, the effect of improving the sheet resistance was not observed.

(Comparative Examples 7 and 8)
In Comparative Examples 7 and 8, the temperature when heat treating the surface electrode produced on the glass substrate in the same procedure as in Example 1 in the vacuum chamber was 200 ° C. (Comparative Example 7) and 600 ° C. (Comparative Example 8). A heat treatment was performed in the same manner as in Example 5 except that.

  In Comparative Example 7, the sheet resistance value after heat treatment was 11.5Ω / □, the total light transmittance was 83.7%, and the haze ratio was 14.6%. In Comparative Example 7, the effect of improving sheet resistance and haze ratio was not observed.

  In Comparative Example 8, the sheet resistance value after heat treatment was 17.8Ω / □, the total light transmittance was 83.4%, and the haze ratio was 19.4%. In Comparative Example 8, the effect of improving sheet resistance was not observed.

Example 9
In Example 9, an ITiO film in which 1% by mass of titanium oxide is doped into indium oxide is used as the base film 21, and the uneven film 22 is 0.58% by mass of gallium oxide and 0.32% by mass of aluminum oxide in zinc oxide. A GAZO film doped with is used.

  In Example 9, the temperature of the soda lime silicate glass substrate is set to 25 ° C., a mixed gas of argon and oxygen (argon: oxygen = 99: 1) is used as the introduction gas, and the film thickness is 250 nm by sputtering. Thus, an ITiO film was formed. Next, the temperature of the soda lime silicate glass substrate is set to 300 ° C., the sputtering power is DC 400 W, the introduced gas is argon gas 100%, the gas pressure is adjusted to 7 Pa, and the GAZO film is formed so that the total film thickness becomes 1250 nm. Formed.

The surface electrode manufactured on the glass substrate thus obtained was heated to 250 ° C. in a vacuum chamber, and at the same time, heat treatment was performed while maintaining the degree of vacuum at 7 × 10 ⁻³ Pa for 1 hour. .

  In Example 9, after heat treatment, the sheet resistance value was 8.9Ω / □, the total light transmittance was 83.8%, and the haze ratio was 17.8%. In Example 9, the sheet resistance and haze ratio were The total light transmittance was hardly changed before and after the heat treatment.

(Examples 10 to 12)
In Examples 10-12, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 9 in a vacuum chamber is 350 degreeC (Example 10), 450 degreeC (Example 11). Heat treatment was performed in the same manner as in Example 9 except that the temperature was 550 ° C. (Example 12).

  In Example 10, after the heat treatment, the sheet resistance value was 8.5Ω / □, the total light transmittance was 83.7%, and the haze ratio was 18.6%. In Example 11, after the heat treatment, the sheet resistance value was 8.4Ω / □, the total light transmittance was 83.6%, and the haze ratio was 19.5%. In Example 12, the sheet resistance value after heat treatment was 7.6Ω / □, the total light transmittance was 83.4%, and the haze ratio was 20.4%.

  In Examples 10 to 12, the sheet resistance and the haze ratio were improved, and the total light transmittance was hardly changed before and after the heat treatment.

(Example 13)
In Example 13, the heat treatment was performed in the same manner as in Example 9 except that the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻⁶ Pa when the heat treatment was performed.

  In Example 13, the sheet resistance value after heat treatment was 7.8Ω / □, the total light transmittance was 83.5%, and the haze ratio was 21.3%. In Example 13, sheet resistance and haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 14 to 16)
In Examples 14-16, the temperature at the time of heat treatment in the vacuum chamber was 350 ° C. (Example 14), 450 ° C. (Example 15), and 550 ° C. (Example 16). Similarly, heat treatment was performed.

  In Example 14, the sheet resistance value after heat treatment was 7.1 Ω / □, the total light transmittance was 83.3%, and the haze ratio was 22.4%. In Example 15, the sheet resistance value after heat treatment was 6.9Ω / □, the total light transmittance was 83.2%, and the haze ratio was 21.3%. In Example 16, the sheet resistance value after the heat treatment was 6.4Ω / □, the total light transmittance was 83.1%, and the haze ratio was 24.5%. In Examples 14 to 16, the sheet resistance and the haze ratio were improved, and the total light transmittance was hardly changed before and after the heat treatment.

