JP2011135021A - Thin-film solar cell, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-film solar cell capable of effective utilization of light and excelling in photoelectric conversion efficiency, and to provide a method of manufacturing the same. <P>SOLUTION: This thin-film solar cell includes, on a translucent substrate 1, a first electrode layer 2 formed of a transparent conductive film, a first photoelectric conversion layer 3 for performing photoelectric conversion, an intermediate layer 4, a second photoelectric conversion layer 5 for performing photoelectric conversion, a second electrode layer 7 in this order. In the thin-film solar cell, a first texture structure 2a having a plurality of irregularities is formed on a light incident side of the first photoelectric conversion layer 3; a second texture structure 4a having a plurality of irregularities is formed on the light incident side of the second photoelectric conversion layer 5 and between the first photoelectric conversion layer 3 and the second photoelectric conversion layer 5; the formation interval P1 of the irregularities in the first texture structure 2a is shorter than the wavelength of light used for photoelectric conversion in the second photoelectric conversion layer 5; and the formation interval P2 of the irregularities in the second texture structure 4a is longer than the formation interval P1 of the irregularities in the first texture structure 2a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin film solar cell having a plurality of photoelectric conversion element layers and a method for producing the same.

  In conventional laminated thin-film solar cells, a textured structure with an appropriate concavo-convex shape is formed on the surface of a transparent conductive film to form a film on a substrate, and a plurality of photoelectric conversion layers are laminated thereon, and these are electrically connected in series. ing. Then, by laminating a plurality of photoelectric conversion layers having different semiconductor band gaps, it is possible to absorb light having a wide wavelength from a short wavelength to a long wavelength of incident sunlight.

  Usually, a photoelectric conversion layer that absorbs light in the short wavelength region is arranged on the light incident side, and a photoelectric conversion layer that absorbs light in the high wavelength region is arranged on the back electrode side, and incident sunlight is absorbed in order from the short wavelength. To go. At this time, the incident sunlight is refracted by the difference in refractive index between the transparent conductive film and the photoelectric conversion layer and the unevenness formed on the surface of the transparent conductive film. Thereby, the power generation efficiency of the stacked thin-film solar cell is increased by increasing the optical path length in the photoelectric conversion layer.

  In the laminated thin-film solar cell, the first photoelectric conversion layer, the intermediate layer, and the second photoelectric conversion layer are formed on the transparent conductive film, so that the surface of the first photoelectric conversion layer, the intermediate layer, and the second photoelectric conversion layer is formed. The irregularities formed have the same period as the irregularities formed on the surface of the transparent conductive film, but the level difference is dull. For this reason, when sunlight infiltrates from the intermediate film to the second photoelectric conversion layer, states such as insufficient refraction of sunlight and reflection occur.

  Therefore, in the stacked photoelectric conversion element in which light enters from the second photoelectric conversion layer side, at least two photoelectric conversion element layers and at least one layer sandwiched between the first electrode layer and the second electrode layer on the light incident side are provided. In the stacked photoelectric conversion element composed of the intermediate layer, the intermediate layer sandwiched between the photoelectric conversion element layers and the photoelectric conversion element layer adjacent to the first electrode side of the intermediate layer have irregularities on their respective surfaces on the light incident side. And the photoelectric conversion element layer has irregularities having an average height difference larger than that of the intermediate layer, thereby suppressing light used in the second photoelectric conversion layer from being reflected at the interface between the first photoelectric conversion layer and the intermediate layer. And the technique which raises the photoelectric conversion efficiency in a 2nd photoelectric converting layer is disclosed (for example, refer patent document 1).

JP 2003-69061 A

  However, according to the conventional technique, an antireflection effect can be expected by changing the average height difference between the first photoelectric conversion layer and the second photoelectric conversion layer. When the irregularity formation interval (period) of the photoelectric conversion layer is the same, depending on the irregularity formation interval, not only sunlight having a wavelength used for photoelectric conversion in the first photoelectric conversion layer but also photoelectric conversion in the second photoelectric conversion layer Sunlight having a wavelength to be used is also refracted, and the optical path length of sunlight having a wavelength used for photoelectric conversion in the second photoelectric conversion layer becomes longer in the first photoelectric conversion layer, causing loss.

  Moreover, the sunlight of the wavelength used for photoelectric conversion in a 2nd photoelectric conversion layer permeate | transmits the formation interval of the unevenness | corrugation of a 1st photoelectric conversion layer, and the sunlight of the wavelength used for photoelectric conversion in a 1st photoelectric conversion layer refracts | refracts. If it sets in this way, the formation interval of the unevenness | corrugation of an intermediate | middle layer and a 2nd photoelectric converting layer will also become the same. For this reason, also in the 2nd photoelectric conversion layer, since the sunlight of the wavelength used for photoelectric conversion permeate | transmits without being refracted, an optical path length becomes short and photoelectric conversion efficiency falls. That is, no consideration is given to the formation interval of the texture structure irregularities in the first photoelectric conversion layer and the second photoelectric conversion layer.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the thin film solar cell excellent in photoelectric conversion efficiency which can use light effectively, 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 a first photoelectric conversion layer that performs photoelectric conversion on a translucent substrate. A thin-film solar cell having an intermediate layer, a second photoelectric conversion layer that performs photoelectric conversion, and a second electrode layer in this order, and having a plurality of irregularities on the light incident side of the first photoelectric conversion layer A second texture structure formed of a plurality of irregularities on the light incident side of the second photoelectric conversion layer and between the first photoelectric conversion layer and the second photoelectric conversion layer. And the formation interval of the unevenness in the first texture structure is shorter than the wavelength of light used for photoelectric conversion in the second photoelectric conversion layer, and the formation interval of the unevenness in the second texture structure is the first Formation of the unevenness in the texture structure of 1 Longer than interval, characterized by.

  According to the present invention, each photoelectric conversion layer contributes to photoelectric conversion by changing the unevenness formation interval in the texture on the light incident side of each photoelectric conversion layer according to the wavelength of light used for photoelectric conversion by each photoelectric conversion layer. As a result, the optical path length of sunlight having a longer wavelength is increased, the photoelectric conversion efficiency is improved, and a laminated thin film solar cell excellent in photoelectric conversion efficiency capable of effectively using sunlight is obtained.

