JP2013058554A - Method for manufacturing stacked thin-film photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a high-performance stacked thin-film photoelectric conversion device, capable of enhancing flexibility and improving production efficiency in manufacturing processes.SOLUTION: A method for manufacturing a stacked thin-film photoelectric conversion device at least including an amorphous photoelectric conversion unit, an n-type silicon composite layer and a crystalline photoelectric conversion unit in order from a light incident side, includes the steps of: forming the amorphous photoelectric conversion unit; forming the n-type silicon composite layer; exposing the formed n-type silicon composite layer in the atmosphere; subjecting the n-type silicon composite layer subjected to the atmosphere exposure to atmospheric pressure plasma treatment when a mixed gas of a dilution gas composed of nitrogen or a rare gas, and an oxygen-contained vapor is introduced; and then forming a p-type semiconductor layer of the crystalline photoelectric conversion unit in a decompressed state. The method may include no step of further forming the n-type silicon composite layer after the step of subjecting the n-type silicon composite layer to the atmospheric pressure plasma treatment.

Description

  The present invention relates to a method for manufacturing a stacked thin film photoelectric conversion device, and relates to a manufacturing method that not only provides a high-performance photoelectric conversion device but also increases the flexibility of the manufacturing process and improves the production efficiency.

  Note that the terms “crystalline” and “microcrystal” in the present specification include those that partially contain amorphous material.

  In recent years, in order to achieve both cost reduction and high efficiency of a photoelectric conversion device, a thin film photoelectric conversion device that has almost no problem in terms of resources has attracted attention and has been vigorously developed. Thin film photoelectric conversion devices are expected to be applied to various applications such as solar cells, optical sensors, and displays. An amorphous silicon photoelectric conversion device, which is one of thin film photoelectric conversion devices, can be formed on a large-area glass substrate or stainless steel substrate at a low temperature, so that cost reduction can be expected.

  A multilayer thin film photoelectric conversion device generally includes a first electrode, a surface of which is sequentially laminated on an insulating substrate, one or more semiconductor thin film photoelectric conversion units, and a second electrode. One thin film photoelectric conversion unit includes an i-type layer sandwiched between a p-type layer and an n-type layer. Here, the photoelectric conversion unit or the thin-film solar cell has an amorphous i-type photoelectric conversion layer that occupies the main part regardless of whether the p-type and n-type conductivity type layers included therein are amorphous or crystalline. Those having a high quality are referred to as amorphous photoelectric conversion units or amorphous thin film solar cells, and those having a crystalline i-type layer are referred to as crystalline photoelectric conversion units or crystalline thin film solar cells.

As a method for improving the conversion efficiency of a stacked photoelectric conversion device, a photoelectric conversion device employing a so-called tandem structure in which two or more photoelectric conversion units are stacked is known. In this method, a front photoelectric conversion unit including a photoelectric conversion layer having a large band gap is disposed on the light incident side of the photoelectric conversion device, and a rear photoelectric conversion unit including a photoelectric conversion layer having a small band gap is sequentially arranged behind the photoelectric conversion layer. By arranging, photoelectric conversion can be performed over a wide wavelength range of incident light, thereby improving the conversion efficiency of the entire apparatus. (In the present application, a photoelectric conversion unit disposed relatively on the light incident side is referred to as a front photoelectric conversion unit, and a photoelectric conversion unit disposed adjacent to a side farther from the light incident side than this is referred to as a rear photoelectric conversion unit. Called a conversion unit.)
Furthermore, a stacked photoelectric conversion device having a structure in which both a light transmitting property and a light reflecting property are interposed between a plurality of stacked photoelectric conversion units and a conductive intermediate reflective layer is interposed has recently been proposed. . In this case, a part of the light reaching the intermediate reflection layer is reflected, and the amount of light absorption in the front photoelectric conversion unit located on the light incident side of the intermediate reflection layer is increased, and is generated in the front photoelectric conversion unit. The current value can be increased. For example, when an intermediate reflective layer is inserted into a hybrid photoelectric conversion device composed of an amorphous silicon photoelectric conversion unit and a crystalline silicon photoelectric conversion unit, the amorphous silicon photoelectric conversion is performed without increasing the film thickness of the amorphous silicon layer. The current generated by the unit can be increased. Alternatively, the amorphous silicon photoelectric conversion unit due to photodegradation that becomes conspicuous as the thickness of the amorphous silicon layer increases because the thickness of the amorphous silicon layer necessary to obtain the same current value can be reduced. It is possible to suppress the deterioration of characteristics.

