JP5036663B2 - Thin film solar cell and manufacturing method thereof - Google Patents

Thin film solar cell and manufacturing method thereof Download PDF

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JP5036663B2
JP5036663B2 JP2008226022A JP2008226022A JP5036663B2 JP 5036663 B2 JP5036663 B2 JP 5036663B2 JP 2008226022 A JP2008226022 A JP 2008226022A JP 2008226022 A JP2008226022 A JP 2008226022A JP 5036663 B2 JP5036663 B2 JP 5036663B2
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power generation
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generation layer
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solar cell
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JP2010062302A (en
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幹雄 山向
弘也 山林
秀忠 時岡
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三菱電機株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description

  The present invention relates to a thin film solar cell and a method for manufacturing the same, and more particularly to a thin film solar cell having an amorphous semiconductor thin film photoelectric conversion layer and a microcrystalline semiconductor thin film photoelectric conversion layer and a method for manufacturing the same.

  In recent years, in order to realize a solar cell that has both high and stable photoelectric conversion efficiency at the single crystal silicon solar cell level, large area and low cost at the amorphous silicon solar cell level, the microcrystalline silicon to the photoelectric conversion layer Use is under consideration. In particular, a thin film solar cell in which a microcrystalline silicon thin film photoelectric conversion layer is formed by using a thin film formation technique by chemical vapor deposition (hereinafter referred to as a CVD method) similar to that for producing amorphous silicon has attracted attention. .

  However, the photoelectric conversion efficiency of the microcrystalline silicon thin-film solar cell manufactured by the above method is only equivalent to the photoelectric conversion efficiency of the amorphous silicon solar cell. As a major factor, the defect density in the obtained microcrystalline silicon thin film layer is high. The reason for this high defect density is that, in the conventional structure, a transparent conductive film having a concavo-convex shape is formed as a texture structure for light scattering on the surface on which the microcrystalline silicon layer is formed. In some cases, the film quality is greatly deteriorated by the uneven shape. That is, the unevenness of the transparent conductive film increases structural defects induced in the microcrystalline silicon layer formed thereon, and deteriorates the carrier transport property in the film thickness direction.

  In particular, in a solar cell, the crystal grain boundary in the semiconductor film becomes a leakage current generation path and a recombination annihilation region of photoexcited carriers, so the increase in crystal grain boundary due to the small crystal grain size of the crystalline silicon thin film layer, Formation of crystal grain boundaries due to collision between grown crystal grains has led to a decrease in open-circuit voltage characteristics and a decrease in fill factor. Therefore, it is obvious that the unevenness on the surface of the transparent conductive film on which the crystalline semiconductor layer is formed should be as small as possible in order to reduce defects in the crystalline semiconductor layer. However, the irregular shape on the surface of the transparent conductive film causes so-called light confinement that increases the value of current generated by light absorption in the photoelectric conversion layer by causing irregular reflection of light and increasing the optical path length in the silicon film. There is an important function called effect.

  Therefore, as a method for achieving both the light confinement effect and the film quality of the crystalline semiconductor layer, it has been studied to relax the uneven shape on the surface of the transparent conductive film. For example, Patent Document 1 discloses that the light receiving surface side transparent electrode having unevenness is etched to reduce the unevenness. Patent Document 2 discloses that an insulating film having a thickness of 1 nm to 10 nm is formed on a transparent conductive film having an uneven shape so as to relax the uneven shape. Patent Document 3 discloses that the uneven shape is relaxed by increasing the film thickness of the amorphous silicon-based thin film photoelectric conversion layer.

JP 2000-252499 A Japanese Patent Publication No. 5-74951 JP 2004-260014 A

  However, as described above, there are some problems in the technology for relaxing the uneven shape. In the technique of Patent Document 1, since the light confinement effect is weakened when the uneven shape of the light-receiving surface side transparent electrode is relaxed, it is not possible to increase the photoelectric conversion efficiency. In the technique of Patent Document 2, the object is amorphous silicon, and a film thickness of about 1 nm to 10 nm has little effect on the formation of microcrystalline silicon. Moreover, when the amorphous layer is made thick as in the technique of Patent Document 3, incident light is absorbed more by the amorphous layer, and the short-circuit current of the microcrystalline silicon-based thin film photoelectric conversion layer is greatly reduced. There's a problem.

  The present invention has been made in view of the above, and in a thin film solar cell having an amorphous semiconductor thin film photoelectric conversion layer and a microcrystalline semiconductor thin film photoelectric conversion layer, a good light confinement by a texture structure for light scattering. It aims at obtaining the thin film solar cell which has a high photoelectric conversion efficiency which has the effect and the fall of the photoelectric conversion characteristic resulting from this texture structure was prevented, and its manufacturing method.

  In order to solve the above-described problems and achieve the object, a thin-film solar cell according to the present invention includes a first electrode layer made of a transparent conductive film and an amorphous semiconductor film on an insulating translucent substrate. A thin film solar cell in which a first power generation layer that performs conversion, a second power generation layer that includes a microcrystalline semiconductor film and performs photoelectric conversion, and a second electrode layer that includes a conductive film that reflects light are stacked in this order. The first electrode layer has a concavo-convex shape on a surface on the first power generation layer side, and the first power generation layer corresponds to the concavo-convex shape of the first electrode layer. A concavo-convex shape is formed on the side, and the upper surface of the convex portion is a surface substantially parallel to the in-plane direction of the insulating light-transmitting substrate.

  According to the present invention, in a thin film solar cell having an amorphous semiconductor thin film photoelectric conversion layer and a microcrystalline semiconductor thin film photoelectric conversion layer as photoelectric conversion layers, an increase in the amount of light absorption in the photoelectric conversion layer due to the light confinement effect, It is possible to achieve both good carrier transport characteristics in the film thickness direction in the crystalline semiconductor thin film photoelectric conversion layer, and to achieve a thin film solar cell having high photoelectric conversion efficiency.

  Embodiments of a thin film solar cell and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings.

Embodiment 1 FIG.
FIG. 1 is a plan view showing a schematic configuration of a thin film solar cell module (hereinafter referred to as a module) 10 which is a tandem thin film solar cell according to a first embodiment of the present invention. FIG. 2A is a diagram for explaining a cross-sectional structure of the module 10, and is a cross-sectional view of a main part taken along a line AA ′ in FIG. 1.

  As shown in FIGS. 1 and 2-1, the module 10 according to the first embodiment includes a plurality of strip-like (rectangular) cells C, and these cells C are electrically connected in series. Have. As shown in FIG. 2A, the cell C is formed on the insulating transparent substrate 1, the transparent electrode layer 2 formed on the insulating transparent substrate 1 and serving as the first electrode layer, and the transparent electrode layer 2. A first power generation layer 3, a second power generation layer 4 formed on the first power generation layer 3, and a back electrode layer 5 formed on the second power generation layer 4 and serving as a second electrode layer.