FIG. 1 is a cross-sectional view schematically showing a configuration of a stacked thin-film solar battery that is a thin-film solar battery according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the relationship between sunlight transmission and scattering in the stacked thin-film solar cell according to the first embodiment of the present invention. FIGS. 3-1 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 1 of this invention. FIGS. 3-2 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 1 of this invention. FIGS. 3-3 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 1 of this invention. FIGS. 3-4 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 1 of this invention. 3-5 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 1 of this invention. FIG. 4 is a cross-sectional view schematically showing a configuration of a stacked thin-film solar cell that is a thin-film solar cell according to the second embodiment of the present invention. FIG. 5 is a schematic diagram showing the relationship between the transmission and scattering of sunlight in the stacked thin film solar cell according to the second embodiment of the present invention. FIG. 6-1 is a cross-sectional view for explaining the method for manufacturing the stacked thin-film solar cell according to the second embodiment of the present invention. 6-2 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 2 of this invention. 6-3 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 2 of this invention. 6-4 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 2 of this invention. 6-5 is sectional drawing for demonstrating the manufacturing method of the lamination type thin film solar cell concerning Embodiment 2 of this invention.

  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 cross-sectional view schematically showing the configuration of a stacked thin-film solar battery that is a thin-film solar battery according to Embodiment 1 of the present invention. As shown in FIG. 1, the laminated thin film solar cell according to the present embodiment includes a translucent substrate 1, a front transparent electrode layer 2 formed on the translucent substrate 1 and serving as a first electrode layer, and a front transparent electrode. A first photoelectric conversion layer 3 which is a first thin film semiconductor layer formed on the layer 2, an intermediate layer 4 formed on the first photoelectric conversion layer 3, and a second thin film semiconductor formed on the intermediate layer 4. The second photoelectric conversion layer 5, which is a layer, the back transparent conductive film 6 formed on the second photoelectric conversion layer 5, and the back electrode layer 7 serving as the second electrode layer formed on the back transparent conductive film 6 are sequentially formed. It has a laminated structure. In this laminated thin film solar cell, the light transmitting substrate 1 side is the light incident side on which sunlight 50 is incident.

  As the light-transmitting substrate 1, a light-transmitting resin having heat resistance such as glass, polyimide, or polyvinyl, or a laminate of these can be used as appropriate. There is no particular limitation as long as it can be structurally supported. Alternatively, a highly permeable metal film, transparent conductive film, or insulating film may be formed on these surfaces.

The front transparent electrode layer 2 is made of a translucent conductive material, and a transparent conductive film such as tin oxide (SnO ₂ ), zinc oxide (ZnO), or ITO can be used. A small amount of impurities may be added to the film of the front transparent electrode layer 2. For example, when zinc oxide (ZnO) is the main component, a Group IIIB element such as gallium (Ga), aluminum (Al), or boron (B) of about 5 × 10 ^{20 to} 5 × 10 ²¹ cm ⁻³ , or Since the resistivity is reduced by containing a Group IV element such as copper (Cu), it is suitable for use as an electrode. The front transparent electrode layer 2 is manufactured by sputtering, atmospheric pressure CVD (Chemical Vapor Deposition), low pressure CVD, MOCVD (Metal Organic Chemical Vapor Deposition), electron beam evaporation, sol-gel method, electrodeposition, spraying. It can produce by well-known methods, such as.

  Further, on the surface of the front transparent electrode layer 2 on the first photoelectric conversion layer 3 side (an interface between the front transparent electrode layer 2 and the first photoelectric conversion layer 3), a texture structure 2a for light scattering (hereinafter referred to as texture 2a) Concavities and convexities are formed. The unevenness of the light scattering texture 2a is periodically formed at a predetermined unevenness formation interval P1 in the in-plane direction of the front transparent electrode layer 2. And the uneven | corrugated formation space | interval P1 is made shorter than the wavelength of the light used for the photoelectric conversion in the 2nd photoelectric converting layer 5. FIG.

  Here, the height of the unevenness of the light scattering texture 2a is the average height difference of the unevenness. Moreover, the uneven | corrugated formation space | interval P1 of the texture 2a for light scattering is the distance (or bottom part position of an adjacent recessed part) in the in-plane direction of the front transparent electrode layer 2 in the unevenness | corrugation of the texture 2a. Distance). This texture causes light scattering and refraction, and provides a light confinement effect in the photoelectric conversion layer below the front conductive film, thereby improving the short-circuit current density. The aspect ratio (height / unevenness formation interval P1) between the unevenness height of the light scattering texture 2a and the unevenness formation interval P1 is preferably in the range of 1 to 1/4.

The method of forming this texture is not particularly limited, but it can be formed by performing dry etching or wet etching on the surface of the translucent substrate 1 or the front transparent electrode layer 2. In dry etching, for example, an etching gas can be ionized or radicalized by plasma discharge and irradiated, and physical or chemical etching can be performed to form irregularities. In the physical etching, an inert gas such as argon (Ar) is used as an etching gas. In chemical etching, for example, fluorine gas such as tetrafluoromethane (CF ₄ ), hexafluoroethane (C ₂ F ₆ ), chlorine gas such as carbon tetrachloride (CCl ₄ ), four as etching gases. Silicon chloride (SiCl ₄ ) or the like is used.

  As the wet etching, a method of immersing the translucent substrate 1 or the front transparent electrode layer 2 in an acid or alkaline solution can be used. In this case, examples of the acid solution that can be used include one kind or a mixture of two or more kinds of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, acetic acid, formic acid, perchloric acid, and the like.

  Moreover, texture formation is also possible by performing machining such as sandblasting. Furthermore, without using the etching method as described above, a method of using surface irregularities formed by crystal growth of a transparent conductive film material as a texture when depositing a transparent conductive film by a CVD method, and transparent by a sol-gel method or a spray method A method of using unevenness depending on the crystal grain size at the time of forming the conductive film as a texture can be used.

  As a photoelectric converting layer, the 1st photoelectric converting layer 3 and the 2nd photoelectric converting layer 5 are arrange | positioned in order from the light-receiving surface side (translucent substrate 1). The film thicknesses of the first photoelectric conversion layer 3 and the second photoelectric conversion layer 5 are preferably about 500 nm to 1000 nm, for example. In this embodiment, an example in which two photoelectric conversion layers of the first photoelectric conversion layer 3 and the second photoelectric conversion layer 5 are provided as the photoelectric conversion layer is shown. However, in the present invention, the number of stacked photoelectric conversion layers is shown. Is not limited to two, and may have a configuration in which two or more layers are stacked, and may have a configuration in which an intermediate layer is sandwiched between at least two photoelectric conversion layers. In this case, the photoelectric conversion layer is formed by laminating a plurality of photoelectric conversion layers in the order of the first photoelectric conversion layer, the second photoelectric conversion layer, the third photoelectric conversion layer, etc. in order from the light receiving surface side. An intermediate layer is sandwiched between the conversion layers.

