JPH09321326A - Manufacturing cis thin film solar cell and forming copper-indium-selenium alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the photoelectric conversion efficiency avoiding peel of a CIS layer of a solar cell by forming a Se layer or Se-containing layer adjacent to a conductive layer by plating. SOLUTION: A Cr layer 2 and Mo (conductive) layer thereon are sputtered on a soda lime glass 1 to form a substrate, and Se or Se-containing layer 4 is formed thereon by plating pref. electroplating to make a more smooth surface of the Se layer 4. For forming a Se or Se alloy layer by electroplating, a plating bath contg. a selenium dioxide water soln. (selenious) acid with sulfuric acid is pref. A brightener such as sodium citrate is pref. added to further reduce the uneven thickness.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to copper-indium-
The present invention relates to a method for manufacturing a CIS thin film solar cell having a selenium ternary alloy layer as an absorption layer.

[0002]

2. Description of the Related Art A solar cell is a device for converting light energy into electric energy, and is constructed by sequentially laminating an absorbing layer made of a photoelectric conversion semiconductor and a light transmitting electrode layer on a conductive substrate. Is normal. In such a photoelectric conversion semiconductor layer (absorption layer), the abundance ratio of atoms is 1: 1:
2 copper-indium-selenium ternary alloy (CuInS
It is considered that a thin film of e ₂ , hereinafter also referred to as “CIS”) exhibits the best photoelectric conversion efficiency.

One of the methods for producing this ternary alloy is Japanese Unexamined Patent Publication
It is proposed by Japanese Patent Laid-Open No. 1-237476. In this method, copper and indium are sequentially electrodeposited on a conductive substrate to form a precursor, and then heat treatment is performed while flowing an inert gas containing hydrogen selenide, and a copper-indium-selenium ternary alloy ( It was a method of forming a CuInSe ₂ ) layer.

Although a conductive substrate made of titanium or platinum is also used here, a molybdenum plate or a substrate having a molybdenum layer is mainly used.
This is because the coefficient of thermal expansion and the lattice coefficient are close to CIS.
This is because it is considered that the adhesion with the S layer is good. Here, C of the conventional CIS thin film solar cell
A method of forming the IS layer will be described with reference to FIG.

That is, as shown in FIG. 4A, a molybdenum layer B, a copper layer C, an indium layer D, and a selenium layer E are formed in this order on a soda lime glass A to be a substrate by sputtering or the like. Then, the laminate is heat-treated in the presence of hydrogen selenide to obtain a CIS layer (see FIG. 4 (b)).

Although it was expected that the CIS layer and the molybdenum layer have good adhesion as described above, in reality, the CIS layer formed in this way is easily peeled off, and as a result, is easily dropped off. Here, upon detailed investigation, it was found that molybdenum selenide (chemical formula: Mo _x Se _y , x and y are natural numbers) is formed between the molybdenum layer and the CIS layer of the substrate. FIG. 5 shows the results of examining the distribution of copper, indium, selenium, and molybdenum in the depth direction of the cross section of the one formed by the above-mentioned conventional technique by an energy dispersive X-ray analyzer. From FIG. 5, it is confirmed that the molybdenum selenide layer is formed between the CIS layer and the molybdenum layer.

It has been found that this molybdenum selenide has a layered structure and therefore causes the CIS layer formed on the molybdenum selenide layer to peel off from the substrate. That is, the molybdenum layer which is a conductive layer and the CIS
C when a molybdenum selenide layer is formed between the layers
FIG. 6 shows the result of examining the influence of the thickness of the molybdenum selenide layer (measured by a scanning electron microscope and an energy dispersive X-ray analyzer) on the adhesion of the IS layer. Here, the peeling occurrence rate is the ratio of the peeled area to the stuck area when a commercially available adhesive tape (Sumitomo 3M Mending Tape) is stuck and peeled.

