JP2005183945A - Photoelectric converter and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric converter having higher photoelectric conversion characteristics by drawing the light energy incident on a gap between granular photoelectric conversion bodies into the granular photoelectric conversion body adjacent to the gap while maintaining reliability. <P>SOLUTION: In the photoelectric converter, a number of granular photoelectric conversion bodies for performing photoelectric conversion are arranged on one main surface of a substrate 1 as one electrode, an insulator layer 3 is provided at the lower part between a number of the granular photoelectric conversion bodies, and the other electrode 5 and a translucent cover body 7 are formed along the external surface of the granular photoelectric converter bodies and the insulator layer 3 on the upper part of a number of the granular photoelectric converter bodies and the insulator layer 3. Consequently, the photoelectric converter having high reliability and conversion efficiency can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion device and a method for manufacturing the same, and more particularly to a photoelectric conversion device using a granular crystal semiconductor used for solar power generation and the like.

A conventional photoelectric conversion device using a granular crystal semiconductor is shown in FIG. In this photoelectric conversion device, an opening is formed in the first aluminum foil 23, a silicon sphere having an n-type outer shell 22 is inserted on the p-type central core 21, and an n-type outer shell on the back side of the silicon sphere is inserted. 22 is removed, and an insulator layer 24 is formed on the surface of the silicon sphere from which the first aluminum foil 23 and the n-type outer shell 22 have been removed, and after removing the insulator layer on the upper back side of the silicon sphere, Two aluminum foils 26 are joined, and a spherical lens 27 is disposed on the n-type outer shell 22 and the first aluminum foil 23. Thus, when a granular crystal semiconductor such as a silicon sphere is used, a gap is generated between the granular crystal semiconductors, resulting in a photoelectric conversion loss. Thus, a photoelectric conversion device is disclosed in which a spherical lens 27 is formed on the granular crystal semiconductor in order to draw light energy incident on the gap between the granular crystal semiconductors into the granular crystal semiconductor adjacent to the gap (for example, Patent Documents). 1).
US Patent 5419782

  However, in the photoelectric conversion device as shown in FIG. 6, since the silicon sphere is inserted by making a hole in the first aluminum foil 23, the silicon sphere is used to maintain the foil shape of the first aluminum foil 23. Therefore, the projected area ratio of all silicon spheres to the area of the photoelectric conversion device is about 75%. In order to draw the light energy incident on the gap between the silicon spheres (about 25%) due to the wide spacing to the silicon sphere adjacent to the gap, it is necessary to change the shape of contact between the spherical lenses abruptly. there were. However, a shape that does not conform to the shape of the first aluminum foil 23 that is an electrode and that suddenly changes the shape of contact between the spherical lenses is insufficiently reliable as protection for the first aluminum foil 23. In some cases, the surface of the first aluminum foil 23 is corroded, and reflection of light energy from the first aluminum foil 23 cannot be obtained, resulting in a decrease in photoelectric conversion efficiency.

  The present invention has been made in view of the above-mentioned problems in the prior art, and its purpose is to draw light energy incident on the gap between the granular crystal semiconductors into the granular crystal semiconductor adjacent to the gap while maintaining reliability. Therefore, it is providing the photoelectric conversion apparatus with a higher photoelectric conversion characteristic.

  In order to achieve the above object, the photoelectric conversion device of the present invention is provided with 1) a large number of granular photoelectric conversion bodies that perform photoelectric conversion on one main surface of a substrate that serves as one electrode. An insulating layer is provided between the granular photoelectric converters, and above the granular photoelectric converters and on the insulating layer, along the surfaces of the granular photoelectric converters and the insulating layer. The other electrode is provided, and a translucent cover body is provided on the other electrode along the surface thereof. In particular, the projected area ratio of the granular photoelectric conversion body disposed on the substrate to the area of the substrate is preferably 80% or more.

  2) In the above 1), the translucent cover body is a resin film.

  3) In the above 1) or 2), the translucent protective plate is disposed so as to be in contact with a portion of the translucent cover body located at the top of the granular photoelectric conversion body.

  4) In the above 3), a translucent filler having a refractive index lower than that of the translucent cover body is filled between the translucent cover body and the translucent protective plate. And

  5) In the above 1), the translucent cover body is made of a thermoplastic material, and the translucent resin film, the translucent buffer layer made of the thermoplastic material and the translucent material are formed on the translucent cover body. The protective plates are sequentially stacked.