  The photoelectric conversion layer in the stacked thin film solar cell is a semiconductor photoelectric conversion layer regardless of silicon type or compound type, for example, a pin having a p-type semiconductor layer, an i-type (intrinsic) semiconductor layer, and an n-type semiconductor layer. It is constituted by a junction structure or a PN junction between a p-type semiconductor layer and an n-type semiconductor layer. In the first photoelectric conversion layer 3, for example, a p-type semiconductor layer, an i-type (intrinsic) semiconductor layer, and an n-type semiconductor layer (not shown) are sequentially stacked from the light receiving surface side. In the second photoelectric conversion layer 5, for example, a p-type semiconductor layer, an i-type (intrinsic) semiconductor layer, and an n-type semiconductor layer (not shown) are sequentially stacked from the light receiving surface side. The intrinsic semiconductor layer may exhibit weak p-type and n-type conductivity as long as the photoelectric conversion function is not impaired.

Here, the semiconductor photoelectric conversion layer is amorphous silicon oxide (a-SiO), amorphous silicon carbide (a-SiC), amorphous silicon (a-Si), amorphous silicon germanium (a-SiGe), or silicon (Si) nanodot. The main component is silicon, such as microcrystalline silicon (μc-Si) or nanocrystalline silicon (nc-Si), or compound such as CIGS (Cu (InGa) Se ₂ ) or germanium (Ge). It means a photoelectric conversion layer made of a base material and formed of three semiconductor layers constituting a pin structure by adding an acceptor or donor suitable for each semiconductor to form p-type or n-type. As these manufacturing methods, the CVD method is common. Examples of the CVD method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD, thermal CVD, hot wire CVD, and MOCVD.

  The first photoelectric conversion layer 3 is a photoelectric conversion layer that mainly absorbs light in a short wavelength region and performs photoelectric conversion, and is made of, for example, an amorphous silicon (a-Si) material having a short absorption wavelength region of sunlight. It is preferable. Examples of such a semiconductor photoelectric conversion layer include amorphous silicon oxide (a-SiO), amorphous silicon carbide (a-SiC), amorphous silicon (a-Si), and the like. In the present embodiment, a case where amorphous silicon (a-Si) is used for the first photoelectric conversion layer 3 will be described.

  The second photoelectric conversion layer 5 is a photoelectric conversion layer that performs photoelectric conversion mainly by absorbing light in a higher wavelength region than the first photoelectric conversion layer 3, for example, amorphous silicon having a long absorption wavelength region for absorbing sunlight. Examples thereof include germanium (a-SiGe). In the present embodiment, a case where silicon germanium (SiGe) is used for the second photoelectric conversion layer 5 will be described.

  In addition, when laminating a plurality of three or more photoelectric conversion layers, the photoelectric conversion layer is in the order of the first photoelectric conversion layer, the second photoelectric conversion layer, the third photoelectric conversion layer, ... from the light receiving surface side. A plurality of photoelectric conversion layers are stacked, and an intermediate layer is sandwiched between at least two photoelectric conversion layers. And the wavelength range of the light to absorb becomes long in order of a 1st photoelectric converting layer, a 2nd photoelectric converting layer, a 3rd photoelectric converting layer ....

The intermediate layer 4 is sandwiched between the adjacent first photoelectric conversion layer 3 and the second photoelectric conversion layer 5, has a refractive index different from that of the first photoelectric conversion layer 3, has high conductivity, and has little light absorption. For example, it is preferably made of conductive oxide, doped silicon oxide (SiO _x ), doped (SiN _x ), or the like. Moreover, the film thickness of the intermediate layer 4 is preferably about 80 nm to 200 nm, for example. In the present embodiment, doped silicon oxide (SiO _x ) is used for the intermediate layer 4.

  By providing the adjacent intermediate layer 4 having a refractive index different from that of the first photoelectric conversion layer 3, the light reflection at the interface is increased, and the amount of light reflected to the first photoelectric conversion layer 3 is increased to increase the first photoelectric conversion layer 3. The photocurrent generated in the conversion layer 3 can be increased. At this time, when the refractive index of silicon oxide in the intermediate layer 4 is smaller than the refractive index of the first photoelectric conversion layer 3, the light reflection to the first photoelectric conversion layer 3 can be increased.

  Moreover, the light absorption coefficient of the intermediate layer 4 is preferably as small as possible, and more preferably no light absorption. This is because the light that has not been absorbed by the intermediate layer 4 reaches the second photoelectric conversion layer 5 and is effectively used to generate a photocurrent in the second photoelectric conversion layer 5.

  Further, the surface of the intermediate layer 4 on the second photoelectric conversion layer 5 side (interface between the intermediate layer 4 and the second photoelectric conversion layer 5) has unevenness as a texture structure 4a for light scattering (hereinafter referred to as texture 4a). Is formed. The unevenness of the light scattering texture 4 a is formed at a predetermined unevenness formation interval P <b> 2 in the in-plane direction of the intermediate layer 4. And the uneven | corrugated formation space | interval P2 is made longer than the uneven | corrugated formation space | interval P1 of the texture 2a.

  Here, the height of the unevenness of the light scattering texture 4a is the average height difference of the unevenness. Moreover, the uneven | corrugated formation space | interval P2 of the texture 4a for light scattering is the distance (or adjacent) between the vertex positions of the adjacent convex part in the in-plane direction of the front transparent electrode layer 2 in the unevenness | corrugation of the light scattering texture 4a. Distance between the bottom positions of the recesses). This texture causes light scattering and refraction, and provides a light confinement effect in the photoelectric conversion layer below the front conductive film, thereby improving the short-circuit current density. The aspect ratio (height / unevenness formation interval P2) between the unevenness height of the light scattering texture 4a and the unevenness formation interval P2 is preferably in the range of 1 to 1/4.

  A method for forming this texture is not particularly limited, but the texture can be formed by subjecting the surface of the intermediate layer 4 to dry etching or wet etching. For example, after forming the intermediate layer 4, a resist is applied in a pattern with an arbitrary interval (P 2), and the surface of the intermediate layer 4 is wet-etched using this as a mask to form irregularities on the surface of the intermediate layer 4. Thus, a light scattering texture can be formed. Further, after the intermediate layer 4 is formed, the surface of the intermediate layer 4 is dry-etched using a dry etching mask having a pattern with an arbitrary interval (P2), thereby forming irregularities on the surface of the intermediate layer 4. Thus, the light scattering texture 4a can be formed.