(Comparative Example 9)
In Comparative Example 9, when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 9, the vacuum degree in the vacuum chamber was set to 1 × 10 ⁻² Pa, and Example 9 and Similarly, heat treatment was performed.

  In Comparative Example 9, the sheet resistance value after the heat treatment was 10.1Ω / □, the total light transmittance was 84.0%, and the haze ratio was 14.8%. In Comparative Example 9, the effect of improving the sheet resistance and haze ratio was not observed.

(Comparative Examples 10-12)
In Comparative Examples 10-12, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 9 in a vacuum chamber is 350 degreeC (comparative example 10), 450 degreeC (comparative example 11). Heat treatment was performed in the same manner as in Comparative Example 9 except that the temperature was 550 ° C. (Comparative Example 12).

  In Comparative Example 10, the sheet resistance value after the heat treatment was 10.6Ω / □, the total light transmittance was 84.1%, and the haze ratio was 15.5%. In Comparative Example 11, the sheet resistance value after heat treatment was 10.1Ω / □, the total light transmittance was 84.0%, and the haze ratio was 15.3%. In Comparative Examples 10 and 11, no effect of improving sheet resistance and haze ratio was observed.

  In Comparative Example 12, the sheet resistance value after the heat treatment was 10.2 Ω / □, the total light transmittance was 83.9%, and the haze ratio was 17.0%. In Comparative Example 12, the effect of improving sheet resistance was not observed.

(Comparative Examples 13 and 14)
In Comparative Examples 13 and 14, the heat treatment was performed in the same manner as in Example 9 except that the temperature during the heat treatment in the vacuum chamber was 200 ° C. (Comparative Example 13) and 600 ° C. (Comparative Example 14).

  In Comparative Example 13, the sheet resistance value after the heat treatment was 12.1Ω / □, the total light transmittance was 84.6%, and the haze ratio was 14.7%. In Comparative Example 14, the sheet resistance value after heat treatment was 20.5Ω / □, the total light transmittance was 84.4%, and the haze ratio was 15.2%. In Comparative Examples 13 and 14, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 15 and 16)
In Comparative Examples 15 and 16, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 9 in the vacuum chamber was 200 ° C. (Comparative Example 15) and 600 ° C. (Comparative Example 16). A heat treatment was performed in the same manner as in Example 13 except that.

  In Comparative Example 15, the sheet resistance value after heat treatment was 11.4Ω / □, the total light transmittance was 84.2%, and the haze ratio was 16.0%. In Comparative Example 15, the effect of improving sheet resistance and haze ratio was not observed.

  In Comparative Example 16, the sheet resistance value after heat treatment was 15.4Ω / □, the total light transmittance was 84.0%, and the haze ratio was 21.3%. In Comparative Example 16, the effect of improving sheet resistance was not observed.

(Example 17)
In Example 17, an ITGO film doped with 3.4% by mass of gallium oxide and 10% by mass of tin oxide was used as the base film 21, and 0.58% by mass of gallium oxide in zinc oxide and aluminum oxide were used as the concavo-convex film 22. A GAZO film doped with 0.32% by mass was used.

  The temperature of the soda lime silicate glass substrate is set to 25 ° C., and a mixed gas of argon and oxygen (argon: oxygen = 99: 1) is used as an introduction gas, and an ITiO film is formed by sputtering to have a film thickness of 150 nm. A film was formed. Next, the temperature of the soda lime silicate glass substrate is set to 300 ° C., the sputtering power is DC 400 W, the introduced gas is 100% argon gas, the gas pressure is adjusted to 7 Pa, and the GAZO film is formed so that the total film thickness becomes 1150 nm. Formed.

The surface electrode manufactured on the glass substrate thus obtained was heated to 250 ° C. in a vacuum chamber, and at the same time, heat treatment was performed while maintaining the degree of vacuum at 7 × 10 ⁻³ Pa for 1 hour. .