  6) In the above 5), the surface of the translucent resin film in contact with the translucent cover body is covered with the same thermoplastic material as that of the translucent cover body. .

  The manufacturing method of the photoelectric conversion device of the present invention is as follows: 7) A large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed on one main surface of a substrate that is one electrode, and these multiple granular photoelectric conversions An insulator layer is provided at the lower part between the bodies, and the other electrode is provided on the upper part of the plurality of granular photoelectric converters and on the insulator layer along the surfaces of the granular photoelectric converters and the insulator layer. Disposing a translucent resin film on the other electrode, and deforming the resin film along the surface of the other electrode by heating the resin film at a temperature equal to or higher than a softening point. It is characterized by including.

  8) A large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed on one main surface of the substrate that is to be one of the electrodes, and an insulator layer is provided below the multiple granular photoelectric conversion bodies. A step of providing the other electrode along the surfaces of the granular photoelectric converter and the insulator layer on top of the multiple granular photoelectric converters and the insulator layer, and on the other electrode. A step of providing a translucent resin film along the surface thereof, and a translucent filler having a refractive index lower than that of the resin film on the resin film, and the granular photoelectric conversion body of the resin film And a step of disposing a translucent protective plate so as to be in contact with a portion located at the top of the substrate.

  According to the photoelectric conversion device of 1) and the manufacturing method of 7), along the surfaces of the granular photoelectric converters and the insulator layer, on the top of the multiple granular photoelectric converters and on the insulator layer. The other electrode is provided, and a translucent cover body is provided on the other electrode along the surface thereof. Also, on one main surface of the substrate to be one of the electrodes, a large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed, and an insulating layer is provided below these multiple granular photoelectric conversion bodies, A step of providing the other electrode along the surfaces of the granular photoelectric converter and the insulator layer on top of the plurality of granular photoelectric converters and the insulator layer; Disposing a light-sensitive resin film and deforming the resin film along the surface of the other electrode by heating the resin film at a temperature equal to or higher than the softening point. Thus, by covering the translucent cover body on the other electrode relatively uniformly, the other electrode is not exposed, and direct attacks such as humidity can be prevented, while maintaining reliability. The light energy incident on the gap between the granular photoelectric converters can be efficiently drawn into the granular crystal semiconductor adjacent to the gap, thereby providing a photoelectric conversion device with high photoelectric conversion characteristics and high reliability. Become.

  Moreover, according to the photoelectric conversion apparatus of said 2), since the said translucent cover body is a resin film, preparation of the outstanding photoelectric conversion apparatus like said 1) can be performed simply and easily.

  Further, according to the photoelectric conversion device of 3) and the manufacturing method of 8), the translucent protective plate is disposed in contact with the portion of the translucent cover body located at the top of the granular photoelectric conversion body. Has been. Also, on one main surface of the substrate to be one of the electrodes, a large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed, and an insulating layer is provided below these multiple granular photoelectric conversion bodies, A step of providing the other electrode along the surfaces of the granular photoelectric conversion body and the insulator layer on top of the plurality of granular photoelectric conversion bodies and on the insulator layer; A step of providing a translucent resin film along the surface, and a translucent filler having a lower refractive index than the resin film is disposed on the resin film, and the top of the granular photoelectric conversion body of the resin film And a step of disposing a translucent protective plate so as to be in contact with a portion located at the position. As a result, when a translucent protective plate is simply provided on the translucent cover body, the incident light energy is transmitted by the air layer being sandwiched between the translucent cover body and the translucent protective plate. Energy loss occurs due to reflection at the interface between the entire surface of the light protection plate and the air layer, but the back surface of the light transmission protection plate and a part of the light transmission cover body located at the top of the granular photoelectric conversion body are closely attached. Thus, it is possible to reduce the energy loss due to the provision of the translucent protective plate by reducing the interface where the light energy is reflected.

  Further, according to the photoelectric conversion device of 4), a translucent filler having a lower refractive index than that of the translucent cover body is provided between the translucent cover body and the translucent protective plate. Therefore, when the incident light energy passes through the filler and enters the translucent cover body, the light energy can be refracted to the granular photoelectric converter side and taken into the granular photoelectric converter, and the conversion efficiency is excellent. A photoelectric conversion device can be provided.