  The transparent electrode layer 2 formed on the insulating light-transmitting substrate 1 has stripe-shaped first layers extending in a direction substantially parallel to the short side direction of the insulating light-transmitting substrate 1 and reaching the insulating light-transmitting substrate 1. One groove G1 is formed. By embedding the first power generation layer 3 and the second power generation layer 4 in the first groove G1, the transparent electrode layer 2 is formed separately for each cell so as to straddle the adjacent cells C. Further, the first power generation layer 3 and the second power generation layer 4 formed on the transparent electrode layer 2 are arranged in a direction substantially parallel to the short direction of the insulating light-transmitting substrate 1 at a location different from the first groove G1. A stripe-shaped second groove G <b> 2 that extends and reaches the transparent electrode layer 2 is formed. The back electrode layer 5 is connected to the transparent electrode layer 2 by embedding the back electrode layer 5 in the second groove G2. And since this transparent electrode layer 2 straddles the adjacent cell, the back electrode layer 5 and the transparent electrode layer 2 of the adjacent cell are electrically connected.

  The back electrode layer 5, the second power generation layer 4, and the first power generation layer 3 are striped third layers reaching the transparent electrode layer 2 at locations different from the first groove G 1 and the second groove G 2. A groove G3 is formed to separate each cell C. In this way, the transparent electrode layer 2 of the cell C is connected to the back electrode layer 5 of the adjacent cell C, whereby the adjacent cells C are electrically connected in series.

  The transparent electrode layer 2 is composed of a 1 μm thick zinc oxide (ZnO) film containing aluminum (Al) as a dopant. The transparent electrode layer 2 has a surface texture structure in which an uneven shape is formed on the surface on the first power generation layer 3 side. This texture structure has a function of scattering incident sunlight and improving light use efficiency in the first power generation layer 3 and the second power generation layer 4.

In this embodiment, a ZnO film doped with Al is used as the transparent electrode layer 2, but the transparent electrode layer 2 is not limited to this, and aluminum (Al), gallium (Ga), and indium (In) are used as dopants. , Boron (B), yttrium (Y), silicon (Si), zirconium (Zr), ZnO film using at least one element selected from titanium (Ti), or a transparent conductive film formed by laminating these films Any transparent conductive film having light transparency may be used. In addition to the ZnO film, a film made of a material mainly containing either indium oxide (In 2 O 3 ) or tin oxide (SnO 2 ) may be used.

  The first power generation layer 3 and the second power generation layer 4 have a PN junction or a PIN junction, and are configured by laminating one or more thin film semiconductor layers that generate power by incident light. The first power generation layer 3 is a photoelectric conversion layer made of an amorphous silicon-based thin film, and as shown in FIG. 2-2, a P-type amorphous silicon carbide film (a-SiC film) 6 from the transparent electrode layer 2 side, An I-type amorphous silicon film (a-Si film) 7 and an N-type amorphous silicon film (a-Si film) 8 are provided to form a pin junction. FIG. 2B is a cross-sectional view for explaining the shapes of the transparent electrode layer 2 and the first power generation layer 3 in the module 10.

  The surface of the transparent electrode layer 2 is formed with a concavo-convex shape having small convex portions 2a as a light scattering texture structure. The 1st electric power generation layer 3 has the small convex part 3a, and is provided in the uneven | corrugated shape corresponding to the uneven | corrugated shape of the surface of the transparent electrode layer 2. As shown in FIG. And the front-end | tip part of the uneven | corrugated shaped convex part 3a in the surface at the side of the 2nd electric power generation layer 4 is planarized, and the upper surface of this convex part 3a is made into the surface substantially parallel to the in-plane direction of the insulating translucent board | substrate 1. Yes. That is, the height difference of the uneven shape on the surface of the first power generation layer 3 is relaxed compared to the height difference of the uneven shape formed on the surface of the transparent electrode layer 2.

  The second power generation layer 4 is a microcrystalline silicon-based thin film photoelectric conversion layer, and includes a P-type microcrystalline silicon film (μc-Si film) and an I-type microcrystalline silicon film (μc-Si) from the first power generation layer 3 side. Film) and an N-type microcrystalline silicon film (μc-Si film) (not shown) to form a pin junction.

The back electrode layer 5 is patterned in a shape and position different from those of the first power generation layer 3 and the second power generation layer 4. The back electrode layer 5 is composed of an aluminum (Al) film having a thickness of 200 nm. In this embodiment, an aluminum (Al) film is formed as the back electrode layer 5. However, the back electrode layer 5 is not limited to this, and silver (Ag) having high reflectivity is used as the metal electrode. Alternatively, these may be laminated. Further, a transparent conductive film such as zinc oxide (ZnO), indium tin oxide (ITO), or tin oxide (SnO 2 ) may be formed in order to prevent metal diffusion into silicon.

  Here, an outline of the operation of the module 10 according to the first embodiment will be described. When sunlight enters from the back surface (the surface on which the cell C is not formed) of the insulating translucent substrate 1, free carriers are generated in the first power generation layer 3 and the second power generation layer 4, and current is generated. The current generated in each cell C flows into the adjacent cell C via the transparent electrode layer 2 and the back electrode layer 5, and generates a generated current for the entire module 10.

  In this module 10, a multilayer thin film photoelectric photoelectric layer in which a first power generation layer 3 whose photoelectric conversion layer is an amorphous silicon thin film photoelectric conversion layer and a second power generation layer 4 which is a microcrystalline silicon thin film photoelectric conversion layer are stacked. It has the cell C of a conversion element structure, and each cell C is electrically connected in series. For this reason, the short circuit current as a thin film solar cell is restricted by the smallest value among the current values generated in each cell C. Therefore, it is preferable that the current values of the cells C be equal, and further, the larger the absolute value of the current, the higher the photoelectric conversion efficiency can be expected.

  In the thin-film solar cell according to the first embodiment configured as described above, the surface of the transparent electrode layer 2 is formed with a concavo-convex shape having small convex portions 2a as a texture structure for light scattering. The light incident from the insulating translucent substrate 1 side enters the first power generation layer 3 after being scattered at the interface between the transparent electrode layer 2 having the concavo-convex shape and the first power generation layer 3. The light enters the power generation layer 3 almost obliquely. Then, since light is incident on the first power generation layer 3 at an angle, a substantial optical path of the light is extended and the amount of light absorption in the power generation layer is increased, so that the photoelectric conversion characteristics of the thin film solar cell are improved and output. The current increases. Thereby, the thin film solar cell excellent in conversion efficiency which has a favorable light-diffusion effect is implement | achieved.

  Moreover, according to the thin film solar cell concerning Embodiment 1 as mentioned above, the front-end | tip part of the convex part 3a of the 1st electric power generation layer 3 surface is planarized, and the uneven | corrugated shape of the 1st electric power generation layer 3 surface is relieve | moderated. Therefore, the influence of the uneven shape on the surface of the first power generation layer 3 on the crystal growth of the microcrystalline semiconductor film of the second power generation layer 4 is suppressed, and the microcrystalline semiconductor film in the microcrystalline semiconductor film due to the texture structure for light scattering is suppressed. Structural defects can be reduced. As a result, the microcrystalline semiconductor film of the second power generation layer 4 has a good film quality with few defects, and it is possible to reduce deterioration of carrier transport characteristics in the film thickness direction due to structural defects in the microcrystalline semiconductor film.