From FIG. 6, it can be seen that the peeling occurrence rate increases as the thickness of the molybdenum selenide layer increases. If the CIS layer is easily peeled off, the handling efficiency is poor and the manufacturing yield is low, resulting in high cost, and a CIS solar cell with good performance cannot be obtained, and the obtained CIS solar cell also has poor durability. Will be things. Where C like this
As a technique for preventing peeling of the IS layer, Japanese Patent Application Laid-Open No. 6-
Japanese Patent No. 188444 proposes a technique of disposing a layer containing selenium in contact with a molybdenum layer. This one is
It is considered that during heat treatment for forming the copper-indium-selenium ternary alloy layer, a seed crystal of the copper-indium-selenium ternary alloy crystal is generated around the contact with the molybdenum layer, and the seed crystal develops in the surface direction. Therefore, it was considered that extremely excellent crystallinity and orientation were obtained, and as a result, an excellent solar cell with high efficiency was obtained. However, actually, although the solar cell obtained by the technique described in Japanese Patent Laid-Open No. 6-188444 has an effect of preventing peeling / falling off of CIS, its performance is not satisfactory.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, that is, a solar cell capable of obtaining a solar cell excellent in photoelectric conversion efficiency while preventing peeling of the CIS layer. It is intended to provide a manufacturing method.

[0010]

[Means for Solving the Problems] Japanese Patent Application Laid-Open No. 6-1884
As a result of various studies on the technique described in JP-A-44, it was found that fine unevenness was formed on the surface of the selenium layer formed on the molybdenum layer. Table 1 shows the results of examining the roughness of the surface of this selenium layer (thickness: 15 nm) using a stylus type surface profile measuring device. The surface roughness of the molybdenum layer (formed on the surface of soda lime glass) before forming the selenium layer is also described.

[0011]

[Table 1]

The roughness of the surface of the selenium layer as shown in Table 1 causes fine component unevenness during the formation of the copper-indium-selenium ternary alloy and hinders the growth of the seed crystal of CIS generated near the selenium layer. , And thought that the orientation was insufficient. Therefore, it was considered that a solar cell with high photoelectric conversion efficiency could be obtained by eliminating the roughness of the surface of the selenium layer, and the present invention was accomplished. That is, the present invention, in order to solve the above problems of the prior art, as described in claim 1, the production of a CIS thin film solar cell having a step of disposing a selenium layer or a layer containing selenium in contact with a conductive layer. In the method, the selenium layer or the layer containing selenium is formed by a plating method. By forming the selenium layer or the layer containing selenium by the plating method as described above, a CIS thin film solar cell having a high photoelectric conversion efficiency which cannot be obtained by a vacuum application technique such as vapor deposition as in the prior art is obtained. Since this solar cell can be obtained, and the peel strength of the CIS layer is high, it can be easily handled in the production process, and can be produced at high yield and low cost.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the selenium layer means a layer made of selenium, and the layer containing selenium means
It refers to a layer containing a selenium compound such as a selenium alloy layer or a selenium-dispersed plating layer, or selenium alone. In addition, in the present invention, plating refers to normal electroplating, electroless plating, and wet plating such as adsorbing colloidal particles to form a thin film (hereinafter referred to as “colloidal plating”).

Here, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a model diagram showing a method for manufacturing a CIS solar cell according to the present invention. In this figure, soda lime glass 1 is used as a substrate, and molybdenum layer 3 is formed as a conductive layer on chrome layer 2 formed on it. However, it is made of molybdenum (example: molybdenum plate) itself. Alternatively, a molybdenum layer formed on a chromium plate (chrome plate) may be used. Note that soda lime glass is used because of less peeling of the formed CIS layer in the heat treatment for forming the CIS layer, which will be described later, due to the thermal expansion coefficient.