  Moreover, according to the photoelectric conversion device of said 5), 6), reliability is maintained, absorbing the dispersion | variation in the particle size of a granular photoelectric conversion body, and the fine waviness of a translucent protective board, and between granular photoelectric conversion bodies. By drawing the light incident on the gap into the adjacent granular photoelectric converter through the gap, it is possible to provide a photoelectric conversion device with higher photoelectric conversion characteristics.

  Embodiments of the present invention will be described below in detail with reference to the drawings schematically showing the embodiments.

  FIG. 1 is a cross-sectional view showing an embodiment of the photoelectric conversion device of the present invention. In FIG. 1, 1 is a substrate, 2 is a granular crystal semiconductor constituting a granular photoelectric converter, 3 is an insulator layer made of an insulating material, 4 is a semiconductor layer constituting a granular photoelectric converter, 5 is a transparent conductive layer, 6 Is an alloy layer of, for example, aluminum of the substrate and silicon of the granular crystal semiconductor, and 7 is a translucent cover. In addition, the board | substrate 1 is good also as what provided the electrode layer which consists of aluminum on the insulator.

  The substrate 1 may be any metal or ceramic having a melting point equal to or higher than that of aluminum. For example, aluminum, aluminum alloy, iron, stainless steel, nickel alloy, alumina, or the like is used. When the material of the board | substrate 1 is other than aluminum, it is set as the structure of the material and the electrode layer (not shown) which consists of aluminum.

  First, a large number of first-conductivity-type granular crystal semiconductors 2 are arranged on a substrate 1. The granular crystal semiconductor 2 contains a trace amount of elements such as B, Al, Ga or the like for exhibiting p-type in Si, or P or As for exhibiting n-type. The shape of the granular crystal semiconductor 2 may be a polyhedron, a rounded corner, a curved surface, etc., and the particle size distribution may be uniform or non-uniform. Therefore, a non-uniformity is more advantageous in order to reduce the cost. Furthermore, by having a convex curved surface, the dependency of the incident light on the ray angle can be reduced.

  The particle size of the granular crystal semiconductor 2 is preferably 0.2 to 0.8 mm. This is because if the thickness exceeds 0.8 mm, the amount of silicon used in the conventional crystal plate type photoelectric conversion device including the cutting portion will not be changed, and the merit of using the granular crystal semiconductor will be lost. This is because another problem that it is difficult to assemble to 1 occurs. Therefore, the particle size of the granular crystal semiconductor 2 is more preferably 0.2 to 0.6 mm in relation to the amount of silicon used.

  After arranging a large number of granular crystal semiconductors 2 on the substrate 1, the substrate 1 and the granular material are heated by heating to a eutectic temperature of 577 ° C. or higher between the aluminum of the substrate 1 and the silicon of the granular crystal semiconductor 2 with a certain weight. The substrate 1 and the granular crystal semiconductor 2 are bonded via the alloy layer 6 of the crystal semiconductor 2.

The insulator layer 3 is made of an insulating material for separating the positive electrode and the negative electrode. For example, SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , CaO, MgO, P ₂ O ₅ , Li ₂ O, SnO, ZnO , BaO, TiO ₂ or the like as a main component, a low-temperature firing glass material alone, a glass composition in which a filler composed of one or more of the above materials is combined, or an organic insulating substance such as a silicone resin Etc. are used.

  The insulating material is applied on the granular crystal semiconductor 2 and filled by heating at a temperature not higher than 577 ° C., which is the eutectic temperature of aluminum and silicon, to form the insulating layer 3. When the heating temperature exceeds 577 ° C., the alloy layer 15 of aluminum and silicon starts to melt, so that the bonding between the substrate 1 and the granular crystal semiconductor 2 becomes unstable. The power generation current can no longer be taken out. After forming the insulator layer 3, in order to clean the surface of the granular crystal semiconductor 2, it is cleaned with a cleaning liquid containing hydrofluoric acid.

  The semiconductor layer 4 is made of, for example, Si, and a small amount of a vapor phase of a phosphorus compound for exhibiting n-type in a gas phase of a silane compound or a gas phase of a boron compound exhibiting p-type is introduced by a vapor phase growth method or the like. Form. The film quality may be either crystalline, amorphous, or a mixture of crystalline and amorphous, but in consideration of light transmittance, a crystalline or a mixture of crystalline and amorphous is preferable. A part of incident light is transmitted through the semiconductor layer 4 in a portion where the granular crystal semiconductor 2 is not present, reflected by the lower substrate 1 and irradiated onto the granular crystal semiconductor 2, thereby irradiating the entire photoelectric conversion device with light energy. Can be efficiently irradiated onto the granular crystal semiconductor 2.