  In Example 17, the sheet resistance value was 8.5Ω / □, the total light transmittance was 82.2%, and the haze ratio was 18.3% after the heat treatment. In Example 17, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 18 to 20)
In Examples 18-20, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 17 in a vacuum chamber is 350 degreeC (Example 18), 450 degreeC (Example 19). A heat treatment was performed in the same manner as in Example 17 except that the temperature was 550 ° C. (Example 20).

  In Example 18, after the heat treatment, the sheet resistance value was 8.3Ω / □, the total light transmittance was 82.2%, and the haze ratio was 19.2%. In Example 19, the sheet resistance value after heat treatment was 7.6Ω / □, the total light transmittance was 82.0%, and the haze ratio was 20.1%. In Example 20, the sheet resistance value after heat treatment was 7.4Ω / □, the total light transmittance was 81.9%, and the haze ratio was 21.0%. In Examples 18 to 20, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Example 21)
In Example 21, when heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 17, the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻⁶ Pa, and Example 17 Similarly, heat treatment was performed.

  In Example 21, the sheet resistance value after heat treatment was 7.2 Ω / □, the total light transmittance was 81.9%, and the haze ratio was 21.9%. In Example 21, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 22 to 24)
In Examples 22-24, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 17 in a vacuum chamber is 350 degreeC (Example 22), 450 degreeC (Example 23). Heat treatment was performed in the same manner as in Example 21 except that the temperature was 550 ° C. (Example 24).

  In Example 22, the sheet resistance value after heat treatment was 6.9Ω / □, the total light transmittance was 81.8%, and the haze ratio was 23.0%. In Example 23, the sheet resistance value after heat treatment was 6.6Ω / □, the total light transmittance was 81.7%, and the haze ratio was 21.9%. In Example 24, the sheet resistance value after heat treatment was 6.0Ω / □, the total light transmittance was 81.4%, and the haze ratio was 25.2%. In Examples 22 to 24, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Comparative Example 17)
In the comparative example 17, when heat-treating the surface electrode manufactured on the glass substrate in the same procedure as the example 17, the vacuum degree in the vacuum chamber was set to 1 × 10 ⁻² Pa, and the example 17 Similarly, heat treatment was performed.

  In Comparative Example 17, the sheet resistance value after heat treatment was 10.7Ω / □, the total light transmittance was 82.6%, and the haze ratio was 14.6%, and no effect of improving the sheet resistance and haze ratio was observed.

(Comparative Examples 18-20)
In Comparative Examples 18-20, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 17 in the vacuum chamber was 350 ° C. (Comparative Example 18) and 450 ° C. (Comparative Example 19). The heat treatment was performed in the same manner as in Comparative Example 17 except that the heat treatment was performed at 550 ° C. (Comparative Example 20).

  In Comparative Example 18, the sheet resistance value after the heat treatment was 10.1Ω / □, the total light transmittance was 82.5%, and the haze ratio was 15.3%. In Comparative Example 19, the sheet resistance value after the heat treatment was 10.2 Ω / □, the total light transmittance was 84.0%, and the haze ratio was 14.6%. In Comparative Example 20, the sheet resistance value after the heat treatment was 10.4Ω / □, the total light transmittance was 82.6%, and the haze ratio was 16.8%. In Comparative Examples 18 to 20, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 21 and 22)
In Comparative Examples 21 and 22, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 17 in the vacuum chamber was 200 ° C. (Comparative Example 21), 600 ° C. (Comparative Example 22). A heat treatment was performed in the same manner as in Example 17 except that.

  In Comparative Example 21, the sheet resistance value after heat treatment was 11.5Ω / □, the total light transmittance was 83.2%, and the haze ratio was 16.2%. In Comparative Example 22, the sheet resistance value was 14.4Ω / □, the total light transmittance was 82.9%, and the haze ratio was 14.3% after the heat treatment. In Comparative Examples 21 and 22, the sheet resistance and the haze ratio were not improved.