  By the way, since the stacked photoelectric conversion device has a large number and types of semiconductor layers, a large-scale facility is required to continuously form a plurality of units with a single plasma CVD device. In other ways, such as when facilities are relocated, it becomes inflexible. In addition, particularly in the case of an in-line type plasma CVD apparatus, there is a risk that the operating rate decreases as the equipment becomes larger. Also, for example, the front photoelectric conversion unit represented by an amorphous silicon-based unit and the rear photoelectric conversion unit represented by a crystalline silicon-based unit differ in the time required for film formation due to a difference in film thickness, etc. Furthermore, the optimum formation conditions and the optimum plasma CVD apparatus configuration are also different. However, when these are used in separate plasma CVD apparatuses, such concerns are reduced, and the flexibility and production efficiency of the manufacturing process can be improved. For example, a front photoelectric conversion unit is formed on a substrate using a plasma CVD apparatus, the substrate is once taken out from the plasma CVD apparatus into the atmosphere, and then transferred to another plasma CVD apparatus to continuously form a rear photoelectric conversion unit. There is a manufacturing method.

(Prior Example 1)
In Patent Document 1, as viewed from the light incident side, a photoelectric layer formed by a plasma C V D method is disposed in the order of one conductivity type layer, a substantially intrinsic semiconductor photoelectric conversion layer, and a reverse conductivity type layer. A method for manufacturing a stacked photoelectric conversion device including a plurality of conversion units, wherein a reverse conductivity type layer in a front photoelectric conversion unit disposed relatively on a light incident side and a rear side of the front photoelectric conversion unit are adjacent to each other. One or both of the conductivity type layers in the rear photoelectric conversion unit arranged in a manner are provided with a conductivity type layer having at least a part of a silicon composite layer in which a silicon crystal phase is mixed in an amorphous alloy of silicon and oxygen. And forming the silicon composite layer up to a part of the silicon composite layer, and then taking it out to the atmosphere, so that the outermost surface of the silicon composite layer is exposed to the air, and then the remaining of the same conductivity type. Silicon Characterized by having a step of forming a coupling layer, the manufacturing method of the stacked photoelectric conversion device is disclosed.

JP-A-2005-277303

  After the formation of up to a part of the silicon composite layer as described in Patent Document 1 described above, the outermost surface of the silicon composite layer is exposed to the atmosphere once, and then the same conductivity type. By forming the remaining silicon composite layer, deterioration of performance due to atmospheric exposure is suppressed and characteristics are improved. However, in order to form the same silicon composite layer with a plurality of CVD apparatuses, it is necessary to have CVD apparatuses having the same gas line. Therefore, in order to increase the flexibility of the manufacturing process, it is desirable to expose to the atmosphere before or after the formation of the silicon composite layer, but there is a problem that the performance deteriorates if taken out to the atmosphere before or after the formation of the silicon composite layer. .

  Therefore, an object of the present invention is to provide a manufacturing method capable of improving production efficiency by improving flexibility of a manufacturing process of a laminated thin film solar cell and improving photoelectric conversion characteristics.

The first of the present invention is “a method for producing a laminated thin film photoelectric conversion device including at least an amorphous photoelectric conversion unit, an n-type silicon composite layer, and a crystalline photoelectric conversion unit in order from the light incident side,
The photoelectric conversion unit includes, in order from the light incident side, one conductivity type layer, a substantially intrinsic semiconductor photoelectric conversion layer, and a reverse conductivity type layer. The one conductivity type layer is a p-type layer, and the reverse conductivity type. The layer is an n-type layer, and the n-type silicon composite layer is an n-type layer in which a silicon crystal phase is mixed in an amorphous alloy of silicon and oxygen,
Forming an amorphous photoelectric conversion unit;
forming an n-type silicon composite layer;
Exposing the formed n-type silicon composite layer to the atmosphere;
A step of performing atmospheric pressure plasma treatment on the n-type silicon composite layer exposed to the atmosphere in a state where a mixed gas of a dilution gas composed of nitrogen or a rare gas and an oxygen-containing vapor is introduced;
And a step of forming a p-type semiconductor layer of the crystalline photoelectric conversion unit under reduced pressure, and a method for producing a laminated thin-film photoelectric conversion device ”.