The concentration of the trace element in the semiconductor layer 4 is, for example, about 1 × 10 ¹⁶ to 10 ²¹ atoms / cm ³ . Furthermore, it is desirable that the semiconductor layer 4 is formed along the convex curved surface shape of the surface of the granular crystal semiconductor 2. By forming along the convex curved surface of the granular crystal semiconductor 2, the area of the pn junction can be increased widely, and carriers generated inside the granular crystal semiconductor 2 can be efficiently collected. In the case of using a granular crystal semiconductor 2 whose outer shell contains a trace amount of elements such as P, As, etc. exhibiting reverse conductivity, that is, n-type, or B, Al, Ga, etc., exhibiting p-type, the semiconductor layer 4 may be omitted, and the following transparent conductive layer 5 may be formed thereon.

When the semiconductor layer 4 or the granular crystal semiconductor 2 contains a small amount of an element of reverse conductivity type on the outer surface, the transparent conductive layer 5 that also serves as the other electrode is formed on the granular crystal semiconductor 2. The transparent conductive layer 5 is made of one or a plurality of oxide films selected from SnO ₂ , In ₂ O ₃ , ITO, ZnO, TiO _2, etc., and includes a sputtering method, a vapor phase growth method, a coating baking method, and the like. Form with. The transparent conductive layer 5 can be expected to have an effect as an antireflection film if the film thickness is selected. The transparent conductive layer 5 needs to be transparent, and a part of incident light is transmitted through the transparent conductive layer 5 in a portion where the granular crystal semiconductor 2 is not present, and is reflected by the lower substrate 1 to be granular crystal semiconductor 2. It is possible to efficiently irradiate the granular crystal semiconductor 2 with the light energy applied to the entire photoelectric conversion device. The transparent conductive layer 5 is preferably formed along the surface of the semiconductor layer 4 or the granular crystal semiconductor 2 and is formed along the convex curved surface shape of the granular crystal semiconductor 2. When formed along the convex curved surface of the granular crystal semiconductor 2, the area of the pn junction can be increased, and carriers generated inside the granular crystal semiconductor 2 can be collected efficiently.

A protective layer (not shown) may be formed on the semiconductor layer 4 or the transparent conductive layer 5. Such a protective layer preferably has a characteristic of a transparent dielectric, such as silicon oxide, cesium oxide, aluminum oxide, silicon nitride, titanium oxide, SiO ₂ —TiO ₂ , tantalum oxide, by CVD or PVD. Yttrium oxide or the like is formed on the semiconductor layer 4 or the transparent conductive layer 5 as a single layer or a combination of single or multiple compositions. The protective layer needs to be transparent because it is in contact with the light incident surface, and may be a dielectric material in order to prevent leakage between the semiconductor layer 4 or the transparent conductive layer 5 and the outside. is necessary. In addition, if the thickness of the protective layer is optimized, a function as an antireflection film can be expected.

  In order to reduce the series resistance value, a pattern electrode composed of finger electrode portions (not shown) and bus bar electrode portions (not shown) having a constant interval is provided as an upper electrode on the semiconductor layer 4 or the transparent conductive layer 5 directly or You may connect with the semiconductor layer 4 indirectly.

  A translucent cover body 7 is provided on the transparent conductive layer 5 which also serves as the other electrode so as to follow the shape of the transparent conductive layer 5. The light energy incident on the gap between the granular crystal semiconductors 2 is refracted in the direction of the granular crystal semiconductor 2 by the translucent cover 7 and drawn into the granular crystal semiconductor 2 adjacent to the gap. Moreover, since the translucent cover body 7 is provided along the shape of the transparent conductive layer 5, the transparent conductive layer 5 is not exposed and a direct attack such as humidity is prevented. In order to form a continuous lens shape with the translucent cover body 7, the projected area ratio of the whole granular crystal semiconductor 2 to the area of the photoelectric conversion device needs to be 80% or more. This is because if it is less than 80%, the gap between the granular crystal semiconductors 2 is widened, and therefore, a portion of the translucent cover body 7 opposite to the substrate is formed in parallel with the substrate. This is because the light energy incident on the gap between them cannot be drawn into the granular crystal semiconductor 2 adjacent to the gap, and the improvement in photoelectric conversion characteristics is reduced.