  Even when the thickness of the first power generation layer 3 which is an amorphous silicon thin film is reduced, the microcrystalline silicon thin film of the second power generation layer 4 laminated thereon has a good film quality with few defects. Therefore, it becomes easy to control the current value of the cell C by the film thickness of the first power generation layer 3 that is an amorphous silicon thin film, and a thin film solar cell excellent in controllability can be realized.

  Therefore, according to the thin film solar cell according to the first embodiment, an increase in the amount of light absorption in the photoelectric conversion layer due to the light confinement effect of the texture structure for light scattering, and the film thickness direction in the microcrystalline semiconductor thin film photoelectric conversion layer A thin film solar cell having high photoelectric conversion efficiency that satisfies both good carrier transport characteristics has been realized.

  In the above description, the case where amorphous silicon is used for the first power generation layer 3 has been described. However, a pin structure made of an amorphous silicon semiconductor film such as amorphous silicon germanium or amorphous silicon carbide is used. A tandem module 10 in which the first power generation layer 3 and the second power generation layer 4 having a pin structure made of a crystalline silicon-based semiconductor film such as silicon germanium or silicon carbide can be stacked. By setting the power generation layer to such a pin structure, good output characteristics can be obtained.

  Next, a method for manufacturing the module 10 according to the first embodiment configured as described above will be described. FIGS. 3-1 to 3-8 are cross-sectional views for explaining the manufacturing process of the module 10 according to the first embodiment, and are cross-sectional views corresponding to the line segment A-A 'of FIG.

First, the insulating translucent substrate 1 is prepared. As the insulating translucent substrate 1, for example, a flat glass substrate is used (hereinafter referred to as a glass substrate 1). In the present embodiment, a case where an alkali-free glass substrate is used as the glass substrate 1 will be described. In addition, an inexpensive blue plate glass substrate may be used as the glass substrate 1, but in this case, in order to prevent the diffusion of alkali components from the substrate, SiO 2 is formed as an undercoat layer by a plasma chemical vapor deposition (PCVD) method. The film is preferably formed with a thickness of about 100 nm.

  Next, the transparent electrode layer 2 to be the first electrode layer is formed on one surface side of the glass substrate 1 (FIG. 3A). As the transparent electrode layer 2, for example, a 1 μm-thick zinc oxide (ZnO) film containing aluminum (Al) as a dopant is deposited by DC sputtering.

In this embodiment, a ZnO film doped with Al is used as the transparent electrode layer 2, but the transparent electrode layer 2 is not limited to this, and aluminum (Al), gallium (Ga), and indium (In) are used as dopants. , Boron (B), yttrium (Y), silicon (Si), zirconium (Zr), ZnO film using at least one element selected from titanium (Ti), or a transparent conductive film formed by laminating these films Any transparent conductive film having light transparency may be used. In addition to the ZnO film, a film made of a material mainly containing either indium oxide (In 2 O 3 ) or tin oxide (SnO 2 ) may be used.

  In the above description, the transparent electrode layer 2 is formed by the DC sputtering method. However, the method for forming the transparent electrode layer 2 is not limited to this, and physical methods such as a vacuum deposition method and an ion plating method are used. Alternatively, a chemical method such as a spray method, a dip method, or a CVD method may be used.

Thereafter, the glass substrate 1 on which the transparent electrode layer 2 is formed is immersed in, for example, a 1% hydrochloric acid (HCl) aqueous solution for about 30 seconds, washed with pure water for 1 minute or more, and dried. By this etching process, the surface of the transparent electrode layer 2 is roughened to form small convex portions 2a on the surface of the transparent electrode layer 2 (FIG. 3-2). Thereby, for example, an uneven shape having an average depth of 100 nm or more is formed on the surface of the transparent electrode layer 2. However, when the transparent electrode layer 2 such as SnO 2 , ZnO or the like is formed by the CVD method, irregularities are formed on the surface of the transparent electrode layer 2 in a self-organized manner, so that it is necessary to form the irregularities by etching using dilute hydrochloric acid. Absent.

  Next, a part of the transparent electrode layer 2 is cut and removed in a stripe shape in a direction substantially parallel to the short side direction of the insulating translucent substrate 1, and the transparent electrode layer 2 is patterned into a strip shape to obtain a plurality of transparent The electrode layer 2 is separated (FIG. 3-2). The patterning of the transparent electrode layer 2 is performed by forming a first groove G1 having a stripe shape extending in a direction substantially parallel to the short side direction of the insulating light-transmitting substrate 1 and reaching the insulating light-transmitting substrate 1 by a laser scribing method. Do by forming. In addition, in order to obtain a plurality of transparent electrode layers 2 separated from each other within the substrate surface on the glass substrate 1 in this way, a method of etching using a resist mask formed by photolithography or the like, or a metal mask was used. A method such as vapor deposition is also possible.

  Next, the first power generation layer 3 is formed on the transparent electrode layer 2 including the first groove G1 by a plasma CVD method. In the present embodiment, as the first power generation layer 3, a P-type amorphous silicon carbide film (a-SiC film) 6, an I-type amorphous silicon film (a-Si film) 7, an N-type from the transparent electrode layer 2 side. The amorphous silicon film (a-Si film) 8 is sequentially formed (FIG. 3-3). Here, since the 1st electric power generation layer 3 is formed corresponding to the surface shape of the transparent electrode layer 2, the unevenness | corrugation which has the convex part 3a resulting from the surface shape of the transparent electrode layer 2 on the surface of the 1st electric power generation layer 3 A shape is formed.

Next, on the first power generation layer 3 laminated in this way, a coat film 9 which is a sacrificial film in etching described later is formed (FIG. 3-4). The height of the coat film 9 is preferably set such that the surface of the coat film 9 exceeds the height H of the convex portion 3 a, and the film thickness dimension of the coat film 9 is an uneven convex portion in the first power generation layer 3. It is preferable that the average height dimension is 3 times or more. By setting the film thickness of the coat film 9 to such a dimension, the difference between the maximum height and the minimum height of the protrusion after the etching back can be processed to be small. As for the film thickness of the coating film, a thinner one in the range covering the height of the convex portion is more effective for flattening the protrusions, and the film thickness uniformity after the formation is also improved. Here, the height H of the convex part 3a is 0.01-1 micrometer, More preferably, the range of 0.1-0.5 micrometer is preferable. The height H of the convex portion 3a is a height based on the height from the top of the convex portion to the bottom of the concave portion. The average height dimension of the convex portion 3a is a value obtained from the surface shape waveform obtained by measuring the surface irregularity shape over 10 μm 2 with an atomic force microscope, and the surface irregularity specified by the Japanese Industrial Standard JIS B0602-1994. It is the height calculated with the arithmetic average value Ra as the average height dimension. As a material of the coat film 9, for example, a resist can be used. Since the resist has a relatively low viscosity, the surface of the first power generation layer 3 can be covered flat.