  The present invention is also characterized in that “the step of further forming the n-type silicon composite layer is not provided between the step of performing the atmospheric pressure plasma treatment and the step of forming the p-type semiconductor layer. Manufacturing method of the laminated thin-film photoelectric conversion device.

  The present invention is also “a method for producing the laminated thin film photoelectric conversion device, wherein the dilution gas is nitrogen and the oxygen-containing vapor is oxygen or dry air”.

  The present invention is also “a method for producing the laminated thin film photoelectric conversion device, wherein a flow ratio of oxygen to nitrogen in the mixed gas is 10 ppm or more and 300 ppm or less”.

  The present invention is also characterized in that "atmospheric pressure plasma treatment conditions are selected such that a water contact angle on the surface of the n-type silicon composite layer is 10 ° or less for one hour after the step of performing the atmospheric pressure plasma treatment. The manufacturing method of the laminated thin film photoelectric conversion device described above.

  According to the present invention, the following specific effects can be obtained. That is, since an n-type silicon composite layer characterized by containing a silicon crystal phase in an amorphous alloy of silicon and oxygen is used as an intermediate transmission reflection layer, light is partially reflected at the front and back interfaces of the silicon composite layer. The power generation current of the front photoelectric conversion unit can be increased, or the i-type layer of the front photoelectric conversion unit can be thinned to generate an equivalent power generation current. Characteristics can be improved.

  In addition, a laminated photoelectric conversion device having a large number of silicon-based thin films and photoelectric conversion units is formed by using a single plasma CVD apparatus without forming the same film by using a plurality of CVD apparatuses. Thus, it is possible to provide a manufacturing method that can increase the flexibility and improve the production efficiency.

  A feature of the present invention is that after the n-type silicon composite layer is formed, it is exposed to the atmosphere and treated with atmospheric pressure plasma into which a mixed gas of oxygen-containing vapor and nitrogen or a rare gas is introduced. Is effective in removing excess dopant atoms remaining in a conductive layer such as an n-type silicon composite layer.

  Due to the effects as described above, according to the present invention, a high-performance and low-cost stacked photoelectric conversion device can be provided.

Note that surface modification by atmospheric pressure plasma treatment using a mixed gas containing oxygen-containing vapor is well known as disclosed in, for example, JP-A-10-154598. However, the object is applied to a resin film, glass, and metal, and is not generally used for a semiconductor layer. This is because, when an atmospheric pressure plasma treatment using a mixed gas containing oxygen-containing vapor is performed on the semiconductor layer, the surface is oxidized to form an insulator, which increases resistance and impairs semiconductor characteristics. This is because it is assumed easily. Therefore, there are obstacles to the atmospheric pressure plasma treatment on the semiconductor layer, and those skilled in the art cannot easily conceive.
However, in the present invention, a remarkable effect is manifested by overcoming this obstruction factor and deliberately selecting atmospheric pressure plasma treatment.

Cross-sectional view of a multilayer thin film photoelectric conversion device according to an embodiment of the present invention Water contact angle before and after atmospheric pressure plasma treatment

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each drawing of the present application, dimensional relationships such as thickness and length are appropriately changed for clarity and simplification of the drawings, and do not represent actual dimensional relationships. Moreover, in each figure, the same referential mark represents the same part or an equivalent part.