The back transparent conductive film 6 is made of a translucent conductive material, and a transparent conductive film such as tin oxide (SnO ₂ ), zinc oxide (ZnO), or ITO can be used. A small amount of impurities may be added to the film of the back transparent conductive film 6. For example, when zinc oxide (ZnO) is the main component, a predetermined amount of a group IIIB element such as gallium (Ga), aluminum (Al) or boron (B), or a group IV element such as copper (Cu) Since the resistivity is reduced by containing, it is suitable for use as an electrode. The manufacturing method of the back surface transparent conductive film 6 can be produced by a known method such as a sputtering method, an atmospheric pressure CVD method, a low pressure CVD method, an MOCVD method, an electron beam evaporation method, a sol-gel method, an electrodeposition method, or a spray method.

  The back electrode layer 7 functions as a back electrode and also functions as a reflective layer that reflects light that has not been absorbed by the photoelectric conversion layer and returns it to the photoelectric conversion layer, thereby contributing to improvement in photoelectric conversion efficiency. Therefore, the back electrode layer 7 is more preferable as the light reflectance is higher and the conductivity is higher. The back electrode layer 7 is made of a metal material such as silver (Ag), aluminum (Al), titanium (Ti) or palladium having a high visible light reflectance, or an alloy of these metal materials, a nitride of these metal materials, These metal materials can be used to form oxides. In addition, the specific material of these back surface electrode layers 7 is not specifically limited, It can select from a well-known material suitably and can be used.

  FIG. 2 is a schematic diagram showing the relationship between the transmission and scattering of sunlight in the stacked thin-film solar cell according to the first embodiment configured as described above. In the first photoelectric conversion layer 3 made of amorphous silicon (a-Si), sunlight 51 having a wavelength of about 350 nm to 600 nm is used for photoelectric conversion, and particularly, the photoelectric conversion efficiency of the sunlight 51 having a wavelength near about 500 nm is high. . Therefore, in the stacked thin film solar cell according to the first embodiment, the first photoelectric conversion layer in the front transparent electrode layer 2 is used to refract sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3 with the texture 2a. The unevenness formation interval P1 of the light scattering texture 2a formed at the interface on the 3 side is in the range of the same level to 1/2 of the wavelength of sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3, that is, 250 nm to It is set to 500 nm.

  By providing the texture 2a having such a periodic structure, the sunlight 51 (sunlight having a wavelength of approximately 350 nm to 600 nm) used for photoelectric conversion in the first photoelectric conversion layer 3 is the interface of the texture 2a, that is, the first The light is refracted at the light incident side interface in the photoelectric conversion layer 3 and enters the first photoelectric conversion layer 3. Thereby, the optical path length of the sunlight 51 in the 1st photoelectric converting layer 3 becomes long, and a photoelectric conversion efficiency can be improved. In order to prevent reflection of the sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3 in the texture 2a, the unevenness formation interval P1 of the texture 2a is preferably about 250 nm to 350 nm.

  Moreover, since the sunlight 52 (sunlight having a wavelength of about 500 nm to 900 nm) used for photoelectric conversion in the second photoelectric conversion layer 5 has a longer wavelength than the light used in the first photoelectric conversion layer 3, the interface of the texture 2a. The light is incident on the first photoelectric conversion layer 3 without bending. Thereby, the optical path length of the sunlight 52 in the 1st photoelectric converting layer 3 can be shortened, the absorption loss of the sunlight 52 in a 1st photoelectric converting layer can be reduced, and a photoelectric conversion efficiency can be improved.

  On the other hand, in the second photoelectric conversion layer 5 made of silicon germanium (a-SiGe), sunlight having a wavelength of about 500 nm to 900 nm is used for photoelectric conversion, and in particular, the photoelectric conversion efficiency of the sunlight 51 having a wavelength near about 700 nm is used. high. Therefore, in the stacked thin film solar cell according to the first embodiment, the second photoelectric conversion layer 5 side in the intermediate layer 4 is used to refract the sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 with the texture 4a. The unevenness formation interval P2 of the light scattering texture 4a formed on the interface of the second photoelectric conversion layer 5 is in the range of the same level to 1/2 of the wavelength of sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5, that is, 350 nm to 700 nm. It is set.

  By providing the texture 4a having such a periodic structure, sunlight 52 (sunlight having a wavelength of approximately 500 nm to 900 nm) used for photoelectric conversion in the second photoelectric conversion layer 5 is the interface of the texture 4a, that is, the second The photoelectric conversion layer 5 is refracted at the interface between the intermediate layer 4 on the light incident side and the second photoelectric conversion layer 5 and enters the second photoelectric conversion layer 5. Thereby, the optical path length of the sunlight 52 in the 2nd photoelectric converting layer 5 becomes long, and a photoelectric conversion efficiency can be improved. In order to prevent reflection of sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 in the texture 4a, the unevenness formation interval P2 of the texture 4a is preferably about 350 nm to 600 nm.

  As described above, in the stacked thin film solar cell according to the first embodiment, the surface on the light incident side of the first photoelectric conversion layer 3 and the first photoelectric conversion layer 3 side in the front transparent electrode layer 2 (front transparent) The light scattering texture 2a formed on the electrode layer 2 and the first photoelectric conversion layer 3) and the light incident side of the second photoelectric conversion layer 5 and the second photoelectric conversion layer 5 side of the intermediate layer 4 The light scattering texture 4a formed on the surface (interface between the intermediate layer 4 and the second photoelectric conversion layer 5). And the uneven | corrugated formation space | interval P1 of the texture 2a is shorter than the wavelength of the sunlight 52 used for photoelectric conversion in the 2nd photoelectric converting layer 5, and the uneven | corrugated space | interval P2 of the texture 4a is longer than the uneven | corrugated space | interval P1 of the texture 2a. Is set.

  By having such a configuration, light (sunlight 51) having a wavelength used for photoelectric conversion in the first photoelectric conversion layer 3 among the incident sunlight is texture on the light incident side of the first photoelectric conversion layer 3. Since the light is refracted by 2a and is incident on the first photoelectric conversion layer 3 from an oblique direction, the optical path length is increased and the power generation efficiency is increased. Moreover, since the wavelength of light (sunlight 52) used for the photoelectric conversion in the second photoelectric conversion layer 5 is longer than the light used for the photoelectric conversion in the first photoelectric conversion layer 3, the first photoelectric conversion layer 3 The light incident side texture 2a is transmitted without being refracted, and the optical path when passing through the first photoelectric conversion layer 3 is the shortest, so that absorption loss in the first photoelectric conversion layer 3 can be prevented. Furthermore, the unevenness formation interval P2 of the texture 4a on the light incident side of the second photoelectric conversion layer 5 is made longer than the unevenness formation interval P1 of the texture 2a on the light incident side of the first photoelectric conversion layer 3, thereby making the second photoelectric conversion layer 5 Since the light used for photoelectric conversion is refracted and incident obliquely on the second photoelectric conversion layer, the optical path length in the second photoelectric conversion layer 5 is increased, and the photoelectric conversion efficiency is improved.