  As a material of the translucent cover body 7, any material may be used as long as it is optically transparent and the translucent cover body 7 itself can conform to the shape of the transparent conductive layer 5 with thermoplasticity that is softened by heat. Resin films are preferred. For example, acrylic, polyethylene, EVA (ethylene vinyl acetate), silicone resin, and other transparent thermoplastic resins can be formed on the transparent conductive layer 5 in the form of a film, and dried from above with a dryer or the like. A method of spraying hot air on the softening temperature so as to follow the shape of the transparent conductive layer 5 (herein referred to as hot air method), dissolving in an organic solvent or the like, applying the solution onto the transparent conductive layer 5 and then drying. A method of forming the transparent conductive layer 5 so as to conform to the shape of the transparent conductive layer 5 (herein referred to as a coating method), and forming a concave / convex negative mold of the granular crystal semiconductor 2 on the substrate 1 with a heat-resistant material. There is a method in which a film-like material is sandwiched between 5 and pressurizing while heating (herein referred to as a mold forming method). However, there is a simpler coating method or a hot air method with less environmental problems. Masui. Although the film thickness of the translucent cover body 7 depends on the particle diameter of the granular crystal semiconductor 2, it is, for example, about 20 to 100 μm, and if it is less than 20 μm, it is too thin to obtain the effect and it is difficult to form a layer. When the thickness exceeds 100 μm, the translucent cover body 7 falls and the shape along the shape of the transparent conductive layer 5 cannot be obtained, and it becomes difficult to enter the gaps between the narrow granular crystal semiconductors 2, and the effect is difficult to obtain.

  As described above, the photoelectric conversion device of the present invention includes the other electrode and the light transmission along the outer surface of the granular photoelectric conversion body and the insulator layer on the upper part and the insulating layer of the large number of granular photoelectric conversion bodies. Since the transparent cover body is sequentially formed, the light energy incident on the gap between the granular photoelectric converters is maintained while maintaining reliability by covering the translucent cover body on the other electrode relatively uniformly. It can be efficiently drawn into the granular crystal semiconductor adjacent to the gap, thereby providing a photoelectric conversion device with high photoelectric conversion characteristics and high reliability. Further, in this case, a large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed on one main surface of the substrate that is to be one of the electrodes, and an insulator is provided below these multiple granular photoelectric conversion bodies. Forming the other electrode along the outer shape of the granular photoelectric conversion body and the insulating layer on the upper part of the granular photoelectric conversion body and the insulating layer, and on the other electrode The step shown in FIG. 1 is performed by sequentially performing a process of arranging a translucent resin film and deforming the resin film along the outer surface of the granular photoelectric converter by heating at a temperature equal to or higher than the softening point. A conversion device can be easily produced.

  In order to further improve the reliability of the photoelectric conversion device, the structure shown in FIG. 2 or FIG. 3 is preferable. FIG. 2 is a cross-sectional view showing a photoelectric conversion device in which a translucent protective plate 8 is provided on the translucent cover body 7 of the photoelectric conversion device shown in FIG. When the translucent protective plate 8 is simply provided on the translucent cover body 7, the incident light energy is caused by the air layer 9 being sandwiched between the translucent cover body 7 and the translucent protective plate 8. Is reflected at the interface between the entire surface of the translucent protective plate 8 and the air layer 9, and energy loss occurs. Therefore, in order to reduce energy loss, the back surface of the translucent protective plate 8 and a part of the translucent cover body 7 at the top of the granular crystal semiconductor 2 are brought into close contact with each other, thereby reducing the interface where the light energy is reflected. It becomes possible to reduce energy loss due to the provision of the translucent protective plate 8.