  Forming a stacked photoelectric conversion device having a large number of silicon-based thin films and photoelectric conversion units with a plurality of plasma CVD devices is important in terms of increasing the flexibility of the manufacturing process and improving the production efficiency. However, since it is formed by a plurality of plasma CVD apparatuses, there is a problem that if the atmosphere is exposed during the film formation, the characteristics deteriorate due to the influence of adhesion of impurities. Taking out the silicon composite layer to the atmosphere in the middle of film formation, the outermost surface of the silicon composite layer is exposed to the air, and then forming the remaining silicon composite layer of the same conductivity type, so that the deterioration of performance due to atmospheric exposure is suppressed. Improved characteristics. However, in order to form the same silicon composite layer with a plurality of CVD apparatuses, it is necessary to have CVD apparatuses having the same gas line. Therefore, the application of the process using the atmospheric pressure plasma treatment was studied earnestly.

  Surface modification by atmospheric pressure plasma treatment using a mixed gas containing oxygen-containing vapor is well known as shown in, for example, JP-A-10-154598. However, the object is applied to a resin film, glass, or metal, and is not generally used for a semiconductor layer. This is because, when an atmospheric pressure plasma treatment using a mixed gas containing oxygen-containing vapor is performed on the semiconductor layer, the surface is oxidized to form an insulator, which increases resistance and impairs semiconductor characteristics. This is because it is assumed easily.

  However, the inventor made an n-type silicon composite layer after exposure to the air by performing atmospheric pressure plasma treatment using a mixed gas containing oxygen-containing vapor after the n-type silicon composite layer was formed. The present inventors have found a manufacturing method in which the p-type semiconductor layer of the crystalline photoelectric conversion unit is formed in a reduced pressure state without forming a film, so that it can be exposed to the atmosphere without degrading characteristics. By treating the n-type silicon composite layer with atmospheric pressure plasma using a mixed gas containing oxygen-containing vapor, it is considered that the characteristics were improved because excess dopant atoms contained in the n-type silicon composite layer were removed. In the course of the study, it was found that the characteristics of the laminated thin film photoelectric conversion device were lowered when exposed to the atmosphere before the n-type silicon composite layer was formed and treated with atmospheric pressure plasma. It was found that it was important to perform atmospheric pressure plasma treatment after exposure to the atmosphere. This is presumably because the n-type silicon composite layer was originally an oxygen-containing layer and was not oxidized by the atmospheric pressure plasma treatment.

  FIG. 1 is a cross-sectional view of a stacked thin film photoelectric conversion device according to an example of an embodiment of the present invention. A transparent electrode layer 2, a front photoelectric conversion unit 3, an intermediate transmission / reflection layer 4, and a rear photoelectric conversion unit 5 are sequentially formed on the transparent insulating substrate 1. A back electrode layer 5 composed of a back transparent electrode layer 51 and a back metal electrode layer 52 is disposed to form a stacked thin film photoelectric conversion device.

  A plate-like member or a sheet-like member made of glass, transparent resin or the like is used for the transparent substrate 1 used in a photoelectric conversion device of a type in which light enters from the substrate side. In particular, it is preferable to use a glass plate as the transparent substrate 1 because it has a high transmittance and is inexpensive.

  That is, since the transparent substrate 1 is located on the light incident side of the thin film photoelectric conversion device, it is preferable that the transparent substrate 1 be as transparent as possible so that more sunlight is transmitted and absorbed by the photoelectric conversion unit. From the same intention, it is preferable to provide a non-reflective coating on the light incident surface of the transparent substrate 1 in order to reduce the light reflection loss on the sunlight incident surface.

The transparent electrode layer 2 is preferably made of a conductive metal oxide such as SnO ₂ or ZnO, and is preferably formed using a method such as CVD, sputtering, or vapor deposition. The transparent electrode layer 2 desirably has the effect of increasing the scattering of incident light by having fine irregularities on its surface.

  The semiconductor layer includes one or more photoelectric conversion units. If an amorphous silicon-based material is selected as the front photoelectric conversion unit 3, it has sensitivity to light of about 360 to 800 nm, and if a crystalline silicon-based material is selected for the rear photoelectric conversion unit 5, it is longer than about 1200 nm. Sensitivity to light. Therefore, the thin-film photoelectric conversion device arranged in this order from the light incident side to the front photoelectric conversion unit 3 of the amorphous silicon-based material and the rear photoelectric conversion unit 5 of the crystalline silicon-based material is effective in a wider range. Be available. However, “silicon-based” materials include silicon alloy semiconductor materials containing silicon such as silicon carbide and silicon germanium in addition to silicon.