  Next, etching using a parallel plate type reactive ion etching (RIE) method is performed, and a part of the convex portion 3a of the first power generation layer 3 and the coating film 9, and more specifically, an N-type a- A part of the Si film 8 and the I-type a-Si film 7 and the coat film 9 are etched back (FIG. 3-5). At this time, the etching conditions are adjusted so that the coat film 9 and the convex portion 3a of the first power generation layer 3 are etched at the same etching rate. Specifically, the etching conditions are adjusted so that the coat film 9, the N-type a-Si film 8, and the I-type a-Si film 7 are etched at the same etching rate. Thus, by making the etching rate of each part the same, the height after etching of each part can be made substantially uniform.

  Further, even if the etching rates of the coat film 9 and the first power generation layer 3 are not the same, the etching conditions are adjusted so that, for example, the etching selectivity of the first power generation layer 3 to the coat film 9 is 1 or more. It is preferable. By adjusting to such a condition, it is possible to prevent the coating film 9 from being etched away before the convex portion 3a of the first power generation layer 3 is flattened and to etch back the convex portion 3a.

  Then, the tip portion of the convex portion 3a is generally etched to flatten the tip portion of the convex portion 3a, and desired flatness is obtained on the upper surface of the convex portion 3a, so that the coat film 9 remains on the surface moderately. At this point, the etching is finished. Thereby, the upper surface of the convex part 3a is made into a surface substantially parallel to the in-plane direction of the insulating translucent substrate 1. As described above, by etching each part at the same etching rate, the height after etching of each part can be made substantially uniform, and the upper part of the convex part 3a of the first power generation layer 3 is removed and the convex part 3a is removed. It is possible to easily and reliably flatten the upper surface of the substrate. Thereby, a flat surface composed of the N-type a-Si film 8 and the I-type a-Si film 7 is obtained on the upper surface of the convex portion 3a.

In the present embodiment, a parallel plate RIE method is used as an etching method, and a resist is employed as the coating film 9. When etching a resist by the parallel plate RIE method, the etching rate between the resist and the silicon thin film can be easily adjusted by adjusting the supply gas ratio of the fluorine-based gas to the oxygen gas in the etching gas used. Therefore, controllability is good. Etching gas at this time includes, for example, tetrafluoromethane (CF 4 ), trifluoromethane (CHF 3 ), hexafluoroethane (C 2 F 6 ), propane octafluoride (C 3 F 8 ), carbon tetrachloride It is possible to use a halogen-based gas alone containing halogen, such as (CCl 4 ) or sulfur hexafluoride (SF 6 ), and an etching gas in which oxygen (O 2 ) or helium (He) is mixed with this gas.

In this embodiment mode, etching is performed with an etching gas in which CF 4 and He are mixed in order to etch the resist and the amorphous silicon at the same etching rate. Then, after etching, the coat film 9 (resist) remaining on the surface is separately removed by, for example, oxygen plasma treatment or chemical treatment (FIGS. 3-6).

Next, the second power generation layer 4 is formed on the first power generation layer 3 by the PCVD method (FIGS. 3-7). In the present embodiment, as the second power generation layer 4, a P-type microcrystalline silicon film (μc-Si film), an I-type microcrystalline silicon film (μc-Si film), an N-type from the first power generation layer 3 side. The microcrystalline silicon films (μc-Si film) are sequentially formed (not shown). In the present embodiment, the second power generation layer 4 is formed after the coating film 9 (resist) is removed, but before the second power generation layer 4 is formed, a flat surface made of the I-type a-Si film 7 is formed. To form a PIN junction, an N-type a-Si film or an N-type μc-Si film may be formed to a thickness of about 30 nm or less. Further, between the first power generation layer 3 and the second power generation layer 4, a zinc oxide (ZnO), indium tin oxide (ITO), tin oxide (SnO 2), a light-transmitting property such as silicon monoxide (SiO) An intermediate layer made of a conductive film may be formed.

  Then, the semiconductor layers (first power generation layer 3 and second power generation layer 4) thus laminated are patterned by laser scribing in the same manner as the transparent electrode layer 2. That is, a part of the semiconductor layer (the first power generation layer 3 and the second power generation layer 4) is cut and removed in a stripe shape in a direction substantially parallel to the short side direction of the insulating translucent substrate 1, and the semiconductor layer (the first power generation layer 3). The first power generation layer 3 and the second power generation layer 4) are patterned into strips and separated. The patterning of the semiconductor layers (the first power generation layer 3 and the second power generation layer 4) is performed in a direction substantially parallel to the short direction of the insulating translucent substrate 1 at a location different from the first groove G1 by a laser scribing method. This is performed by forming a stripe-like second groove G <b> 2 that extends and reaches the transparent electrode layer 2.

Next, the back electrode layer 5 to be the second electrode layer is formed on the second power generation layer 4 by a sputtering method (FIGS. 3-8). As the back electrode layer 5, for example, an aluminum (Al) film having a thickness of 200 nm is deposited by sputtering. In the present embodiment, an aluminum (Al) film having a film thickness of 200 nm is formed as the back electrode layer 5, but the back electrode layer 5 is not limited to this, and silver (Ag) having a high reflectivity as a metal electrode. May be used, or these may be laminated. Further, a transparent conductive film such as zinc oxide (ZnO), indium tin oxide (ITO), or tin oxide (SnO 2 ) may be formed in order to prevent metal diffusion into silicon.

  After the formation of the back electrode layer 5, a part of the back electrode layer 5 and the semiconductor layer (the first power generation layer 3 and the second power generation layer 4) is striped in a direction substantially parallel to the short side direction of the insulating translucent substrate 1. The metal layer and the semiconductor layer (the first power generation layer 3 and the second power generation layer 4) are patterned into strips and separated into a plurality of cells C. Patterning of the metal layer and the semiconductor layer (the first power generation layer 3 and the second power generation layer 4) is performed by a laser scribing method at a location different from the first groove G1 and the second groove G2, in the insulating light-transmitting substrate 1. This is performed by forming a stripe-like third groove G3 extending in a direction substantially parallel to the short direction of and reaching the transparent electrode layer 2. Since it is difficult to directly absorb the laser in the back electrode layer 5 having a high reflectance, the laser light energy is absorbed in the semiconductor layers (the first power generation layer 3 and the second power generation layer 4), and the semiconductor layer (first By separating the metal layer together with the power generation layer 3 and the second power generation layer 4), the metal layers are separated to correspond to the plurality of cells C. Thus, the module 10 having the cell C as shown in FIG.

With respect to the thin film solar cell produced by the method for manufacturing the thin film solar cell according to the first embodiment described above, AM (air mass) 1.5 light is emitted at a light amount of 100 mW / cm 2 using a solar simulator. Incident from the substrate side, the short-circuit current (mA / cm 2 ) was measured, and the characteristics as a solar cell were evaluated. As a result, the open circuit voltage is 1.35 V, the short-circuit current is 12.5 mA / cm 2 , the fill factor is 0.74, and the photoelectric conversion efficiency is 12.5%, and good output characteristics are obtained. confirmed.