(Comparative Examples 23 and 24)
In Comparative Examples 23 and 24, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 17 in the vacuum chamber was 200 ° C. (Comparative Example 23) and 600 ° C. (Comparative Example 24). A heat treatment was performed in the same manner as in Example 21 except that.

  In Comparative Example 23, the sheet resistance value after heat treatment was 10.7Ω / □, the total light transmittance was 82.8%, and the haze ratio was 15.8%. In Comparative Example 23, the effect of improving sheet resistance and haze ratio was not observed.

  In Comparative Example 24, the sheet resistance value after heat treatment was 25.7Ω / □, the total light transmittance was 82.5%, and the haze ratio was 21.0%. In Comparative Example 24, the effect of improving sheet resistance was not observed.

(Example 25)
In Example 25, the base film 21 was not used, and the uneven film 22 was an AZO film in which zinc oxide was doped with 2.0% by mass of aluminum oxide. The temperature of the soda lime silicate glass substrate was set to 300 ° C., the sputtering power was DC 400 W, the introduced gas was argon gas 100%, the gas pressure was adjusted to 7 Pa, and an AZO film was formed to a total film thickness of 2400 nm. The surface electrode manufactured on the obtained glass substrate was heated to 250 ° C. in a vacuum chamber, and at the same time, held for 1 hour so that the degree of vacuum was 7 × 10 ⁻³ Pa, and was subjected to heat treatment.

  In Example 25, after the heat treatment, the sheet resistance value was 8.8Ω / □, the total light transmittance was 81.3%, and the haze ratio was 17.1%. In Example 25, the sheet resistance and the haze ratio were improved, and the total light transmittance was hardly changed before and after the heat treatment.

(Examples 26 to 28)
In Examples 26 to 28, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 25 in the vacuum chamber was 350 ° C. (Example 26) and 450 ° C. (Example 27). A heat treatment was performed in the same manner as in Example 25 except that the temperature was 550 ° C. (Example 28).

  In Example 26, the sheet resistance value after heat treatment was 8.7Ω / □, the total light transmittance was 81.2%, and the haze ratio was 18.0%. In Example 27, the sheet resistance value after thermal treatment was 8.5Ω / □, the total light transmittance was 81.1%, and the haze ratio was 18.8%. In Example 28, the sheet resistance value after heat treatment was 8.4Ω / □, the total light transmittance was 81.0%, and the haze ratio was 19.7%. In Examples 26 to 28, the sheet resistance and the haze ratio were improved, and the total light transmittance was hardly changed.

(Example 29)
In Example 29, except that the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻⁶ Pa when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 25, Similarly, heat treatment was performed.

  In Example 29, the sheet resistance value after heat treatment was 8.1Ω / □, the total light transmittance was 80.9%, and the haze ratio was 20.6%. In Example 29, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 30 to 32)
In Examples 30 to 32, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 25 in the vacuum chamber was 350 ° C. (Example 30), 450 ° C. (Example 31). Heat treatment was performed in the same manner as in Example 29 except that the temperature was 550 ° C. (Example 32).

  In Example 30, the sheet resistance value after heat treatment was 7.6Ω / □, the total light transmittance was 80.8%, and the haze ratio was 21.6%. In Example 31, the sheet resistance value after heat treatment was 7.3Ω / □, the total light transmittance was 80.7%, and the haze ratio was 20.6%. In Example 32, the sheet resistance value after heat treatment was 6.8Ω / □, the total light transmittance was 80.5%, and the haze ratio was 23.6%. In Examples 30 to 32, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Comparative Example 25)
In Comparative Example 25, when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 25, except that the degree of vacuum in the vacuum chamber was 1 × 10 ⁻² Pa, Example 25 and Similarly, heat treatment was performed.

  In Comparative Example 25, the sheet resistance value after the heat treatment was 10.2 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 14.9%. In Comparative Example 25, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 26 to 28)
In Comparative Examples 26 to 28, the temperatures at which the surface electrodes manufactured on the glass substrate in the same procedure as in Example 25 were heat-treated in a vacuum chamber were 350 ° C. (Comparative Example 26) and 450 ° C. (Comparative Example 27). Heat treatment was performed in the same manner as in Comparative Example 25 except that the temperature was 550 ° C. (Comparative Example 28).