  In addition to the method of laminating a plurality of thin film photoelectric conversion units as described above, the conversion efficiency of the thin film photoelectric conversion device can be improved by using a conductive material between the thin film photoelectric conversion units rather than the material forming the thin film photoelectric conversion unit. There is a method of forming the intermediate transmission / reflection layer 4 made of a material having a low refractive index. By having such an intermediate transmission reflection layer 4, it is possible to design to reflect light on the short wavelength side and transmit light on the long wavelength side, and more effectively perform photoelectric conversion in each thin film photoelectric conversion unit. Become.

  For example, when an intermediate transmission / reflection layer is inserted into a hybrid thin film photoelectric conversion device composed of a front amorphous silicon photoelectric conversion unit and a rear crystalline silicon photoelectric conversion unit, the thickness of the amorphous silicon photoelectric conversion layer is increased. Without increasing the current generated by the front photoelectric conversion unit. In addition, when the intermediate transmission / reflection layer is included, the amorphous silicon photoelectric conversion layer necessary for obtaining the same current value can be made thinner than when the intermediate transmission / reflection layer is not included. It becomes possible to suppress the deterioration of the characteristics of the amorphous silicon photoelectric conversion unit due to the photodegradation (Staebler-Wronsky effect) that becomes conspicuous as the thickness of the porous silicon layer increases.

  The intermediate transmission / reflection layer may be inserted between the front photoelectric conversion unit and the rear photoelectric conversion unit, but the intermediate transmission / reflection layer may be provided on a part of the reverse conductivity type layer of the front photoelectric conversion unit.

  The front photoelectric conversion unit 3 is formed, for example, by stacking semiconductor layers by plasma CVD in the order of pin layers. Specifically, for example, a p-type amorphous silicon carbide layer doped with 0.01 atomic% or more of boron, which is a conductivity type determining impurity atom, is used as one conductivity type layer 31, and an intrinsic amorphous silicon layer is a photoelectric conversion layer. 32, and an n-type microcrystalline silicon layer doped with 0.01 atomic% or more of phosphorus, which is a conductivity type determining impurity atom, may be deposited as the reverse conductivity type layer 33 in this order. In this example, an amorphous silicon photoelectric conversion unit is formed.

As the material of the intermediate transmission / reflection layer 4, a silicon composite layer, which is a layer in which a crystalline silicon phase is dispersed in an amorphous silicon oxide matrix, which can be produced by plasma CVD like amorphous silicon or crystalline silicon, is used. . The formation of the silicon composite layer uses, for example, SiH ₄ , CO ₂ , H ₂ , and PH ₃ as a reaction gas, a so-called microcrystal production condition with a large H ₂ / SiH ₄ ratio, and a CO ₂ / SiH ₄ ratio. Is preferably formed by plasma CVD using a range of 2 or more. The plasma CVD conditions at this time are, for example, using a capacitively coupled parallel plate electrode, a power frequency of 10 to 100 MHz, a high frequency power density of 0.01 to 0.5 W / cm ² , a pressure of 50 to 1500 Pa, and a substrate temperature of 150 to 250 ° C. is preferred. When the CO ₂ / SiH ₄ ratio is increased, the oxygen concentration in the film increases monotonously, and the refractive index of the intermediate transmission / reflection layer can be lowered. Specifically, the refractive index of the silicon composite layer with respect to light having a wavelength of 600 nm is preferably 1.7 or more and 2.5 or less.

  The rear photoelectric conversion unit 5 is formed, for example, by laminating semiconductor layers by plasma CVD in the order of pin layers. Specifically, for example, a p-type microcrystalline silicon layer doped with 0.01 atomic% or more of boron, which is a conductivity-determining impurity atom, is used as one conductivity type layer 51, and an intrinsic crystalline silicon layer is used as a photoelectric conversion layer 52. An n-type microcrystalline silicon layer doped with 0.01 atomic% or more of phosphorus which is a conductivity type determining impurity atom may be deposited in this order as a reverse conductivity type layer. In this example, a crystalline silicon photoelectric conversion unit is formed.