  Further, in order to quantitatively examine the crystallinity of the μc-Si film layer, a P-type microcrystalline silicon film (μc-Si film), an I-type microcrystalline silicon is used as the second power generation layer 4 in the manufacturing process described above. When X-ray diffraction was performed on the film formed up to the film (μc-Si film), the ratio I220 / I111 of the integrated intensity I220 of the (220) X-ray diffraction peak and the integrated intensity I111 of the (111) X-ray diffraction peak was It was 4.0, and it was found that the μc-Si film layer was mainly composed of crystal grains grown in a columnar shape in a direction perpendicular to the substrate. By having such a structure, good carrier transport in the film thickness direction can be achieved by reducing defects in the crystalline semiconductor layer, and high photoelectric conversion efficiency can be obtained.

  According to the method for manufacturing a thin-film solar cell according to the first embodiment as described above, an uneven shape having small convex portions 2 a as a texture structure for light scattering is formed on the surface of the transparent electrode layer 2. Light incident from the side of the insulating translucent substrate 1 is scattered at the interface between the transparent electrode layer 2 having the concavo-convex shape and the first power generation layer 3 and then enters the first power generation layer 3 to generate the first power generation. It is incident on the layer 3 substantially obliquely. Then, since light is incident on the first power generation layer 3 at an angle, a substantial optical path of the light is extended and the amount of light absorption in the power generation layer is increased, so that the photoelectric conversion characteristics of the thin film solar cell are improved and output. The current increases. Therefore, according to the method for manufacturing a thin film solar cell according to the first embodiment, a thin film solar cell having a good light diffusion effect and excellent in conversion efficiency can be produced.

  Moreover, according to the manufacturing method of the thin film solar cell concerning Embodiment 1 as mentioned above, the front-end | tip part of the convex part 3a of the 1st electric power generation layer 3 surface is planarized, and the uneven | corrugated shape of the 1st electric power generation layer 3 surface is relieve | moderated. Therefore, the influence of the irregular shape on the surface of the first power generation layer 3 on the crystal growth of the microcrystalline semiconductor film of the second power generation layer 4 is suppressed, and the structure in the microcrystalline semiconductor film resulting from the texture structure for light scattering Defects can be reduced. Thereby, a microcrystalline semiconductor film having a good film quality can be formed as the second power generation layer 4, and deterioration of carrier transport characteristics in the film thickness direction due to structural defects in the microcrystalline semiconductor film can be reduced.

  Even when the thickness of the first power generation layer 3 which is an amorphous silicon thin film is reduced, the microcrystalline silicon thin film of the second power generation layer 4 laminated thereon has a good film quality with few defects. Therefore, it becomes easy to control the current value of the cell C by the film thickness of the first power generation layer 3 which is an amorphous silicon thin film, and a thin film solar cell excellent in controllability can be manufactured.

  Therefore, according to the method for manufacturing the thin-film solar cell according to the first embodiment, an increase in the amount of light absorption in the photoelectric conversion layer due to the light confinement effect of the light scattering texture structure, and the film in the microcrystalline semiconductor thin-film photoelectric conversion layer A thin-film solar cell having high photoelectric conversion efficiency that satisfies both good carrier transport characteristics in the thickness direction can be manufactured.

Embodiment 2. FIG.
In the first embodiment, the case where the uneven shape in contact with the second power generation layer 4 is relaxed by etching back the coating film 9 and the first power generation layer 3 is described. However, the uneven shape in contact with the second power generation layer 4 is relaxed. The method to do is not limited to this. In the second embodiment, a case will be described in which, after an intermediate layer is formed on the first power generation layer 3, the uneven shape in contact with the second power generation layer 4 is relaxed by relaxing the uneven shape of the intermediate layer.

  A schematic configuration of a thin film solar cell module (hereinafter referred to as a module) 20 that is a tandem thin film solar cell according to a second embodiment of the present invention is the same as that of the module 10 according to the first embodiment (FIG. 1). . FIG. 4A is a diagram for explaining a cross-sectional structure of the module 20, and is a cross-sectional view of a main part taken along a line segment A-A ′ in FIG. 1.

  As illustrated in FIGS. 1 and 4-1, the module 20 according to the second embodiment includes a plurality of strip-shaped (rectangular) cells C, and the cells C are connected in series. As shown in FIG. 4A, the cell C is formed on the insulating transparent substrate 1, the transparent electrode layer 2 formed on the insulating transparent substrate 1 and serving as the first electrode layer, and the transparent electrode layer 2. The first power generation layer 23, the intermediate layer 12 formed on the first power generation layer 23, the second power generation layer 4 formed on the intermediate layer 12, and the second electrode layer formed on the second power generation layer 4 The back electrode layer 5 is provided. In addition, about the same member as the module 10 concerning Embodiment 1, detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

The intermediate layer 12 is made of a light-transmitting conductive film such as zinc oxide (ZnO), indium tin oxide (ITO), tin oxide (SnO 2 ), or silicon monoxide (SiO).

  FIG. 4B is a diagram for explaining the shapes of the transparent electrode layer 2, the first power generation layer 23, and the intermediate layer 12 in the module 20. The surface of the transparent electrode layer 2 has an uneven shape having small protrusions 2a. The first power generation layer 23 has small convex portions 23 a and is provided in an uneven shape corresponding to the uneven shape on the surface of the transparent electrode layer 2.

  The intermediate layer 12 has a small convex portion 12 a and is provided in an uneven shape corresponding to the uneven shape on the surface of the first power generation layer 23. And the front-end | tip part of the uneven | corrugated shaped convex part 12a in the surface by the side of the 2nd electric power generation layer 4 is planarized, and the upper surface of this convex part 12a is made into the surface substantially parallel to the in-plane direction of the insulating translucent board | substrate 1. Yes. That is, the height difference of the uneven shape on the surface of the intermediate layer 12 is relaxed compared to the height difference of the uneven shape formed on the surfaces of the transparent electrode layer 2 and the first power generation layer 23.

  According to the thin-film solar cell according to the second embodiment configured as described above, the surface of the transparent electrode layer 2 is formed with a concavo-convex shape having small convex portions 2a as a texture structure for light scattering. The light incident from the insulating translucent substrate 1 side enters the first power generation layer 3 after being scattered at the interface between the transparent electrode layer 2 having the concavo-convex shape and the first power generation layer 3. The light enters the power generation layer 3 almost obliquely. Then, since light is incident on the first power generation layer 3 at an angle, a substantial optical path of the light is extended and the amount of light absorption in the power generation layer is increased, so that the photoelectric conversion characteristics of the thin film solar cell are improved and output. The current increases. Thereby, the thin film solar cell excellent in conversion efficiency which has a favorable light-diffusion effect is implement | achieved.