  The photoelectric conversion device shown in FIG. 2 is manufactured by placing a light-transmitting protective plate 8 on the light-transmitting cover body 7 of the photoelectric conversion device formed in FIG. The transparent cover body 7 is softened and a part of the translucent cover body 7 is brought into close contact with the translucent protective plate 8. The translucent protective plate 8 is only required to be optically transparent and more heat resistant than the translucent cover body 7, and includes transparent resins such as glass, polycarbonate, and PET (polyethylene terephthalate). As described above, the photoelectric conversion device shown in FIG. 2 is provided with a large number of granular photoelectric conversion bodies that perform photoelectric conversion on one main surface of a substrate serving as one electrode, and the large number of granular photoelectric conversions. A step of providing an insulator layer at a lower portion between the bodies and forming the other electrode along the outer surface of the granular photoelectric converter and the insulator layer on the upper part of the multiple granular photoelectric converters and the insulator layer And a step of sequentially arranging a translucent resin film on the other electrode, a translucent filler having a refractive index lower than that of the resin film, and a translucent protective plate, and laminating. It can be easily produced by performing.

  3 is a cross-sectional view showing a state in which an optically transparent filler 10 is provided between the translucent cover body 7 and the translucent protective plate 8 of the photoelectric conversion device shown in FIG. . Here, it is desirable that the refractive index relationship between the translucent cover body 7 and the filler 10 is smaller than that of the translucent cover body 7. When the incident light energy enters the translucent cover body 7 through the filler 10, the light energy can be refracted toward the granular crystal semiconductor 2 and taken into the granular crystal semiconductor 2. For example, when the translucent cover body 7 is EVA (n = 1.49), polyvinylidene fluoride (n = 1.42), silicone resin (n = 1.43) or the like is used. As the formation method, a transparent filler 10 is sandwiched between the translucent cover body 7 and the translucent protective plate 8 of the photoelectric conversion device formed in FIG. Before forming the transparent cover body 7, the film-like transparent cover body 7, the film-like transparent filler 10 and the transparent protective plate 8 are sequentially stacked on the transparent conductive layer 5 of the photoelectric conversion device and laminated with a laminator. To do.

  In FIG. 2, the grain size of the granular crystal semiconductor 2 may vary somewhat, and the back surface of the translucent protective plate 8 also has minute undulations. In some cases, it may be difficult to make a part of the translucent cover body 7 at the top of the semiconductor 2 closely contact. Therefore, as shown in FIG. 4, a translucent buffer layer 11 and a translucent resin film 12 are provided between the translucent cover body 7 and the translucent protective plate 8.

  The translucent buffer layer 11 has a function of absorbing the variation in the grain size of the granular crystal semiconductor 2 and the minute undulations on the back surface of the translucent protective plate 8, is optically transparent, and has a softening temperature. Any material may be used as long as it is equal to or lower than that of the body 7, and is made of, for example, acrylic, polyethylene, EVA (ethylene vinyl acetate), silicone resin, or other transparent thermoplastic resin.

  The translucent resin film 12 has a role of maintaining the air layer 9 so that the light-transmitting buffer layer 11 softened at the time of module formation flows and the air layer 9 is not filled with the material of the light-transmitting buffer layer 11. Any material that is optically transparent and has a softening temperature higher than that of the light-transmitting cover body 7 and the light-transmitting buffer layer 11 may be used, for example, PET (polyethylene terephthalate) or a fluorine resin.

  As these forming methods, a translucent resin film 12, a translucent buffer layer 11, and a translucent protective plate 8 are sequentially placed on the translucent cover body 7 of the photoelectric conversion device formed in FIG. By heating with a laminator while applying vacuum pressure, the translucent cover body 7 is softened and a part thereof is brought into close contact with the translucent resin film 12, and the translucent buffer layer 11 is softened to translucent resin film. Absorbs variations in height between 12 and the translucent protective plate 8.

  Furthermore, in order to further stabilize the contact between the translucent cover 7 at the top of the granular crystal semiconductor 2 and the translucent resin film 12 in FIG. 4, as shown in FIG. The second buffer layer 13 made of the same material as the translucent cover body 7 is provided on the surface in contact with the translucent cover body 7. As the formation method, in the formation method shown in the description of FIG. 4, the translucent cover body 7 as the second buffer layer 13 is formed on the surface of the translucent resin film 12 in contact with the translucent cover body 7 in advance. It may be formed by coating the same material.