First, as shown in FIG. 1A, a chromium layer 2 and a molybdenum layer 3 (conductive layer) formed on the chromium layer 2 are formed by sputtering, soda lime glass 1 is used as a substrate on the molybdenum layer 3. A selenium layer or a layer containing selenium is formed by plating as shown in FIG. Note that FIG. 1 shows an example in which a selenium layer is used among selenium layers or layers containing selenium, and this selenium layer is indicated by reference numeral 4. As described above, the plating for forming the selenium layer or the layer containing selenium is chemical plating,
Either electroplating or colloidal plating may be used, but it is necessary to determine conditions so as to reduce thickness unevenness. Here, electroplating is preferable because a selenium layer having a smoother surface can be obtained. When a layer made of selenium alone or a selenium alloy is formed by electroplating, plating from a plating bath containing an aqueous solution of selenium dioxide (selenic acid) under sulfuric acid acidity is preferable. In this case, it is preferable to add a brightening agent such as trisodium citrate because the uneven thickness can be further reduced. In addition, powdered selenium or copper or indium using a plating bath containing colloidal selenium dispersed therein,
Further, dispersion plating may be performed with copper and indium. In addition, by combining these, for example, powdery or colloidal selenium may be dispersed in a selenium plating bath for plating. Examples of the material plated with selenium include indium and copper. These may be plated alone or simultaneously with selenium on the conductive layer to form a layer containing selenium.

In the above plating, it is desirable to determine the conditions so that the thickness of the selenium layer or the layer containing selenium is 50 nm or more and 1 μm or less. That is, if the thickness of this layer is less than 50 nm, the effect of the present invention tends to be insufficient, while if it is more than 1 μm, excess selenium evaporates during the heat treatment described below, resulting in voids. It may cause peeling and cracking. On the selenium layer or the layer containing selenium thus formed, a copper layer and an indium layer are formed in this order or vice versa, or a copper indium layer is formed by means such as plating or sputtering. At this time, if selenium powder or fine particles of selenium are dispersed in this layer (or at least one layer in the case of two layers of a copper layer and an indium layer), good CIS without cracks or peeling is obtained.
Layers can be obtained. Here, the selenium fine particles can be obtained from selenium colloid. Note that FIG. 1C shows an example in which the copper indium layer 5 is formed on the selenium layer 4. In the present invention, the copper indium layer is a layer electrodeposited by a plating process using a plating bath containing copper and indium. Incidentally, these copper layers,
Regarding the thickness of the indium layer or the copper indium layer, the thickness of the CIS layer generated by the heat treatment described later is 1 to 3 μm.
It is desirable to adjust to m in terms of photoelectric conversion efficiency of the CIS solar cell.

Next, these laminates are heat-treated in an atmosphere containing selenium to grow CIS crystals and obtain CIS layers (see FIG. 1 (d)). Here, examples of the atmosphere containing selenium include hydrogen selenide and an inert gas containing selenium vapor. However, since hydrogen selenide is extremely toxic, it is desirable to use selenium vapor. Selenium vapor can be obtained by simultaneously encapsulating solid selenium in a vessel for heat treating the precursor. On the other hand, the heat treatment can be performed at 350 to 500 ° C. 40 here
It is desirable to perform the heat treatment at a temperature of 0 ° C. or higher and 500 ° C. or lower, because a highly efficient solar cell can be obtained. The processing time is usually about 30 to 120 minutes. By this heat treatment, a seed crystal of a copper-indium-selenium ternary alloy crystal is generated around the molybdenum layer by selenium derived from the selenium layer or the layer containing selenium in contact with the conductive layer. At this time, since the selenium layer formed by plating or the layer containing selenium has less thickness unevenness,
This CIS seed crystal easily develops in the surface direction, so that a CIS layer having extremely excellent crystallinity and orientation can be obtained. Since CIS is crystallographically stable, it does not permeate selenium once it is formed, which prevents selenium from penetrating into the molybdenum layer from the vapor phase, and as a result suppresses the formation of molybdenum selenide.

Further, on the CIS layer thus formed, a cadmium sulfide (CdS) layer which is an n-type semiconductor,
A zinc selenide layer which is also an n-type semiconductor is formed by, for example, a vapor deposition method. For the formation of the n-type semiconductor CdS layer, a solution growth (CBS) method may be applied other than the above vapor deposition method. The thickness of the CdS layer is 0.02-0.3μ
It is desirable that it is m. CdS layer thickness is 0.02μ
If it is less than m, the coverage of CIS with CdS will be incomplete, and if it exceeds 0.3 μm, the light transmittance of the CdS layer will be low, and thus the photoelectric conversion efficiency tends to decrease.