  Moreover, according to the thin film solar cell concerning Embodiment 2 as mentioned above, since the front-end | tip part of the convex part 12a of the intermediate | middle layer 12 surface is planarized, the uneven | corrugated shape of the intermediate | middle layer 12 surface is eased. In addition, the influence of the uneven shape on the surface of the intermediate layer 12 on the crystal growth of the microcrystalline semiconductor film of the second power generation layer 4 is suppressed, and structural defects in the microcrystalline semiconductor film due to the texture structure for light scattering are reduced. Can do. As a result, the microcrystalline semiconductor film of the second power generation layer 4 has a good film quality with few defects, and it is possible to reduce deterioration of carrier transport characteristics in the film thickness direction due to structural defects in the microcrystalline semiconductor film.

  Even when the thickness of the first power generation layer 3 that is an amorphous silicon thin film is reduced, the microcrystalline silicon thin film of the second power generation layer 4 laminated on the intermediate layer 12 has a defect. Since it has few good film quality, it becomes easy to control the current value of the cell C by the film thickness of the first power generation layer 3 which is an amorphous silicon thin film, and a thin film solar cell excellent in controllability is realized. it can.

  In addition, according to the thin film solar cell according to the second embodiment, a part of incident light is reflected by the intermediate layer 12, and the first power generation layer 3 that is a power generation layer located on the light incident side of the intermediate layer 12 is used. Therefore, the current generated in the first power generation layer 3 can be increased. Since the optical confinement effect and the crystallinity of the amorphous silicon thin film photoelectric conversion layer are improved, the amorphous silicon thin film necessary for obtaining the same current value can be made thin. It is possible to suppress a decrease in photoelectric conversion characteristics due to photodegradation that becomes conspicuous in accordance with an increase in the thickness of the system thin film, and a highly reliable thin film solar cell is realized.

  Therefore, according to the thin film solar cell according to the second embodiment, the increase in the amount of light absorption in the photoelectric conversion layer due to the light confinement effect of the light scattering texture structure and the film thickness direction in the microcrystalline semiconductor thin film photoelectric conversion layer A thin film solar cell having high photoelectric conversion efficiency that satisfies both good carrier transport characteristics and high reliability has been realized.

  Next, a method for manufacturing the module 20 according to the second embodiment configured as described above will be described. FIGS. 5-1 to 5-5 are cross-sectional views for explaining the manufacturing process of the module 20 according to the second embodiment, and are cross-sectional views corresponding to the line segment A-A ′ of FIG. 1. Detailed description of the same steps as those in the first embodiment will be omitted.

First, a flat glass substrate 1 is prepared as the insulating translucent substrate 1. Next, the transparent electrode layer 2 having a texture structure is formed on the surface of the glass substrate 1. As the transparent electrode layer 2, a transparent conductive film made of doped tin oxide (SnO 2 : F) having fluorine and having a convex portion 2a on the surface is formed. Then, a part of the transparent electrode layer 2 is cut and removed in a stripe shape in a direction substantially parallel to the short side direction of the insulating translucent substrate 1, and the transparent electrode layer 2 is patterned into a strip shape. Separate into layer 2.

  Next, the first power generation layer 23 is formed on the transparent electrode layer 2 by a plasma CVD method (FIG. 5-1). In the present embodiment, a P-type amorphous silicon carbide film (a-SiC film) 6, a buffer layer 13, and an I-type amorphous silicon film (a-Si film) 7 from the transparent electrode layer 2 side as the first power generation layer 23. Then, an N-type amorphous silicon film (a-Si film) 8 is sequentially formed. Here, since the 1st electric power generation layer 23 is formed corresponding to the surface shape of the transparent electrode layer 2, the unevenness | corrugation which has the convex part 23a resulting from the surface shape of the transparent electrode layer 2 on the surface of the 1st electric power generation layer 23 A shape is formed.

  Thereafter, a zinc oxide (ZnO) film is formed as the intermediate layer 12 (FIG. 5-2). Here, since the intermediate layer 12 is formed corresponding to the surface shape of the first power generation layer 23, the surface of the intermediate layer 12 has a concavo-convex shape having convex portions 12 a due to the surface shape of the first power generation layer 23. It is formed.

Next, on the intermediate layer 12 laminated in this way, a coat film 14 which is a sacrificial film in etching described later is formed (FIG. 5-3). The height of the coat film 14 is preferably set such that the surface of the coat film 14 exceeds the height H ′ of the convex portion 12 a, and the film thickness dimension of the coat film 14 is the convex and concave portion 12 a having an uneven shape in the intermediate layer 12. It is preferable that the average height dimension is at least one time. By setting the film thickness dimension of the coat film 14 to such a dimension, the difference between the maximum height and the minimum height of the protrusion after the etching back can be processed to be small. As for the film thickness of the coating film, a thinner one in the range covering the height of the convex portion is more effective for flattening the protrusions, and the film thickness uniformity after the formation is also improved. Here, the height H of the convex part 12a is 0.01-1 micrometer, More preferably, the range of 0.1-0.5 micrometer is preferable. The height H of the convex portion 12a is a height based on the height from the top of the convex portion to the bottom of the concave portion. The average height dimension of the convex part 12a consists of a value obtained from the surface shape waveform obtained by measuring the surface irregularity shape over 10 μm 2 with an atomic force microscope, and the surface irregularity specified by the Japanese Industrial Standard JIS B0602-1994. It is the height calculated with the arithmetic average value Ra as the average height dimension. As a material of the coating film 14, for example, an acrylic resin is used.

  Next, etching using a parallel plate type reactive RIE method is performed to etch back part of the intermediate layer 12 and the coating film 14 (FIG. 5-4). At this time, the etching conditions are adjusted so that the coat film 14 and the convex portion 12a of the intermediate layer 12 are etched at the same etching rate. Thus, by making the etching rate of each part the same, the height after etching of each part can be made substantially uniform.

  Even if the etching rates of the coat film 14 and the intermediate layer 12 are not the same, it is preferable to adjust the etching conditions so that, for example, the etching selectivity of the intermediate layer 12 to the coat film 14 is 1 or more. By adjusting to such conditions, it is possible to prevent the coating film 14 from being etched away before the convex portion 12a of the intermediate layer is flattened, and to etch back the convex portion 12a.

As an etching gas, a mixed etching gas of tetrafluoromethane (CF 4 ) and oxygen (O 2 ) can be used. In addition, for example, tetrafluoromethane (CF 4 ), trifluoromethane (CHF 3 ), hexafluoroethane (C 2 F 6 ), propane octafluoride (C 3 F 8 ), carbon tetrachloride (CCl) 4 ), a halogen-based gas alone containing halogen, such as sulfur hexafluoride (SF 6 ), or an etching gas in which oxygen (O 2 ) or helium (He) is mixed with this gas can be used.