  Therefore, according to the laminated thin film solar cell according to the first embodiment, the unevenness formation interval in the texture on the light incident side of each photoelectric conversion layer is changed in accordance with the wavelength of light used by each photoelectric conversion layer for photoelectric conversion. As a result, the optical path length of sunlight having a wavelength that contributes to photoelectric conversion in each photoelectric conversion layer is increased, the photoelectric conversion efficiency is improved, and the stacked thin film solar cell excellent in photoelectric conversion efficiency that can effectively use sunlight is obtained. It has been realized.

  Next, a method for manufacturing the stacked thin film solar cell according to the present embodiment configured as described above will be described with reference to FIGS. 3-1 to 3-5 are cross-sectional views for explaining the method for manufacturing the stacked thin-film solar cell according to the first embodiment.

  First, the translucent substrate 1 is prepared. Here, for example, a flat white glass plate is used as the translucent substrate 1. A front transparent electrode layer 2 is formed on the translucent substrate 1 by a known method. For example, the front transparent electrode layer 2 made of a zinc oxide (ZnO) film is formed on the translucent substrate 1 by a sputtering method. Further, as a film formation method, another film formation method such as a CVD method may be used. Then, for example, asperity is formed on the surface of the front transparent electrode layer 2 as a light scattering texture 2a by a predetermined etching interval P1 (FIG. 3A).

  Next, the first photoelectric conversion layer 3 is formed on the front transparent electrode layer 2 by a known method (FIG. 3-2). For example, a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer (not shown) made of amorphous silicon (a-Si) are sequentially stacked on the front transparent electrode layer 2 by plasma CVD as the first photoelectric conversion layer 3. . The surface of the first photoelectric conversion layer 3 has an uneven shape equivalent to the surface of the front transparent electrode layer 2.

Next, the intermediate layer 4 is formed on the entire surface of the first photoelectric conversion layer 3 by a known method. For example, a doped silicon oxide (SiO _x ) film is formed on the first photoelectric conversion layer 3 by the plasma CVD method as the intermediate layer 4. At this time, the surface of the intermediate layer 4 has an uneven shape equivalent to the surface of the first photoelectric conversion layer 3, that is, an uneven shape equivalent to the surface of the front transparent electrode layer 2, and the surface unevenness of the intermediate layer 4 is The gaps between the front transparent electrode layers 2 are the same as those of the front transparent electrode layer 2.

  Subsequently, unevenness is periodically formed on the surface of the intermediate layer 4 as a light scattering texture 4a at a predetermined unevenness formation interval P2 by wet etching, for example. Thereby, the intermediate | middle layer 4 which has the texture 4a formed in the predetermined | prescribed uneven | corrugated formation space | interval P2 different from the texture 2a on the surface is obtained (FIG. 3-3).

  Next, the second photoelectric conversion layer 5 is formed on the intermediate layer 4 by a known method (FIGS. 3-4). For example, a p-type semiconductor layer, i-type semiconductor layer, and n-type semiconductor layer (not shown) made of silicon germanium (SiGe) are sequentially stacked on the intermediate layer 4 by the plasma CVD method as the second photoelectric conversion layer 5.

  Next, the back surface transparent conductive film 6 is formed on the second photoelectric conversion layer 5 by a known method. For example, the back transparent conductive film 6 made of a zinc oxide (ZnO) film is formed on the second photoelectric conversion layer 5 by a sputtering method. Further, as a film formation method, another film formation method such as a CVD method may be used.

  Subsequently, the back electrode layer 7 is formed on the back transparent conductive film 6 by a known method. For example, the back electrode layer 7 made of a silver (Ag) film having a high reflectance is formed on the back transparent conductive film 6 by a sputtering method (FIGS. 3-5). Through the above processing, the stacked thin film solar cell according to the present embodiment shown in FIG. 1 is obtained.

  As described above, in the method for manufacturing the stacked thin film solar cell according to the first embodiment, the surface on the light incident side of the first photoelectric conversion layer 3 and on the first photoelectric conversion layer 3 side in the front transparent electrode layer 2. Light scattering is performed so that the unevenness formation interval P1 is shorter than the wavelength of sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 (at the interface between the front transparent electrode layer 2 and the first photoelectric conversion layer 3). The texture 2a is formed. And the uneven | corrugated formation space | interval P2 is the light incident side of the 2nd photoelectric converting layer 5, and the surface (interface of the intermediate | middle layer 4 and the 2nd photoelectric converting layer 5) by the side of the 2nd photoelectric converting layer 5 in the intermediate | middle layer 4. The light scattering texture 4a is formed so as to be longer than the unevenness formation interval P1 of the texture 2a.

  By forming such a light scattering texture 2a and texture 4a, light of the wavelength used for photoelectric conversion in the first photoelectric conversion layer 3 (sunlight 51) among the incident sunlight is the first photoelectric. The light is refracted by the texture 2a on the light incident side of the conversion layer 3 and is incident on the first photoelectric conversion layer 3 at an angle, so that the optical path length is increased and the power generation efficiency is increased. Moreover, since the wavelength of light (sunlight 52) used for the photoelectric conversion in the second photoelectric conversion layer 5 is longer than the light used for the photoelectric conversion in the first photoelectric conversion layer 3, the first photoelectric conversion layer 3 The light incident side texture 2a is transmitted without being refracted, and the optical path when passing through the first photoelectric conversion layer 3 is the shortest, so that absorption loss in the first photoelectric conversion layer 3 can be prevented. Furthermore, the unevenness formation interval P2 of the texture 4a on the light incident side of the second photoelectric conversion layer 5 is made longer than the unevenness formation interval P1 of the texture 2a on the light incident side of the first photoelectric conversion layer 3, thereby making the second photoelectric conversion layer 5 Since the light used for photoelectric conversion is refracted and incident obliquely on the second photoelectric conversion layer, the optical path length in the second photoelectric conversion layer 5 is increased, and the photoelectric conversion efficiency is improved.