The back electrode layer 6 includes a back transparent electrode layer 61 and a back metal electrode layer 62. The back transparent electrode layer 61 is preferably formed of a conductive oxide layer such as ITO, SnO ₂ , or ZnO by a sputtering method or a vapor deposition method. The back transparent electrode layer 61 has a function of increasing the light reflectivity and further preventing chemical change of the photoelectric conversion unit. The back metal electrode layer 62 is preferably formed by sputtering or vapor deposition of at least one material selected from Al, Ag, Au, Cu, Pt, and Cr.

  As shown in FIG. 1, two photoelectric conversion units may be used, but a thin film photoelectric conversion device including three photoelectric conversion units, a so-called triple cell may be used, and three or more photoelectric conversion units may be stacked. As an example of a triple cell, there are three photoelectrics in the order of amorphous silicon photoelectric conversion unit / amorphous silicon germanium photoelectric conversion unit using amorphous silicon germanium in a substantial i layer / crystalline silicon photoelectric conversion unit. Conversion units may be stacked. Further, three photoelectric conversion units may be stacked in the order of amorphous silicon photoelectric conversion unit / crystalline silicon photoelectric conversion unit / crystalline silicon photoelectric conversion unit.

  In the embodiment of the present invention, after the n-type silicon composite layer is formed, it is exposed to the atmosphere and treated with atmospheric pressure plasma into which a mixed gas of oxygen-containing vapor and nitrogen or a rare gas is introduced. It is characterized by that.

  That is, in the manufacturing process of the multilayer thin film photoelectric conversion device of the first embodiment shown in FIG. 1, after the n-type silicon composite layer 4 of FIG. 1 is formed, it is exposed to the atmosphere and subjected to atmospheric pressure plasma treatment, and then the n-type. The crystalline silicon photoelectric conversion unit 5 of FIG. 1 is formed without forming a silicon composite layer. As the oxygen-containing steam, oxygen or dry air is desirable because it is highly safe and inexpensive. As a diluent gas, nitrogen is desirable because it is highly safe and inexpensive. When oxygen is used as the oxidant vapor and nitrogen is used as the diluent gas, the oxygen concentration is preferably 10 to 300 ppm, and more preferably 50 to 150 ppm. The atmospheric pressure plasma is desirably generated by applying a pulsed high voltage between parallel plate electrodes with a minute interval. By making the voltage pulse, the occurrence of arc discharge can be suppressed.

  The surface of the silicon composite film 4 subjected to the atmospheric pressure plasma treatment preferably has a contact angle with pure water of 20 ° or less, and more preferably 10 ° or less. This is because the contact angle is a measure of surface modification by atmospheric pressure plasma.

  Hereinafter, examples according to the present invention and comparative examples according to the prior art will be described in detail. In the drawings, the same members are denoted by the same reference numerals, and redundant description is omitted. Moreover, this invention is not limited to a following example, unless the meaning is exceeded.

Example 1
As Example 1 of the present invention, a stacked thin film photoelectric conversion device as shown in FIG. 1 was prepared. As the transparent substrate 1, a glass substrate of 1.8 mm × 125 mm × 125 mm was used, and 25 1 cm separation type thin film solar cells were produced. A transparent electrode layer 2 was formed on the transparent substrate 1. The transparent electrode layer 2 was formed on the transparent substrate 1 by a thermal CVD method with a SnO ₂ film having minute pyramidal surface irregularities and an average thickness of 700 nm. The sheet resistance of the obtained transparent electrode layer 2 was about 14Ω / □. The haze ratio measured with a C light source was 12%, and the average height difference d of the surface irregularities was about 100 nm. The haze ratio was measured based on JISK7136.

  On the transparent electrode layer 2 as described above, an amorphous silicon photoelectric conversion unit 3, an n-type silicon composite layer 4 as an intermediate transmission / reflection layer, and a crystalline silicon photoelectric conversion unit 5 were formed. Furthermore, the back surface transparent electrode layer 61 and the back surface metal electrode layer 62 were sequentially formed as the back surface electrode layer 6 to produce a stacked thin film solar cell as shown in FIG.