  In Comparative Example 26, the sheet resistance value after heat treatment was 11.0Ω / □, the total light transmittance was 81.4%, and the haze ratio was 15.6%. In Comparative Example 27, the sheet resistance value after the heat treatment was 10.6 Ω / □, the total light transmittance was 81.4%, and the haze ratio was 14.9%. In Comparative Example 28, the sheet resistance value after heat treatment was 10.2 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 17.1%. In Comparative Examples 26 to 28, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 29 and 30)
In Comparative Examples 29 and 30, the temperature at which the surface electrode manufactured on the glass substrate in the same procedure as in Example 25 was heat-treated in the vacuum chamber was 200 ° C. (Comparative Example 29) and 600 ° C. (Comparative Example 30). A heat treatment was performed in the same manner as in Example 25 except that.

  In Comparative Example 29, the sheet resistance value after heat treatment was 12.1Ω / □, the total light transmittance was 81.9%, and the haze ratio was 16.2%. In Comparative Example 30, the sheet resistance value after heat treatment was 56.8Ω / □, the total light transmittance was 81.8%, and the haze ratio was 14.3%. In Comparative Examples 29 and 30, the sheet resistance and the haze ratio were not improved.

(Comparative Examples 31, 32)
In Comparative Examples 31 and 32, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 25 in the vacuum chamber was 200 ° C. (Comparative Example 31) and 600 ° C. (Comparative Example 32). A heat treatment was performed in the same manner as in Example 29 except that.

  In Comparative Example 31, the sheet resistance value after heat treatment was 11.3Ω / □, the total light transmittance was 81.5%, and the haze ratio was 16.1%. In Comparative Example 31, no effect of improving sheet resistance and haze ratio was observed.

  In Comparative Example 32, the sheet resistance value after heat treatment was 45.2 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 21.5%. In Comparative Example 32, the effect of improving sheet resistance was not observed.

(Example 33)
In Example 33, the underlying film 21 was not used, and a GAZO film in which zinc oxide was doped with 0.58 mass% gallium oxide and 0.32 mass% aluminum oxide was used as the uneven film 22. The temperature of the soda lime silicate glass substrate was set to 300 ° C., the sputtering power was DC 400 W, the introduced gas was argon gas 100%, the gas pressure was adjusted to 7 Pa, and an AZO film was formed to a total film thickness of 2100 nm. The obtained surface electrode was heated to 250 ° C. in a vacuum chamber, and at the same time, kept for 1 hour so that the degree of vacuum was 7 × 10 ⁻³ Pa.

  In Example 33, the sheet resistance value was 8.7 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 16.8% after the heat treatment. In Example 33, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 34 to 36)
In Examples 34 to 36, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 33 in the vacuum chamber was 350 ° C. (Example 34), 450 ° C. (Example 35). A heat treatment was performed in the same manner as in Example 33 except that the temperature was 550 ° C. (Example 36).

  In Example 34, the sheet resistance value after heat treatment was 8.7Ω / □, the total light transmittance was 81.1%, and the haze ratio was 17.6%. In Example 35, the sheet resistance value after thermal treatment was 8.5Ω / □, the total light transmittance was 81.1%, and the haze ratio was 18.5%. In Example 36, the sheet resistance value after heat treatment was 8.4Ω / □, the total light transmittance was 81.0%, and the haze ratio was 19.3%. In Examples 34 to 36, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Example 37)
In Example 37, except that the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻⁶ Pa when heat treating the surface electrode manufactured on the glass substrate in the same procedure as Example 33, Similarly, heat treatment was performed.

  In Example 37, the sheet resistance value after thermal treatment was 8.2Ω / □, the total light transmittance was 81.0%, and the haze ratio was 20.1%. In Example 37, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 38 to 40)
In Examples 38-40, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 33 in a vacuum chamber is 350 degreeC (Example 38), 450 degreeC (Example 39). Heat treatment was performed in the same manner as in Example 37 except that the temperature was 550 ° C. (Example 40).