Finally, as the window layer, a zinc oxide (ZnO) layer doped with aluminum for improving conductivity is formed by sputtering to complete a thin film solar cell (see FIG. 1 (e)). Here, the thickness of the ZnO layer is preferably 0.5 to 2 μm. If the thickness of the ZnO layer is less than 0.5 μm, the loss increases due to an increase in series resistance, and if it exceeds 2 μm, the light transmittance decreases and the efficiency tends to decrease, which also causes a cost increase. The thin film solar cell thus obtained is then provided with an antireflection film or the like if necessary, and a lead wire or the like is connected to this layer and the conductive substrate for use.

[0020]

【Example】

Example 1 and Comparative Example <Formation of Conductive Layer> Chromium was deposited on a soda-lime glass having a thickness of 1 mm by sputtering to a thickness of 0.2 μm, and molybdenum was deposited on the chromium layer to a thickness of 2.0 μm. did. The center line average roughness of the surface of the molybdenum layer was measured by a stylus type surface shape measuring device and found to be 0.7.
was nm. <Formation of selenium-containing copper indium layer in contact with conductive layer>
Furthermore, on this molybdenum thin film, copper sulfate (CuSO ₄ )
10 mmol / l, indium sulfate (In ₂ (S
O ₄ ) ₃ ) 50 mmol / l, selenium dioxide (SeO ₂ )
10 mmol / l, trisodium citrate 50 mmol
/ L and sulfuric acid 500 mmol / l in a plating bath prepared by dissolving in water, using a platinum plate as a counter electrode and a mercuric sulfate electrode as a reference electrode, respectively, with respect to the mercuric sulfate electrode. Electroplating was carried out for 2 minutes so as to have a constant potential of -1.0 V to form a copper indium layer (thickness: 50 nm) containing selenium. When the center line average roughness of the surface of the copper indium layer containing selenium was measured, 2.
6 nm.

<Formation of CIS Layer> On the copper indium layer containing selenium thus formed, copper sulfate (Cu
SO ₄ ) 0.2 mol / l, sodium sulfate (Na ₂ S
In a copper plating bath prepared by dissolving O ₄ ) in water to a concentration of 0.1 mol / l, using a copper plate as a counter electrode, a current density of 30 m
A copper layer was formed by plating at A / cm ² for 2 minutes by a constant current method. Further, on the copper layer, indium sulfate (In ₂ (SO ₄ ) 50 mmol / l, sodium sulfate (Na ₂ SO ₄ ) 80 mmol / l, and trisodium citrate 25 mmol / l were dissolved in water so as to be. The indium plating bath was prepared by using a platinum electrode as a counter electrode and plating was performed by a constant current method at a current density of 10 mA / cm ² for 2.5 minutes to form an indium layer. When the composition analysis of the laminated film including the copper layer and the indium layer was performed using the fluorescent X-ray analyzer, the abundance ratios of the copper atom, the indium atom, and the selenium atom were 37, 41, and 22, respectively. When such a laminated film was subjected to heat treatment at 500 ° C. for 60 minutes in nitrogen together with selenium powder, the composition of the obtained layer was analyzed. Abundance of Kooyobi selenium atom respectively 23,25,52, copper - indium -
It was found to be close to the stoichiometric composition of the selenium ternary alloy. The obtained CIS layer (thickness: 2 μ
m) was good without peeling or cracking.

<Evaluation of CIS Layer> Further, when a commercially available adhesive tape (Mending Tape manufactured by Sumitomo 3M Ltd.) was attached to the CIS layer and the adhesive tape was peeled off, CI was obtained.
As to whether or not peeling occurred in the S layer, 5 samples prepared in the same manner were investigated (hereinafter, such a peeling evaluation method is referred to as a "tape test"), but only 1 sample peeled out of the 5 samples. It was found that the adhesion between the CIS layer formed by the method according to the present invention and the conductive layer was extremely good (Example 1). In addition, regarding the portion where the peeling did not occur in the sample,
The cross section was examined by an energy dispersive X-ray analyzer. The result is shown in FIG. From FIG. 2, it was confirmed that the CIS layer of Example 1 and the conductive layer (molybdenum layer) were in direct contact with each other, and a molybdenum selenide layer was not formed between these layers.