  Therefore, according to the manufacturing method of the stacked thin-film solar cell according to the first embodiment, the unevenness formation interval in the texture on the light incident side of each photoelectric conversion layer is set in accordance with the wavelength of light that each photoelectric conversion layer uses for photoelectric conversion. By changing the length, the optical path length of sunlight with a wavelength that contributes to photoelectric conversion in each photoelectric conversion layer is increased, the photoelectric conversion efficiency is improved, and the laminated thin film with excellent photoelectric conversion efficiency that enables effective use of sunlight. A solar cell can be produced.

  In the above-described embodiment, the case where the photoelectric conversion layer is two layers has been described. However, even when the present invention is applied to a stacked thin film solar cell in which three or more photoelectric conversion layers are stacked, The effect of the present invention can be obtained in the same manner as above.

Embodiment 2. FIG.
In the first embodiment described above, the unevenness formation interval of the light scattering texture 4a on the surface of the intermediate layer 4 is different from the unevenness formation interval of the texture 2a, whereby the texture on the light incident side of the second photoelectric conversion layer 5 is changed. The unevenness formation interval P2 is configured to be longer than the unevenness formation interval P1 of the texture on the light incident side of the first photoelectric conversion layer 3, but for light scattering at the interface between the first photoelectric conversion layer 3 and the intermediate layer 4. The unevenness formation interval of the texture may be different from the unevenness formation interval of the texture 2a.

  FIG. 4 is a cross-sectional view schematically showing a configuration of a stacked thin-film solar cell that is a thin-film solar cell according to the second embodiment of the present invention. As shown in FIG. 4, the laminated thin film solar cell according to the present embodiment includes a translucent substrate 1, a front transparent electrode layer 2 formed on the translucent substrate 1 and serving as a first electrode layer, and a front transparent electrode. A first photoelectric conversion layer 3 which is a first thin film semiconductor layer formed on the layer 2, an intermediate layer 4 formed on the first photoelectric conversion layer 3, and a second thin film semiconductor formed on the intermediate layer 4. The second photoelectric conversion layer 5, which is a layer, the back transparent conductive film 6 formed on the second photoelectric conversion layer 5, and the back electrode layer 7 serving as the second electrode layer formed on the back transparent conductive film 6 are sequentially formed. It has a laminated structure. In this laminated thin film solar cell, the light transmitting substrate 1 side is the light incident side on which sunlight 50 is incident.

  In FIG. 4, the same members as those in the first embodiment are denoted by the same reference numerals as those in FIG. Below, a different part from Embodiment 1 is demonstrated.

  The first photoelectric conversion layer 3 has irregularities formed on the surface on the intermediate layer 4 side (interface between the first photoelectric conversion layer 3 and the intermediate layer 4) as a light scattering texture 3a (hereinafter referred to as texture 3a). ing. The unevenness of the light scattering texture 3 a is formed at a predetermined unevenness formation interval P <b> 3 in the in-plane direction of the first photoelectric conversion layer 3. And the uneven | corrugated formation space | interval P3 is made longer than the uneven | corrugated formation space | interval P1 of the texture 2a.

  Here, the height of the unevenness of the light scattering texture 3a is the average height difference of the unevenness. Moreover, the uneven | corrugated formation space | interval P3 of the texture 3a for light scattering is the distance (or adjacent) between the vertex positions of the adjacent convex part in the in-plane direction of the 1st photoelectric converting layer 3 in the uneven texture 3a for light scattering. Distance between the bottom positions of the recesses). This texture causes light scattering and refraction, and provides a light confinement effect in the photoelectric conversion layer below the front conductive film, thereby improving the short-circuit current density. The aspect ratio (height / unevenness formation interval P3) between the unevenness height of the light scattering texture 3a and the unevenness formation interval P3 is preferably in the range of 1 to 1/4.

  FIG. 5 is a schematic diagram showing the relationship between the transmission and scattering of sunlight in the stacked thin film solar cell according to the second embodiment configured as described above. In the first photoelectric conversion layer 3 made of amorphous silicon (a-Si), sunlight 51 having a wavelength of about 350 nm to 600 nm is used for photoelectric conversion, and particularly, the photoelectric conversion efficiency of the sunlight 51 having a wavelength near about 500 nm is high. . Therefore, in the stacked thin film solar cell according to the second embodiment, the first photoelectric conversion layer in the front transparent electrode layer 2 is used to refract the sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3 with the texture 2a. The unevenness formation interval P1 of the light scattering texture 2a formed at the interface on the 3 side is in the range of the same level to 1/2 of the wavelength of sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3, that is, 250 nm to It is set to 500 nm.

  By providing the texture 2a having such a periodic structure, the sunlight 51 (sunlight having a wavelength of approximately 350 nm to 600 nm) used for photoelectric conversion in the first photoelectric conversion layer 3 is the interface of the texture 2a, that is, the first The light is refracted at the light incident side interface in the photoelectric conversion layer 3 and enters the first photoelectric conversion layer 3. Thereby, the optical path length of the sunlight 51 in the 1st photoelectric converting layer 3 becomes long, and a photoelectric conversion efficiency can be improved. In order to prevent reflection of the sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3 in the texture 2a, the unevenness formation interval P1 of the texture 2a is preferably about 250 nm to 350 nm.

  Moreover, since the sunlight 52 (sunlight having a wavelength of about 500 nm to 900 nm) used for photoelectric conversion in the second photoelectric conversion layer 5 has a longer wavelength than the light used in the first photoelectric conversion layer 3, the interface of the texture 2a. The light is incident on the first photoelectric conversion layer 3 without bending. Thereby, the optical path length of the sunlight 52 in the 1st photoelectric converting layer 3 can be shortened, the absorption loss of the sunlight 52 in a 1st photoelectric converting layer can be reduced, and a photoelectric conversion efficiency can be improved.

  On the other hand, in the second photoelectric conversion layer 5 made of amorphous silicon germanium (a-SiGe), sunlight having a wavelength of about 500 nm to 900 nm is used for photoelectric conversion, and in particular, the photoelectric conversion efficiency of sunlight 51 having a wavelength of about 700 nm. Is expensive. Therefore, in the stacked thin-film solar cell according to the second embodiment, in order to refract sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 with the texture 3a, the intermediate layer 4 in the first photoelectric conversion layer 3 The unevenness formation interval P3 of the light scattering texture 3a formed at the interface is set to the same level to 1/2 wavelength as the wavelength of sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5, that is, 350 nm to 700 nm. is doing.