  In addition, you may provide the filler 14 and the weather resistant material 15 as shown in FIG. 4 or FIG. 5 in the back surface of the photoelectric conversion apparatus of this invention. The filler 14 may be a thermoplastic resin, and is made of, for example, acrylic, polyethylene, EVA (ethylene vinyl acetate), silicone resin, or other transparent thermoplastic resin. The weather-resistant material 15 only needs to be made of a weather-resistant material. For example, fluorine such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), poly-trifluoroethylene chloride (PCTFE), etc. It consists of a resin, a resin such as polyethylene terephthalate (PET), a sheet laminated with an aluminum foil or a metal oxide film using these resins, a metal sheet such as glass or stainless steel, or the like.

  Next, a more specific example of the photoelectric conversion device of the present invention will be described.

  A sample prepared as follows was used. The silicon particles were bonded to the aluminum alloy by heating p-type silicon particles having a diameter of about 0.2 to 0.6 mm on an aluminum substrate at a temperature of 577 ° C. or higher, which is the eutectic temperature of aluminum and silicon, for about 10 minutes. An insulator layer 3 was filled thereon. Thereafter, the upper surface of the p-type silicon particles is washed, and a mixed crystal semiconductor layer 4 of n-type crystalline silicon and amorphous silicon is formed on the silicon particles 2 and the insulator layer 3 to a thickness of 300 nm. An ITO film having a thickness of 80 nm was formed as the transparent conductive layer 5.

As described above, the photoelectric conversion efficiency of the photoelectric conversion device manufactured by changing the projected area ratio of the silicon particles to the area of the substrate was measured and set as an initial value. Then, place it on a 120 ° C hot plate, place an EVA film with a thickness of 50μm on the transparent conductive layer 5, and apply hot air of 200 ° C with a dryer to form a transparent material layer along the shape of the transparent conductive layer 5 The photoelectric conversion efficiency was measured. Table 1 shows changes when the photoelectric conversion efficiency at that time is an initial value of 1.

  In Comparative Examples 1-1 and 1-2, changes in photoelectric conversion efficiency were both as small as 1.02. When the appearance was confirmed, there was a part where the surface of the transparent material layer was flat, and since the projected area ratio of the silicon particles to the area of the substrate was as small as less than 80%, a part where the surface of the transparent material layer was flat was created. It is considered that the light energy incident on the gaps between the silicon grains is reflected as it is and released outside the photoelectric conversion device, so that the contribution of efficiency is small.

  On the other hand, Samples 1, 2 and 3 showed large changes in photoelectric conversion efficiency. When the appearance was confirmed, it is considered that the surface of the transparent material layer observed in Comparative Example 1 was not recognized as a flat portion, and the light energy incident on the gap between the silicon particles was efficiently taken into the silicon particles.

Similarly to Example 1, the photoelectric conversion efficiency of a photoelectric conversion device formed with a projected area ratio of silicon particles to the substrate area of 85% (without a transparent material layer) was measured and used as an initial value. Then, a 3 mm thick glass plate or a 0.5 mm thick PET sheet was placed on the transparent material layer as a translucent protective plate, and the photoelectric conversion efficiency was measured (Comparative Examples 2 and 3). Next, the transparent protective layer is placed on the transparent material layer and heated up to 120 ° C. while applying pressure so that the back surface of the transparent protective plate and a part of the transparent material on the top of the silicon particles are in close contact with each other. Samples were prepared and the photoelectric conversion efficiency was measured (Examples 4 and 5). Table 2 shows changes in the photoelectric conversion efficiency measured as described above when the initial value is 1.

  In Comparative Examples 2 and 3, the photoelectric conversion efficiency decreased in proportion to the reflectance of the translucent protective plate. On the other hand, in Samples 4 and 5, the decrease rate of the photoelectric conversion efficiency was smaller than that of the comparative example. This is presumably because reflection at the interface of the back surface of the translucent protective plate was reduced by bringing the back surface of the translucent protective plate into close contact with a part of the transparent material at the top of the silicon particles.

Further, the photoelectric conversion efficiency of the photoelectric conversion device manufactured with the projected area ratio of silicon particles to the area of the substrate as described above being 85% was measured and set as an initial value. Then, an EVA film with a thickness of 50 μm as a transparent material on the transparent conductive layer, a polyvinylidene fluoride sheet with a thickness of 0.4 mm as a transparent filler, and a glass plate with a thickness of 3 mm as a translucent protective plate or a PET sheet with a thickness of 0.5 mm are sequentially formed. A sample was prepared by laminating with a laminator, and the photoelectric conversion efficiency was measured (samples 6 and 7). Table 3 shows changes when the photoelectric conversion efficiency at that time is an initial value of 1.