The CIS layer (the abundance ratios of the copper atom, the indium atom and the selenium atom are the same as those in the above-mentioned Example 1 except that the copper indium layer containing selenium in contact with the conductive layer is not formed. The same tape test was performed on 5 samples (Comparative Example 1) having 23, 25, and 52), and peeling occurred on 4 samples. In addition, the copper indium layer containing selenium was not separately formed by plating, and instead, a selenium layer (thickness: 15 nm) was formed in contact with the conductive layer by a vacuum deposition method, and the same procedure as in Example 1 was performed. 5 samples obtained (Comparative Example 2)
Also, when the tape test was conducted in the same manner, peeling occurred in two samples. The center line average roughness of the surface of the selenium layer formed by the above-mentioned sputtering method was measured and found to be 3.2 nm.

[Example 2] <Formation of selenium layer in contact with conductive layer> Similarly to Example 1, a chromium layer and a molybdenum layer were formed on the chromium layer by sputtering on a soda-lime glass having a thickness of 1 mm. The selenium layer (thickness: 100) is deposited on the selenium colloidal solution by immersing it on the selenium colloidal solution for 30 minutes.
nm). The selenium colloid solution used was prepared from the selenium colloid stock solution prepared by the following procedure so that the selenium concentration would be 10 mmol / l. That is, 4 ml of gelatin aqueous solution (4 g / l), 10 ml of selenous acid aqueous solution (0.1 mol / l), 10 ml of hydrazinium sulfate aqueous solution (0.1 mol / l), and 30 ml of water were mixed and heated at 40 ° C. for 45 minutes. , PH was adjusted to 2 to stabilize the colloid to obtain a selenium colloid stock solution. Here, gelatin is added to stabilize the colloid. When the colloidal particles of the selenium colloid stock solution thus prepared were examined by a scanning electron microscope, the particle size of the selenium colloidal particles was 10 nm or more and 100 n or more.
It was not more than m and was very stable without precipitation of selenium particles even when left for a long time.

The center line average roughness of the surface of the selenium layer formed as described above was measured and found to be 4.0 nm.
A copper layer and an indium layer were formed on this selenium layer by the electroplating method in the same manner as in Example 1. When the composition analysis of these laminated films (selenium layer, copper layer and indium layer) was carried out using a fluorescent X-ray analyzer, the abundance ratios of copper atoms, indium atoms and selenium atoms were 48, 45 and 7, respectively. It was

<Formation / Evaluation of CIS Layer> Such a laminated film was subjected to heat treatment in nitrogen together with selenium powder at 500 ° C. for 60 minutes, and the composition of the obtained layer was analyzed. The abundance ratios of atoms and selenium atoms were 24, 26, and 50, respectively. The obtained CIS layer (thickness: 2 μm) was a good one without peeling or cracking, and when a tape test was conducted, none of the five samples peeled. When the cross section of one of these samples was examined by an energy dispersive X-ray analyzer, it was confirmed that a molybdenum selenide layer was not formed between the CIS layer and the conductive layer.

[Example 3] <Formation of copper layer containing selenium in contact with conductive layer> As in Example 1, on a soda lime glass having a thickness of 1 mm, a chromium layer was formed on the chromium layer and the chromium layer by vacuum vapor deposition. A molybdenum layer is deposited on the molybdenum thin film, and copper sulfate (CuSO ₄ ) 10 mmol / l and selenium dioxide (Se) are deposited on the molybdenum thin film.
O ₂ ) 10 mmol / l, trisodium citrate 50 m
In a plating bath prepared by dissolving it in water so as to have mol / l and sulfuric acid of 500 mmol / l, a platinum plate was used as a counter electrode, and electroplating was carried out at a current density of 10 mA / cm ^{2 with} respect to the plated surface. After that, the copper layer containing selenium (thickness: 15 nm) was formed.