  By providing the texture 3a having such a periodic structure, sunlight 52 (sunlight having a wavelength of approximately 500 nm to 900 nm) used for photoelectric conversion in the second photoelectric conversion layer 5 is the interface of the texture 3a, that is, the second The light is incident on the light incident side of the photoelectric conversion layer 5 at the interface between the first photoelectric conversion layer 3 and the intermediate layer 4 and is incident on the second photoelectric conversion layer 5. Thereby, the optical path length of the sunlight 52 in the 2nd photoelectric converting layer 5 becomes long, and a photoelectric conversion efficiency can be improved. In order to prevent reflection of the sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 in the texture 3a, the unevenness formation interval P3 of the texture 3a is preferably about 350 nm to 600 nm.

  As described above, in the stacked thin film solar cell according to the second embodiment, the surface (front transparent) on the light incident side of the first photoelectric conversion layer 3 and on the first photoelectric conversion layer 3 side in the front transparent electrode layer 2. Light scattering texture 2a formed on the electrode layer 2 and the first photoelectric conversion layer 3) and the light incident side of the second photoelectric conversion layer 5 and the intermediate layer 4 side of the first photoelectric conversion layer 3 A light scattering texture 3a formed on the surface (interface between the first photoelectric conversion layer 3 and the intermediate layer 4). And the uneven | corrugated formation space | interval P1 of the texture 2a is shorter than the wavelength of the sunlight 52 used for photoelectric conversion in the 2nd photoelectric converting layer 5, and the uneven | corrugated space | interval P3 of the texture 3a is longer than the uneven | corrugated space | interval P1 of the texture 2a. Is set.

  By having such a configuration, light (sunlight 51) having a wavelength used for photoelectric conversion in the first photoelectric conversion layer 3 among the incident sunlight is texture on the light incident side of the first photoelectric conversion layer 3. Since the light is refracted by 2a and is incident on the first photoelectric conversion layer 3 from an oblique direction, the optical path length is increased and the power generation efficiency is increased. Moreover, since the wavelength of light (sunlight 52) used for the photoelectric conversion in the second photoelectric conversion layer 5 is longer than the light used for the photoelectric conversion in the first photoelectric conversion layer 3, the first photoelectric conversion layer 3 The light incident side texture 2a is transmitted without being refracted, and the optical path when passing through the first photoelectric conversion layer 3 is the shortest, so that absorption loss in the first photoelectric conversion layer 3 can be prevented. Furthermore, the unevenness formation interval P3 of the texture 3a on the light incident side of the second photoelectric conversion layer 5 is made longer than the unevenness formation interval P1 of the texture 2a on the light incident side of the first photoelectric conversion layer 3, thereby making the second photoelectric conversion layer 5 Since the light used for photoelectric conversion is refracted and incident obliquely on the second photoelectric conversion layer, the optical path length in the second photoelectric conversion layer 5 is increased, and the photoelectric conversion efficiency is improved.

  Therefore, according to the multilayer thin film solar cell according to the second embodiment, the unevenness formation interval in the texture on the light incident side of each photoelectric conversion layer is changed according to the wavelength of light used by each photoelectric conversion layer for photoelectric conversion. As a result, the optical path length of sunlight having a wavelength that contributes to photoelectric conversion in each photoelectric conversion layer is increased, and the photoelectric conversion efficiency is improved. As in the stacked thin film solar cell according to the first embodiment, effective use of sunlight is achieved. A multilayer thin film solar cell having excellent photoelectric conversion efficiency has been realized.

  Next, a method for manufacturing the stacked thin film solar cell according to the present embodiment configured as described above will be described with reference to FIGS. 6A to 6E are cross-sectional views for explaining the method for manufacturing the stacked thin-film solar cell according to the second embodiment.

  First, the translucent substrate 1 is prepared. Here, for example, a flat white glass plate is used as the translucent substrate 1. A front transparent electrode layer 2 is formed on the translucent substrate 1 by a known method. For example, the front transparent electrode layer 2 made of a zinc oxide (ZnO) film is formed on the translucent substrate 1 by a sputtering method. Further, as a film formation method, another film formation method such as a CVD method may be used. Then, unevenness is formed on the surface of the front transparent electrode layer 2 as a light scattering texture 2a, for example, by wet etching at a predetermined unevenness formation interval P1 (FIG. 6-1).

  Next, the 1st photoelectric converting layer 3 which has the texture 3a for light scattering on the surface is formed on the front transparent electrode layer 2 (FIG. 6-2). For example, a p-type semiconductor layer and an i-type semiconductor layer (not shown) made of amorphous silicon (a-Si) are sequentially stacked on the front transparent electrode layer 2 by plasma CVD as the first photoelectric conversion layer 3. Next, a resist is applied in a pattern with an arbitrary interval (P3), and the surface of the i-type semiconductor layer is wet-etched using the resist as a mask, thereby forming irregularities as light scattering texture 3a on the surface of the i-type semiconductor layer. It is formed at a predetermined unevenness formation interval P3. Subsequently, ion implantation is performed on the i-type semiconductor layer to modify the surface of the i-type semiconductor layer into an n-type semiconductor layer. Thereby, the 1st photoelectric converting layer 3 which has the texture 3a for light scattering formed in the predetermined uneven | corrugated formation space | interval P3 different from the texture 2a on the surface can be formed.

Next, the intermediate layer 4 is formed on the entire surface of the first photoelectric conversion layer 3 by a known method. For example, a doped silicon oxide (SiO _x ) film is formed on the first photoelectric conversion layer 3 by the plasma CVD method as the intermediate layer 4 (FIG. 6-3).

  Next, the second photoelectric conversion layer 5 is formed on the intermediate layer 4 by a known method (FIG. 6-4). For example, a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer (not shown) made of amorphous silicon germanium (a-SiGe) are sequentially stacked on the intermediate layer 4 by the plasma CVD method as the second photoelectric conversion layer 5.

  Next, the back surface transparent conductive film 6 is formed on the second photoelectric conversion layer 5 by a known method. For example, the back transparent conductive film 6 made of a zinc oxide (ZnO) film is formed on the second photoelectric conversion layer 5 by a sputtering method. Further, as a film formation method, another film formation method such as a CVD method may be used.

  Subsequently, the back electrode layer 7 is formed on the back transparent conductive film 6 by a known method. For example, the back electrode layer 7 made of a silver (Ag) film having a high reflectance is formed on the back transparent conductive film 6 by a sputtering method (FIGS. 6-5). Through the above processing, the stacked thin film solar cell according to the present embodiment shown in FIG. 4 is obtained.