  Then, the tip of the convex portion 12a is generally etched to flatten the tip of the convex portion 12a, and a desired flatness is obtained on the upper surface of the convex portion 12a, and the coat film 14 remains on the surface moderately. At this point, the etching is finished. Thereby, the upper surface of the convex part 12a is made into a surface substantially parallel to the in-plane direction of the insulating translucent substrate 1. As described above, by etching each part at the same etching rate, the height after etching of each part can be made substantially uniform, and the upper part of the convex part 12a of the intermediate layer 12 is removed and the upper surface of the convex part 12a is removed. Can be flattened easily and reliably. Thereby, a flat surface composed of the coating film 14 and the intermediate layer 12 is obtained. After etching, the coat film 14 remaining on the surface is separately removed by, for example, oxygen plasma treatment or chemical treatment.

  Next, the second power generation layer 4 is formed on the intermediate layer 12 by the PCVD method. In the present embodiment, as the second power generation layer 4, a P-type microcrystalline silicon film (μc-Si film), an I-type microcrystalline silicon film (μc-Si film), an N-type from the first power generation layer 3 side. The microcrystalline silicon films (μc-Si film) are sequentially formed (not shown).

  Then, a part of the first power generation layer 3, the intermediate layer 12, and the second power generation layer 4 thus laminated are substantially parallel to the short side direction of the insulating translucent substrate 1 as in the first embodiment. It is cut and removed into stripes in various directions, patterned into strips, and separated.

  Next, the back electrode layer 5 to be the second electrode layer is formed on the second power generation layer 4 by sputtering (FIGS. 5-5). As the back electrode layer 5, for example, a zinc oxide (ZnO) film having a thickness of 100 nm, a silver (Ag) film having a thickness of 100 nm, and an aluminum (Al) film having a thickness of 300 nm are formed from the second power generation layer 4 side.

  After the formation of the back electrode layer 5, a part of the back electrode layer 5 and the first power generation layer 3, the intermediate layer 12, and the second power generation layer 4 are arranged in the short direction of the insulating translucent substrate 1 in the same manner as in the first embodiment. Cut and removed into stripes in a substantially parallel direction, and patterned into strips to be separated into a plurality of cells C. As a result, the module 20 having the cell C as shown in FIG. 4A is formed.

With respect to the thin-film solar cell manufactured by the method for manufacturing a thin-film solar cell according to the second embodiment described above, AM (air mass) 1.5 light is emitted at a light amount of 100 mW / cm 2 using a solar simulator. Incident from the substrate side, the short-circuit current (mA / cm 2 ) was measured, and the characteristics as a solar cell were evaluated. As a result, the open circuit voltage is 1.35 V, the short-circuit current is 12.5 mA / cm 2 , the fill factor is 0.74, and the photoelectric conversion efficiency is 12.5%, and good output characteristics are obtained. confirmed.

  Further, in order to quantitatively examine the crystallinity of the μc-Si film layer, a P-type microcrystalline silicon film (μc-Si film), an I-type microcrystal is used as the second power generation layer 4 in the manufacturing process described above. When X-ray diffraction was performed on the silicon film (μc-Si film) formed, the ratio (220) X-ray diffraction peak integrated intensity I220 and (111) X-ray diffraction peak integrated intensity I111 was I220 / I111 4.0, and it was found that the μc-Si film layer was mainly composed of crystal grains grown in a columnar shape in a direction perpendicular to the substrate. By having such a structure, good carrier transport in the film thickness direction can be achieved by reducing defects in the crystalline semiconductor layer, and high photoelectric conversion efficiency can be obtained.

  According to the method for manufacturing a thin-film solar cell according to the second embodiment as described above, the surface of the transparent electrode layer 2 forms a concavo-convex shape having small convex portions 2a as a texture structure for light scattering. Light incident from the side of the insulating translucent substrate 1 is scattered at the interface between the transparent electrode layer 2 having the concavo-convex shape and the first power generation layer 3 and then enters the first power generation layer 3 to generate the first power generation. It is incident on the layer 3 substantially obliquely. Then, since light is incident on the first power generation layer 3 at an angle, a substantial optical path of the light is extended and the amount of light absorption in the power generation layer is increased, so that the photoelectric conversion characteristics of the thin film solar cell are improved and output. The current increases. Therefore, according to the method for manufacturing a thin film solar cell according to the second embodiment, a thin film solar cell having a good light diffusion effect and excellent in conversion efficiency can be produced.

  Moreover, according to the manufacturing method of the thin film solar cell concerning Embodiment 2 as mentioned above, in order to planarize the front-end | tip part of the convex part 12a of the intermediate | middle layer 12, and to relieve the uneven | corrugated shape of the intermediate | middle layer 12 surface, It is possible to suppress the influence of the irregular shape on the surface of the layer 12 on the crystal growth of the microcrystalline semiconductor film of the second power generation layer 4 and reduce structural defects in the microcrystalline semiconductor film due to the light scattering texture structure. it can. Thereby, a microcrystalline semiconductor film having a good film quality can be formed as the second power generation layer 4, and deterioration of carrier transport characteristics in the film thickness direction due to structural defects in the microcrystalline semiconductor film can be reduced.

  Even when the thickness of the first power generation layer 3 that is an amorphous silicon thin film is reduced, the microcrystalline silicon thin film of the second power generation layer 4 laminated on the intermediate layer 12 has a defect. Since it has a small film quality, it is easy to control the current value of the cell C by the film thickness of the first power generation layer 3 which is an amorphous silicon thin film, and a thin film solar cell with excellent controllability is produced. can do.

  Further, according to the method for manufacturing the thin-film solar cell according to the second embodiment, by providing the intermediate layer 12, a part of incident light is reflected by the intermediate layer 12 and is located on the light incident side with respect to the intermediate layer 12. Since the amount of light absorption in the first power generation layer 3 as the power generation layer increases, the current generated in the first power generation layer 3 can be increased. Since the optical confinement effect and the crystallinity of the amorphous silicon thin film photoelectric conversion layer are improved, the amorphous silicon thin film necessary for obtaining the same current value can be made thin. It becomes possible to suppress the characteristic deterioration of photoelectric conversion due to light degradation that becomes remarkable as the film thickness of the system thin film increases, and a highly reliable thin film solar cell can be manufactured.

  Therefore, according to the method for manufacturing the thin-film solar cell according to the second embodiment, the amount of light absorption in the photoelectric conversion layer due to the light confinement effect of the texture structure for light scattering and the film in the microcrystalline semiconductor thin-film photoelectric conversion layer are increased. A highly reliable thin film solar cell having high photoelectric conversion efficiency that achieves both good carrier transport characteristics in the thickness direction and high reliability can be manufactured.

  As described above, the thin film solar cell according to the present invention is useful for realizing high photoelectric conversion efficiency in a thin film solar cell using a microcrystalline semiconductor thin film as a photoelectric conversion layer.

It is a top view which shows schematic structure of the thin film solar cell concerning Embodiment 1, 2 of this invention. It is a figure for demonstrating the cross-section of the thin film solar cell concerning Embodiment 1 of this invention, and is principal part sectional drawing in line segment A-A 'of FIG. It is sectional drawing for demonstrating the shape of the transparent conductive film and 1st electric power generation layer in the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 1 of this invention. It is a figure for demonstrating the cross-sectional structure of the thin film solar cell concerning Embodiment 2 of this invention, and is principal part sectional drawing in line segment A-A 'of FIG. It is sectional drawing for demonstrating the shape of the transparent conductive film and 1st electric power generation layer in the thin film solar cell concerning Embodiment 2 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 2 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 2 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 2 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 2 of this invention. It is sectional drawing for demonstrating the manufacturing process of the thin film solar cell concerning Embodiment 2 of this invention.