  Specifically, on the transparent electrode layer 2, a p-type layer 31 of a p-type amorphous silicon carbide layer having a thickness of 15 nm, an intrinsic amorphous silicon photoelectric conversion layer 32 having a thickness of 300 nm, and a 15-nm thickness. An amorphous photoelectric conversion unit 3 composed of the n-type microcrystalline silicon layer 33 was formed by plasma CVD. Subsequently, an n-type silicon composite layer 4 having a thickness of 50 nm was formed by plasma CVD. After that, atmospheric pressure plasma treatment using a mixed gas of oxygen and nitrogen was performed. The concentration of oxygen was 250 ppm. Atmospheric pressure plasma applied a pulsed voltage and used a power of 1 kW. After atmospheric pressure plasma, pure water was dropped on the surface of the n-type silicon composite layer 4 and the contact angle was measured. As a result, it was 3.6 ° as shown in FIG. In addition, surface tension was measured 3 times using the contact angle meter (PCA-1 (made by Kyowa Interface Science)), and the arithmetic mean value was used. After the atmospheric pressure plasma treatment, a p-type microcrystalline silicon layer 51 having a thickness of 15 nm is formed in vacuum without forming the same n-type silicon composite layer as that formed before exposure to the atmosphere. A crystalline silicon photoelectric conversion layer unit 5 including an intrinsic crystalline silicon layer 52 having a thickness of 5 μm and an n-type microcrystalline silicon layer 53 having a thickness of 15 nm was formed by plasma CVD.

  Thereafter, on the crystalline silicon photoelectric conversion layer unit 5, as the back electrode layer 6, a back transparent electrode layer 61 of an Al-doped ZnO layer having a thickness of 90 nm and a back metal electrode layer 62 of an Ag layer having a thickness of 200 nm are formed. And sequentially formed by sputtering.

Further, a separation groove having a width of 70 μm that penetrates the front photoelectric conversion unit 3, the intermediate transmission / reflection layer 4, the rear photoelectric conversion unit 5, and the back electrode layer 6 by laser scribing using the second harmonic of the YAG laser (wavelength 532 nm) To form a solar cell having an area of 1 cm ² . At this time, the energy density of the laser beam was set to 0.7 J / cm ² and the processing speed was set to 600 mm / s.

The thin film photoelectric conversion device of Example 1 thus obtained was irradiated with light of air mass (AM) 1.5 at a light intensity of 100 mW / cm ² and the output characteristics were measured. The open circuit voltage (Voc) is 1.384 V, the short circuit current density (Jsc) is 12.52 mA / cm ² , the fill factor (FF) is 0.735, and the conversion efficiency (Eff) is 12.73%. there were.

(Comparative Example 1)
Comparative Example 1 was different from Example 1 only in that it was exposed to the atmosphere without performing atmospheric pressure plasma treatment. When the output characteristics of the thin film solar cell of Comparative Example 1 were measured in the same manner as in Example 1, Voc was 1.379 V, Jsc was 12.48 mA / cm ² , FF was 0.731, and Eff was 12.58. %Met.

  In Comparative Example 1, the initial Eff was slightly lower.

(Comparative Example 2)
Comparative Example 2 was different from Example 1 in that after the amorphous photoelectric conversion unit 3 was formed, it was exposed to the atmosphere and then subjected to atmospheric pressure plasma treatment. That is, after the atmospheric pressure plasma treatment, the intermediate transmission / reflection layer 4, the rear photoelectric conversion unit 5, and the back electrode layer are formed without forming the same n-type semiconductor layer as that formed before exposure to the atmosphere in vacuum. When the output characteristics of the thin film solar cell of Comparative Example 2 in which 6 was sequentially formed were measured in the same manner as in Example 1, Voc was 1.168 V, Jsc was 11.63 mA / cm ² , FF was 0.508, And Eff was 6.904%.

    In Comparative Example 2, the initial Eff was lower than that in Example 1. In particular, Voc and FF were lower than in Example 1.