  As described above, in the method for manufacturing the stacked thin-film solar cell according to the second embodiment, the surface on the light incident side of the first photoelectric conversion layer 3 and the first photoelectric conversion layer 3 side in the front transparent electrode layer 2. Light scattering is performed so that the unevenness formation interval P1 is shorter than the wavelength of sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 (at the interface between the front transparent electrode layer 2 and the first photoelectric conversion layer 3). The texture 2a is formed. And the uneven | corrugated formation space | interval P3 is on the light-incidence side of the 2nd photoelectric converting layer 5, and the surface (interface of the 1st photoelectric converting layer 3 and the intermediate | middle layer 4) of the 1st photoelectric converting layer 3 side. The light scattering texture 3a is formed so as to be longer than the unevenness formation interval P1 of the texture 2a.

  By forming such a light scattering texture 2a and texture 3a, only the sunlight 51 used for photoelectric conversion in the first photoelectric conversion layer 3 is refracted and incident on the first photoelectric conversion layer 3. Sunlight 52 used for photoelectric conversion in the second photoelectric conversion layer 5 is refracted and incident on the second photoelectric conversion layer 5. Thereby, in each photoelectric conversion layer, the optical path length of the sunlight of the wavelength which contributes to photoelectric conversion in each photoelectric conversion layer becomes long, and photoelectric conversion efficiency improves. On the other hand, in the first photoelectric conversion layer 3, sunlight 52 having a wavelength that does not contribute to photoelectric conversion in the first photoelectric conversion layer 3 is transmitted without being refracted, so that the optical path length in the first photoelectric conversion layer 3 is shortened. Thereby, the absorption loss in the 1st photoelectric converting layer 3 can be reduced, and since more sunlight 52 injects into the 2nd photoelectric converting layer 5, a photoelectric efficiency improves.

  Therefore, according to the method for manufacturing a stacked thin-film solar cell according to the second embodiment, the unevenness formation interval in the texture on the light incident side of each photoelectric conversion layer is set according to the wavelength of light that each photoelectric conversion layer uses for photoelectric conversion. By changing the photoelectric conversion layer, the optical path length of sunlight having a wavelength that contributes to photoelectric conversion is increased, and the photoelectric conversion efficiency is improved. A laminated thin film solar cell excellent in conversion efficiency can be produced.

  In addition, although embodiment mentioned above has demonstrated the case where the 1st photoelectric converting layer 3 and the 2nd photoelectric converting layer 5 are provided as a photoelectric converting layer, it has a structure where the photoelectric converting layer of three or more layers was laminated | stacked. In the case of a stacked thin-film solar cell, the first photoelectric conversion layer 3 is generalized by replacing it with “Xth photoelectric conversion layer” and the second photoelectric conversion layer 5 with “(X + 1) photoelectric conversion layer”. can do. Here, X represents the order from the light receiving surface among the plurality of stacked photoelectric conversion layers. In such a stacked thin film solar cell, the above-described effects of the present invention are obtained by adopting the same structure as described above with respect to the “Xth photoelectric conversion layer” and the “(X + 1) photoelectric conversion layer”. It is possible.

  Moreover, although embodiment mentioned above demonstrated the case where the sunlight 51 used for photoelectric conversion in the 1st photoelectric converting layer 3 was refracted by the texture 2a for light scattering, on the light incident side of the 1st photoelectric converting layer 3 It is also possible to adopt a configuration in which the sunlight 51 is refracted by the light scattering texture formed on the surface of the translucent substrate 1 (interface between the translucent substrate 1 and the front transparent electrode layer 2). Even in this case, the above-described effects of the present invention can be obtained.

  As described above, the thin film solar cell according to the present invention is useful for realizing a thin film solar cell excellent in photoelectric conversion efficiency using light effectively.

DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 2 Front transparent electrode layer 2a Texture structure 3 Photoelectric conversion layer 3a Texture structure 4 Intermediate layer 4a Texture structure 5 Photoelectric conversion layer 6 Back surface transparent conductive film 7 Back surface electrode layer 50 Sunlight 51 Sunlight 52 Sunlight P1 Irregularity Formation interval P2 Concavity and convexity formation interval P3 Concavity and convexity formation interval

Claims (6)

On the translucent substrate, a first electrode layer made of a transparent conductive film, a first photoelectric conversion layer that performs photoelectric conversion, an intermediate layer, a second photoelectric conversion layer that performs photoelectric conversion, a second electrode layer, In this order,
A first texture structure comprising a plurality of irregularities is formed on the light incident side of the first photoelectric conversion layer,
A second texture structure having a plurality of irregularities is formed between the first photoelectric conversion layer and the second photoelectric conversion layer on the light incident side of the second photoelectric conversion layer;
The formation interval of the unevenness in the first texture structure is shorter than the wavelength of light used for photoelectric conversion in the second photoelectric conversion layer,
The irregularity formation interval in the second texture structure is longer than the irregularity formation interval in the first texture structure;
A thin film solar cell characterized by The second texture structure is formed on the second photoelectric conversion layer side in the intermediate layer;
The thin film solar cell according to claim 1. The second texture structure is formed on the intermediate layer side of the first photoelectric conversion layer;
The thin film solar cell according to claim 1. On the translucent substrate, a first electrode layer made of a transparent conductive film, a first photoelectric conversion layer that performs photoelectric conversion, an intermediate layer, a second photoelectric conversion layer that performs photoelectric conversion, a second electrode layer, A thin film solar cell manufacturing method having
Forming a first texture structure comprising a plurality of irregularities on the light incident side of the first photoelectric conversion layer;
Forming a second texture structure comprising a plurality of irregularities between the first photoelectric conversion layer and the second photoelectric conversion layer on the light incident side of the second photoelectric conversion layer;
Including
The formation interval of the unevenness in the first texture structure is shorter than the wavelength of light used for photoelectric conversion in the second photoelectric conversion layer,
The irregularity formation interval in the second texture structure is longer than the irregularity formation interval in the first texture structure;
A method for producing a thin film solar cell. Forming the first electrode layer having the first texture structure on the surface thereof on the translucent substrate;
Forming the first photoelectric conversion layer on the first electrode layer;
Forming the intermediate layer having the second texture structure on the surface thereof on the first photoelectric conversion layer;
Forming the second photoelectric conversion layer on the intermediate layer;
Forming the second electrode layer on the second photoelectric conversion layer;
Including,
The manufacturing method of the thin film solar cell of Claim 4 characterized by these. Forming the first electrode layer having the first texture structure on the surface thereof on the translucent substrate;
Forming the first photoelectric conversion layer having the second texture structure on the surface on the first electrode layer;
Forming the intermediate layer on the first photoelectric conversion layer;
Forming the second photoelectric conversion layer on the intermediate layer;
Forming the second electrode layer on the second photoelectric conversion layer;
Including,
The manufacturing method of the thin film solar cell of Claim 4 characterized by these.

Images