Explanation of symbols

1 Insulating translucent substrate (glass substrate)
2 Transparent electrode layer 2a Convex portion 3 First power generation layer 3a Convex portion 4 Second power generation layer 5 Back electrode layer 6 P-type amorphous silicon carbide film (a-SiC film)
7 I-type amorphous silicon film (a-Si film)
8 N-type amorphous silicon film (a-Si film)
9 Coat film 10 Thin film solar cell module (module)
12 Intermediate layer 12a Convex portion 13 Buffer layer 14 Coat film 20 Thin film solar cell module (module)
23 1st power generation layer 23a Convex part C cell G1 1st groove | channel G2 2nd groove | channel G3 3rd groove | channel

Claims (12)

  1. On the insulating translucent substrate, a first electrode layer made of a transparent conductive film, a first power generation layer made of an amorphous semiconductor film for photoelectric conversion, and a second power generation made of a microcrystalline semiconductor film for photoelectric conversion. A thin film solar cell in which a layer and a second electrode layer made of a conductive film that reflects light are laminated in this order,
    The first electrode layer has an uneven shape on the surface on the first power generation layer side,
    The first power generation layer has a concavo-convex shape on the second power generation layer side corresponding to the concavo-convex shape of the first electrode layer, and an upper surface of the convex portion is substantially in-plane direction of the insulating light-transmitting substrate. Be parallel surfaces,
    A thin film solar cell characterized by
  2. The microcrystalline semiconductor film constituting the second power generation layer is mainly composed of crystal grains grown in a columnar shape in a direction perpendicular to the insulating light-transmitting substrate;
    The thin film solar cell according to claim 1.
  3. On the insulating translucent substrate, a first electrode layer made of a transparent conductive film, a first power generation layer made of an amorphous semiconductor film for performing photoelectric conversion, an intermediate layer made of a transparent conductive film, and a microcrystalline semiconductor film A thin-film solar cell in which a second power generation layer made of photoelectric conversion and a second electrode layer made of a conductive film that reflects light are laminated in this order,
    The first electrode layer has an uneven shape on the surface on the first power generation layer side,
    The first power generation layer has an uneven shape corresponding to the uneven shape of the first electrode layer,
    The intermediate layer has a concavo-convex shape on the second power generation layer side corresponding to the concavo-convex shape of the first power generation layer, and the upper surface of the convex portion is substantially parallel to the in-plane direction of the insulating light-transmitting substrate. That it is a surface,
    A thin film solar cell characterized by
  4. The microcrystalline semiconductor film constituting the second power generation layer is mainly composed of crystal grains grown in a columnar shape in a direction perpendicular to the insulating light-transmitting substrate;
    The thin film solar cell according to claim 3.
  5. On the insulating translucent substrate, a first electrode layer made of a transparent conductive film, a first power generation layer made of an amorphous semiconductor film for photoelectric conversion, and a second power generation made of a microcrystalline semiconductor film for photoelectric conversion. A method of manufacturing a thin-film solar cell in which a layer and a second electrode layer made of a conductive film that reflects light are laminated in this order,
    Forming a first electrode layer having a concavo-convex shape on a surface thereof on the insulating light-transmitting substrate;
    A second step of forming the first power generation layer in a concavo-convex shape corresponding to the surface concavo-convex shape of the first electrode layer on the first electrode layer;
    A third step of forming a sacrificial film on the first power generation layer;
    A fourth step of etching back the sacrificial film and the first power generation layer to expose the concavo-convex convex portion on the surface of the first power generation layer and flattening the tip of the convex portion;
    A fifth step of removing the sacrificial film;
    A sixth step of forming the second power generation layer on the first power generation layer;
    A seventh step of forming the second electrode layer on the second power generation layer;
    The manufacturing method of the thin film solar cell characterized by including.
  6. The sacrificial film is made of resist or acrylic resin,
    In the fourth step, the reaction is performed under the condition that the etching selectivity of the first power generation layer with respect to the sacrificial film is 1 or more using a halogen-based gas or an etching gas in which an oxygen gas or a helium gas is mixed with the halogen-based gas. Etching back by reactive ion etching,
    The manufacturing method of the thin film solar cell of Claim 5 characterized by these.
  7. The sacrificial film has a film thickness dimension that is at least one times the average height dimension of the concavo-convex protrusions in the first power generation layer,
    The manufacturing method of the thin film solar cell of Claim 5 characterized by these.
  8. Forming, as the second power generation layer, a microcrystalline semiconductor film mainly composed of crystal grains grown in a columnar shape in a direction perpendicular to the insulating light-transmitting substrate;
    The manufacturing method of the thin film solar cell of Claim 5 characterized by these.
  9. On the insulating translucent substrate, a first electrode layer made of a transparent conductive film, a first power generation layer made of an amorphous semiconductor film for performing photoelectric conversion, an intermediate layer made of a transparent conductive film, and a microcrystalline semiconductor film A method of manufacturing a thin-film solar cell in which a second power generation layer that performs photoelectric conversion and a second electrode layer that includes a conductive film that reflects light are stacked in this order,
    A first step of forming the first electrode layer having a concavo-convex shape on the insulating translucent substrate;
    A second step of forming the first power generation layer in a concavo-convex shape corresponding to the surface concavo-convex shape of the first electrode layer on the first electrode layer;
    A third step of forming the intermediate layer in a concavo-convex shape corresponding to the surface concavo-convex shape of the first power generation layer on the first power generation layer;
    A fourth step of forming a sacrificial film on the intermediate layer;
    Etching back the sacrificial film and the intermediate layer to expose the concavo-convex convex portion on the surface of the intermediate layer and flatten the tip of the convex portion;
    A sixth step of removing the sacrificial film;
    A seventh step of forming the second power generation layer on the intermediate layer;
    An eighth step of forming the second electrode layer on the second power generation layer;
    The manufacturing method of the thin film solar cell characterized by including.
  10. The sacrificial film is made of resist or acrylic resin,
    In the fifth step, a reactive ion is used under the condition that the etching selectivity of the intermediate layer with respect to the sacrificial film is 1 or more using a halogen-based gas or an etching gas obtained by mixing an oxygen gas or a helium gas with the halogen-based gas. Etching back by etching,
    The method for producing a thin-film solar cell according to claim 9.
  11. The sacrificial film has a film thickness dimension that is at least one times the average height dimension of the concavo-convex protrusions in the intermediate layer,
    The method for producing a thin-film solar cell according to claim 9.
  12. Forming, as the second power generation layer, a microcrystalline semiconductor film mainly composed of crystal grains grown in a columnar shape in a direction perpendicular to the insulating light-transmitting substrate;
    The method for producing a thin-film solar cell according to claim 9.
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