(Comparative Example 3)
Comparative Example 3 was different from Comparative Example 2 only in that the atmospheric pressure plasma treatment was not performed after exposure to the atmosphere after the amorphous photoelectric conversion unit 3 was formed. When the output characteristics of the thin-film solar cell of Comparative Example 3 were measured in the same manner as in Example 1, Voc was 1.371 V, Jsc was 11.69 mA / cm ² , FF was 0.7500, and Eff was 12.02. %Met.

  In Comparative Example 3, the initial Eff was lower than that in Example 1.

(Comparative Example 4)
Comparative Example 4 was different from Example 1 only in that the film was formed without being exposed to the atmosphere. When the output characteristics of the thin film solar cell of Comparative Example 4 were measured in the same manner as in Example 1, Voc was 1.382 V, Jsc was 12.48 mA / cm ² , FF was 0.731, and Eff was 12.61. %Met.

  In Comparative Example 4, the initial Eff was lower than that in Example 1.

  Table 1 summarizes the results of Example 1 and Comparative Examples 1 to 4.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Transparent electrode layer 3 Amorphous silicon photoelectric conversion unit which is a front photoelectric conversion unit 3 1 Amorphous silicon carbide layer which is one conductivity type layer in a front photoelectric conversion unit 3 2 In a front photoelectric conversion unit I-type amorphous silicon photoelectric conversion layer that is a photoelectric conversion layer 3 3 n-type layer that is a reverse conductivity type layer in the front photoelectric conversion unit 4 transparent intermediate reflection layer n-type silicon composite layer 5 crystal that is the rear photoelectric conversion unit Non-doped i-type crystalline silicon photoelectric conversion layer, which is a photoelectric conversion layer in the rear photoelectric conversion unit 5 1, p-type microcrystalline silicon layer, which is one conductive type layer in the rear photoelectric conversion unit 5 1 5 3 n-type microcrystalline silicon layer which is a reverse conductivity type layer in the rear photoelectric conversion unit 6 Back electrode 6 1 Transparent electrode layer 6 2 Metal electrode layer

Claims (5)

A method for producing a laminated thin film photoelectric conversion device including at least an amorphous photoelectric conversion unit, an n-type silicon composite layer, and a crystalline photoelectric conversion unit in order from the light incident side,
The photoelectric conversion unit includes, in order from the light incident side, one conductivity type layer, a substantially intrinsic semiconductor photoelectric conversion layer, and a reverse conductivity type layer. The one conductivity type layer is a p-type layer, and the reverse conductivity type. The layer is an n-type layer, and the n-type silicon composite layer is an n-type layer in which a silicon crystal phase is mixed in an amorphous alloy of silicon and oxygen,
Forming an amorphous photoelectric conversion unit;
forming an n-type silicon composite layer;
Exposing the formed n-type silicon composite layer to the atmosphere;
A step of performing atmospheric pressure plasma treatment on the n-type silicon composite layer exposed to the atmosphere in a state where a mixed gas of a dilution gas composed of nitrogen or a rare gas and an oxygen-containing vapor is introduced;
And a step of forming a p-type semiconductor layer of the crystalline photoelectric conversion unit in a reduced pressure state. 2. The stacked thin film photoelectric device according to claim 1, wherein there is no step of further forming the n-type silicon composite layer between the step of performing the atmospheric pressure plasma treatment and the step of forming the p-type semiconductor layer. A method for manufacturing a conversion device. The method for manufacturing a stacked thin film photoelectric conversion device according to claim 1, wherein the dilution gas is nitrogen, and the oxygen-containing vapor is oxygen or dry air. 4. The method for manufacturing a stacked thin film photoelectric conversion device according to claim 1, wherein a flow rate ratio of oxygen to nitrogen in the mixed gas is 10 ppm or more and 300 ppm or less. 5. The atmospheric pressure plasma treatment conditions are selected such that a water contact angle on the surface of the n-type silicon composite layer is 10 ° or less for 1 hour after the step of performing the atmospheric pressure plasma treatment. 5. A method for producing a stacked thin-film photoelectric conversion device according to any one of 4 above.