The center line average roughness of the surface of the copper layer containing selenium formed as described above was measured and found to be 2.6 nm. On the copper layer containing selenium, as in Example 1,
However, the treatment time was adjusted and the indium layer was formed by the electroplating method. When the composition analysis of these laminated films (copper layer containing selenium and indium layer) was performed using an X-ray fluorescence analyzer, the abundance ratios of copper atoms, indium atoms and selenium atoms were 23, 25 and 52, respectively. It was

<Formation / Evaluation of CIS Layer> Such a laminated film was heat treated in the same manner as in Example 1 and the composition of the obtained layer was analyzed. As a result, the abundance ratios of copper atoms, indium atoms and selenium atoms were found. Are 23, 25 and 52 respectively, and
The obtained CIS layer (thickness: 2 μm) was a good one without peeling or cracking, and when a tape test was conducted, only one sample out of five samples peeled,
No peeling occurred in the remaining 4 samples (Example 3). The cross-section of the peeled sample in the non-peeled sample was examined by an energy dispersive X-ray analyzer. As a result, a molybdenum selenide layer was formed between the CIS layer and the conductive layer. It was confirmed that there was not.

[Example 4] <Formation of indium layer containing selenium in contact with conductive layer> As in Example 1, on a soda lime glass having a thickness of 1 mm, a chromium layer was formed on the chromium layer and the chromium layer by sputtering. A molybdenum layer is deposited, and indium sulfate (In ₂ (SO ₄ ) ₃ ) 50 mmo is further deposited on this molybdenum thin film.
l / l, selenium colloid 10 mmol / l (using the selenium colloid stock solution used in Example 2), trisodium citrate 25 mmol / l, and sulfuric acid 500 mmol / l.
In a plating bath prepared by dissolving in water so as to obtain a platinum electrode as a counter electrode, plating was performed at a current density of 30 mA / cm ² for 2 minutes to form an indium layer containing selenium.

When the center line average roughness of the surface of the indium layer containing selenium formed as described above was measured, it was 50
was nm. A copper layer was formed on the indium layer containing selenium by the electroplating method in the same manner as in Example 1, except that the treatment time was adjusted. When the composition analysis of these laminated films (the indium layer containing selenium and the copper layer) was performed using a fluorescent X-ray analyzer, the abundance ratios of copper atoms, indium atoms and selenium atoms were 37, 41 and 22, respectively. It was

<Formation / Evaluation of CIS Layer> Such a laminated film was subjected to heat treatment in the same manner as in Example 1 and the composition of the obtained layer was analyzed. As a result, the abundance ratios of copper atoms, indium atoms and selenium atoms were found. Are 23, 25 and 52 respectively, and
The obtained CIS layer (thickness: 2 μm) was a good one without peeling or cracking, and when a tape test was conducted, peeling occurred in 2 out of 5 samples, but peeled in the remaining 3 samples. Did not occur (Example 4).
The cross-section of the peeled sample in the non-peeled sample was examined by an energy dispersive X-ray analyzer. As a result, a molybdenum selenide layer was formed between the CIS layer and the conductive layer. It was confirmed that there was not.

[Evaluation as Solar Cell] Examples 1 to 1 above
Among the samples obtained in Example 4, Comparative Example 1 and Comparative Example 2, those without obstacles such as peeling were selected, and these CISs were selected.
A cadmium sulfide layer was formed on each of the layers by liquid phase epitaxy. That is, 70 ° C cadmium sulfate (CdSO
₄ ) 0.01 mol / l aqueous solution (pH was adjusted to 8.
5) was soaked in the soda lam glass on which the above thin film layer was formed for 5 minutes, and then thiourea 0.01
A mol / l aqueous solution was added, and the mixture was kept for 5 minutes to grow a cadmium sulfide layer, thoroughly washed with water, and then dried under nitrogen.
The thickness of the obtained cadmium sulfide layer is 0.05 μm.
Met.

Thereafter, a 2 μm thick thin film of a zinc oxide layer doped with 2% by weight of aluminum was formed on each of these by sputtering to obtain thin film solar cells A to F. . In addition, among the obtained solar cells, the one using the sample of Comparative Example 1 (thin film solar cell E) had relatively large peeling and cracks in its peripheral portion. In addition, some of the samples using the sample of Comparative Example 2 (thin film solar cell F) also had cracks in the peripheral portion (1 sample out of 4 samples). On the other hand, such defects did not occur in the samples using the samples of Examples 1 to 4 (thin film solar cells A to D). The characteristics of a circular portion having a diameter of 2 mm at the center of each of the CIS thin-film solar cells A to D were measured using a solar cell output characteristic device (manufactured by WACOM).
Table 2 shows the results. In addition, solar cell A and solar cell E
And the IV curve of the solar cell F is shown in FIG.