  In Example 38, the sheet resistance value after heat treatment was 7.8Ω / □, the total light transmittance was 80.9%, and the haze ratio was 21.2%. In Example 39, the sheet resistance value after heat treatment was 7.2Ω / □, the total light transmittance was 80.7%, and the haze ratio was 20.1%. In Example 40, the sheet resistance value after heat treatment was 6.8Ω / □, the total light transmittance was 80.6%, and the haze ratio was 23.2%. In Examples 38 to 40, the sheet resistance and the haze ratio were improved, and the total light transmittance was hardly changed before and after the heat treatment.

(Comparative Example 33)
In Comparative Example 33, when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 33, the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻² Pa. Similarly, heat treatment was performed.

  In Comparative Example 33, the sheet resistance value after heat treatment was 10.6 Ω / □, the total light transmittance was 81.4%, and the haze ratio was 14.6%. In Comparative Example 33, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 34 to 36)
In Comparative Examples 34 to 36, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 33 in the vacuum chamber was 350 ° C. (Comparative Example 34) and 450 ° C. (Comparative Example 35). Heat treatment was performed in the same manner as Comparative Example 33 except that the temperature was 550 ° C. (Comparative Example 36).

  In Comparative Example 34, the sheet resistance value after the heat treatment was 10.2 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 15.3%. In Comparative Example 35, the sheet resistance value after the heat treatment was 10.2 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 14.6%. In Comparative Example 36, the sheet resistance value after heat treatment was 10.6 Ω / □, the total light transmittance was 81.4%, and the haze ratio was 16.8%. In Comparative Examples 34 to 36, the sheet resistance and the haze ratio were not improved.

(Comparative Examples 37 and 38)
In Comparative Examples 37 and 38, the temperature at the time of heat-treating the surface electrode produced on the glass substrate in the same procedure as in Example 33 in the vacuum chamber was 200 ° C. (Comparative Example 37) and 600 ° C. (Comparative Example 38). A heat treatment was performed in the same manner as in Example 33 except that.

  In Comparative Example 37, the sheet resistance value after heat treatment was 12.1Ω / □, the total light transmittance was 81.9%, and the haze ratio was 16.2%. In Comparative Example 38, the sheet resistance value after heat treatment was 22.3Ω / □, the total light transmittance was 81.7%, and the haze ratio was 14.3%. In Comparative Examples 37 and 38, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 39 and 40)
In Comparative Examples 39 and 40, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 33 in the vacuum chamber was 200 ° C. (Comparative Example 39) and 600 ° C. (Comparative Example 40). Except for the above, heat treatment was performed in the same manner as in Example 37.

  In Comparative Example 39, the sheet resistance value after heat treatment was 11.8Ω / □, the total light transmittance was 81.6%, and the haze ratio was 15.8%. In Comparative Example 39, the effect of improving sheet resistance and haze ratio was not observed.

  In Comparative Example 40, the sheet resistance value after thermal treatment was 15.3Ω / □, the total light transmittance was 81.3%, and the haze ratio was 21.0%. In Comparative Example 40, the effect of improving the sheet resistance was not observed.

(Example 41)
In Example 41, the base film 21 was not used, and the uneven film 22 was a GZO film in which zinc oxide was doped with 3.4% by mass of gallium oxide. The temperature of the soda lime silicate glass substrate was set to 300 ° C., the sputtering power was DC 400 W, the introduced gas was argon gas 100%, the gas pressure was adjusted to 7 Pa, and an AZO film was formed to a total film thickness of 2200 nm. The obtained surface electrode was heated to 250 ° C. in a vacuum chamber, and at the same time, kept for 1 hour so that the degree of vacuum was 7 × 10 ⁻³ Pa.

  In Example 41, the sheet resistance value was 9.2Ω / □, the total light transmittance was 81.2%, and the haze ratio was 17.2% after the heat treatment. In Example 41, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 42 to 44)
In Examples 42 to 44, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 41 in the vacuum chamber was 350 ° C. (Example 42), 450 ° C. (Example 43). A heat treatment was performed in the same manner as in Example 41 except that the temperature was 550 ° C. (Example 44).