[0035]

[Table 2]

From Table 2 and FIG. 3, the CIS according to the present invention is shown.
It can be seen that the output characteristics of the thin film solar cell are superior to those of the conventional solar cells E and F.

[0037]

EFFECTS OF THE INVENTION A seed crystal of a copper-indium-selenium ternary alloy crystal is formed in the periphery in contact with a molybdenum layer by selenium derived from a selenium layer in contact with the conductive layer or a layer containing selenium. This CIS seed crystal easily develops in the surface direction because the thickness unevenness of the formed selenium layer or the layer containing selenium is small, and as a result, very excellent crystallinity and orientation degree are obtained, and as a result, it is excellent. A CIS solar cell having photoelectric conversion efficiency can be obtained with high yield.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a manufacturing process of a CIS thin film solar cell according to the present invention.

FIG. 2 is a diagram showing a result of analysis in a depth direction by an energy dispersive X-ray analyzer in a cross section of a CIS layer and a molybdenum layer formed in Example 1.

FIG. 3 shows a solar cell A according to the present invention and a solar cell E as a comparative example.
It is a figure which shows the IV curve of F and F.

FIG. 4 is a diagram showing a method for forming a CIS layer according to a conventional technique.

FIG. 5 is a diagram showing an analysis result in a depth direction by an energy dispersive X-ray analysis device in a cross section of a CIS layer and a molybdenum layer formed by a conventional technique.

FIG. 6 is a graph showing the results of examining the effect of the thickness of the molybdenum selenide layer on the adhesion of the CIS layer.

[Explanation of symbols]

 1 Soda lime glass 2 Chromium layer 3 Molybdenum layer (conductive layer) 4 Selenium layer 5 Copper indium layer 6 CIS layer 7 Cadmium sulfide layer 8 Zinc oxide layer

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[Procedure amendment]

[Submission date] February 21, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

Further, on the CIS layer thus formed, a cadmium sulfide (CdS) layer which is an n-type semiconductor and a zinc selenide layer which is also an n-type semiconductor are formed by, for example, a vapor deposition method. Regarding the formation of the n-type semiconductor CdS layer, solution growth ( CBD (Chemical
al Bath Deposition) ) method may be applied. The thickness of the CdS layer is 0.02-0.3μ
It is desirable that it is m. CdS layer thickness is 0.02μ
If it is less than m, the coverage of CIS with CdS will be incomplete, and if it exceeds 0.3 μm, the light transmittance of the CdS layer will be low, and thus the photoelectric conversion efficiency tends to decrease.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Kamiya 1500, Onjuku, Susono, Shizuoka Prefecture, Yazaki Sogyo Co., Ltd. 1500 Onjuku, Susono-shi, Shizuoka Inside Yazaki Corporation

Claims (4)

[Claims] 1. A method for producing a CIS thin-film solar cell comprising a step of disposing a selenium layer or a layer containing selenium in contact with a conductive layer, wherein the selenium layer or the layer containing selenium is formed by a plating method. A method for manufacturing a CIS thin-film solar cell, which is characterized. 2. The method for producing a thin film solar cell according to claim 1, wherein the layer in contact with the conductive layer is either a copper layer containing selenium or an indium layer containing selenium. . 3. The layer in contact with the conductive layer is a layer made of copper, indium and selenium.
The method for producing a CIS thin-film solar cell according to 1. 4. When forming a copper-indium-selenium ternary alloy in contact with a conductive layer, selenium or a layer containing selenium is formed in contact with the conductive layer by a plating method, and then selenium or selenium is added. Forming at least one of a copper layer, an indium layer, or a copper indium layer on the layer, and then performing heat treatment in an atmosphere containing selenium, to form a ternary alloy of copper-indium-selenium.