  In Example 42, the sheet resistance value after thermal treatment was 9.0Ω / □, the total light transmittance was 81.2%, and the haze ratio was 18.1%. In Example 43, the sheet resistance value after heat treatment was 8.7 Ω / □, the total light transmittance was 81.1%, and the haze ratio was 18.9%. In Example 44, the sheet resistance value after heat treatment was 8.4Ω / □, the total light transmittance was 81.0%, and the haze ratio was 19.8%. In Examples 42 to 44, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Example 45)
In Example 45, the surface electrode manufactured on the glass substrate in the same procedure as in Example 41 was subjected to heat treatment in the same manner as in Example 41 except that the degree of vacuum in the vacuum chamber was 1 × 10 ⁻⁶ Pa. went.

  In Example 45, the sheet resistance value after heat treatment was 7.9Ω / □, the total light transmittance was 80.9%, and the haze ratio was 20.6%. In Example 45, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Examples 46 to 48)
In Examples 46 to 48, the temperature at the time of heat-treating the surface electrode manufactured on the glass substrate in the same procedure as Example 41 in the vacuum chamber was 350 ° C. (Example 46), 450 ° C. (Example 47). A heat treatment was performed in the same manner as in Example 45 except that the temperature was 550 ° C. (Example 48).

  In Example 46, the sheet resistance value after heat treatment was 7.8Ω / □, the total light transmittance was 80.9%, and the haze ratio was 21.7%. In Example 47, the sheet resistance value after heat treatment was 7.1 Ω / □, the total light transmittance was 80.7%, and the haze ratio was 20.6%. In Example 48, the sheet resistance value after heat treatment was 6.9Ω / □, the total light transmittance was 80.6%, and the haze ratio was 23.7%. In Examples 46 to 48, the sheet resistance and the haze ratio improved, and the total light transmittance hardly changed before and after the heat treatment.

(Comparative Example 41)
In Comparative Example 41, except that the degree of vacuum in the vacuum chamber was set to 1 × 10 ⁻² Pa when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 41, Similarly, heat treatment was performed.

  In Comparative Example 41, the sheet resistance value after heat treatment was 11.0Ω / □, the total light transmittance was 81.4%, and the haze ratio was 14.8%. In Comparative Example 41, the effect of improving sheet resistance and haze ratio was not observed.

(Comparative Examples 42-44)
In Comparative Examples 42 to 44, the temperatures at which the surface electrodes manufactured on the glass substrate in the same procedure as in Example 41 were heat-treated in the vacuum chamber were 350 ° C. (Comparative Example 42) and 450 ° C. (Comparative Example 43). Heat treatment was performed in the same manner as in Comparative Example 41 except that the temperature was 550 ° C. (Comparative Example 44).

  In Comparative Example 42, the sheet resistance value after the heat treatment was 10.3Ω / □, the total light transmittance was 81.2%, and the haze ratio was 15.4%. In Comparative Example 43, the sheet resistance value after the heat treatment was 10.2 Ω / □, the total light transmittance was 81.2%, and the haze ratio was 14.3%. In Comparative Example 44, the sheet resistance value after the heat treatment was 10.4Ω / □, the total light transmittance was 81.1%, and the haze ratio was 16.9%. In Comparative Examples 42 to 44, the sheet resistance and the haze ratio were not improved.

(Comparative Examples 45 and 46)
In Comparative Examples 45 and 46, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 41 in the vacuum chamber was 200 ° C. (Comparative Example 45) and 600 ° C. (Comparative Example 46). A heat treatment was performed in the same manner as in Example 41 except that.

  In Comparative Example 45, the sheet resistance value after the heat treatment was 12.1Ω / □, the total light transmittance was 81.9%, and the haze ratio was 15.2%. In Comparative Example 46, the sheet resistance value after heat treatment was 26.7Ω / □, the total light transmittance was 81.7%, and the haze ratio was 14.2%. In Comparative Examples 45 and 46, the sheet resistance and the haze ratio were not improved.

(Comparative Examples 47 and 48)
In Comparative Examples 47 and 48, the temperature when heat treating the surface electrode manufactured on the glass substrate in the same procedure as in Example 41 in the vacuum chamber was 200 ° C. (Comparative Example 47) and 600 ° C. (Comparative Example 48). A heat treatment was performed in the same manner as in Example 45 except that.

  In Comparative Example 47, the sheet resistance value after heat treatment was 11.8Ω / □, the total light transmittance was 81.5%, and the haze ratio was 15.9%. In Comparative Example 47, the effect of improving sheet resistance and haze ratio was not observed.

  In Comparative Example 48, the sheet resistance value after heat treatment was 16.3 Ω / □, the total light transmittance was 81.3%, and the haze ratio was 21.2%. In Comparative Example 48, the effect of improving sheet resistance was not observed.

As shown in Tables 1 to 6, in Examples 1 to 48, the transparent conductive substrate with a surface electrode was subjected to heat treatment at 250 to 550 ° C. at a vacuum degree of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa. The sheet resistance and haze ratio could be improved. Moreover, in Examples 1-48, the haze rate was able to be improved 1.25 times or more before and after heat processing. Further, the transparency of the surface electrodes (transparent conductive film) obtained in Examples 1 to 48 was slightly reduced, but it was confirmed that it was within a range that had no practical problems.

On the other hand, in Comparative Examples 1 to 48, since the degree of vacuum at the time of heat treatment was less than 7 × 10 ⁻³ Pa or more than 1 × 10 ⁻⁶ Pa, the surface resistance and the haze ratio were not improved. Moreover, in Comparative Examples 1-48, since the heat processing temperature was less than 250 degreeC or exceeded 550 degreeC, sheet resistance and the haze rate were not able to be improved.

DESCRIPTION OF SYMBOLS 1 Translucent glass substrate, 2 surface electrode, 2a surface uneven structure, 21 base film, 22 uneven film, 3 photoelectric conversion semiconductor layer, 11 transparent conductive substrate with surface electrode, 31 p-type semiconductor layer, 32 i-type semiconductor layer, 33 n-type semiconductor layer, 4 back electrode, 41 transparent conductive oxide, 42 light reflective metal electrode

Claims (4)

A transparent substrate on which an indium oxide-based transparent conductive film is formed is set to 300 ° C. or higher, and an uneven structure is formed on the surface by sputtering on the transparent conductive film in an environment with a gas pressure of 1 to 10 Pa. A transparent conductive substrate with a surface electrode on which a surface electrode having a zinc oxide-based crystalline transparent conductive film is formed is heat-treated at 250 to 550 ° C. at a vacuum degree of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa. The manufacturing method of the transparent conductive substrate with a surface electrode characterized by performing. The zinc oxide crystalline transparent conductive film having a concavo-convex structure formed on the surface is doped with at least one selected from Al, Ga, B, In, F, Si, Ge, Ti, Zr, and Hf. claim 1 Symbol placement method for producing a transparent conductive substrate with a surface electrode, characterized in that it consists of. 3. The method for producing a transparent conductive substrate with a surface electrode according to claim 1, wherein the indium oxide-based transparent conductive film is made of indium oxide doped with at least one selected from Ti, Sn, and Ga. In the method for manufacturing a thin-film solar cell, in which a front electrode, a photoelectric conversion semiconductor layer, and a back electrode are sequentially formed on a translucent substrate
A transparent substrate on which an indium oxide-based transparent conductive film is formed is set to 300 ° C. or higher, and an uneven structure is formed on the surface by sputtering on the transparent conductive film in an environment with a gas pressure of 1 to 10 Pa. A transparent conductive substrate with a surface electrode on which the surface electrode having a zinc oxide-based crystalline transparent conductive film is formed is heat-treated at a vacuum degree of 7 × 10 ⁻³ to 1 × 10 ⁻⁶ Pa at 250 to 550 ° C. A method for producing a thin-film solar cell, comprising:

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