  In both samples 6 and 7, the photoelectric conversion efficiency is improved from the initial value, and the refractive index of the transparent filler is made smaller than the refractive index of the transparent material, so that the light energy incident on the gap between the silicon particles is taken into the silicon particles. This is thought to be due to this.

  The photoelectric conversion efficiency of a photoelectric conversion device manufactured as in Example 1 with a projected area ratio of silicon particles to the substrate area of 85% was measured and used as an initial value. Thereafter, a xylene solution of EVA is applied onto the transparent conductive layer 5 of the photoelectric conversion device, and is placed on a hot plate at 120 ° C. to evaporate xylene, whereby the translucent cover body 7 is formed along the shape of the transparent conductive layer 5. Formed.

  Next, a 3 mm thick glass plate as the translucent protective plate 8, 0.8 mm thick EVA as the translucent buffer layer 11, 0.5 mm thick PET sheet as the translucent resin film 12, translucent cover The photoelectric conversion device having the body 7 (the light receiving surface is the glass plate side), 0.4 mm thick EVA, PET / metal oxide film / weather-resistant material 15 formed by laminating PET, and then laminating with a laminator Sample 8 was designated.

Further, in the same manner as the sample 8, a sample in which the light-transmitting buffer layer 11 and the light-transmitting resin film 12 were not used was prepared and used as sample 9. Table 4 shows the change when the photoelectric conversion efficiency of the above sample was measured and the photoelectric conversion efficiency at that time was set to 1 as the initial value.

  In Sample 9, the rate of change in photoelectric conversion efficiency was 0.94, and the appearance was confirmed. As a result, the back surface of the translucent protective plate 8 and the translucent cover body 7 on the top of the granular crystal semiconductor 2 were not in contact with silicon particles ( It is considered that a loss of light occurred at a portion where the granular crystal semiconductor 2) was partially present and the translucent cover body 7 was not in contact.

  On the other hand, Sample 8 had a small rate of change in photoelectric conversion efficiency. When the external appearance was confirmed, the silicon particles that were not in contact with the translucent cover body 7 seen in the sample 9 were not seen, and the translucent cover body 7 at the top of all the silicon particles was formed on the translucent resin film 12. This is considered to be because the light incident on the gap between the silicon particles was efficiently taken into the silicon particles.

  The photoelectric conversion efficiency of a photoelectric conversion device manufactured as in Example 1 with a projected area ratio of silicon particles to the substrate area of 85% was measured and used as an initial value. Thereafter, a xylene solution of EVA is applied onto the transparent conductive layer 5 of the photoelectric conversion device, and is placed on a hot plate at 120 ° C. to evaporate xylene, whereby the translucent cover body 7 is formed along the shape of the transparent conductive layer 5. Formed.

  Next, a glass plate having a thickness of 3 mm as the translucent protective plate 8, an EVA having a thickness of 0.8 mm as the translucent buffer layer 11, and a side in contact with the translucent cover body 7 as the translucent resin film 12. 0.5 mm thick PET sheet coated with 30 μm thick EVA as the second buffer layer 13 on the surface, a photoelectric conversion device having a translucent cover 7 (the light receiving surface is on the glass plate side), 0.4 mm thick A weather-resistant material 15 formed by laminating EVA and PET / metal oxide film / PET was sequentially placed and laminated with a laminator to obtain sample 10. Table 4 shows the changes when the photoelectric conversion efficiency of the above samples was measured and the photoelectric conversion efficiency at that time was set to an initial value of 1.

  Sample 10 had a smaller rate of change in photoelectric conversion efficiency than sample 8. When the appearance was confirmed, sample 8 had variations in the area of the contact surface between translucent cover 7 and translucent resin film 12. On the other hand, in the sample 10, the area of the contact surface between the translucent cover 7 and the translucent resin film 12 is relatively stable, and light incident on the gap between the silicon particles is more efficiently taken into the silicon particles. This is thought to be due to this.

  From the above, according to the photoelectric conversion device of the present invention, it was possible to improve the conversion efficiency with a structure that maintains reliability, and it was confirmed that a higher-performance photoelectric conversion device can be manufactured.

It is sectional drawing which shows one Embodiment of the photoelectric conversion apparatus of this invention. It is sectional drawing which shows other embodiment of the photoelectric conversion apparatus of this invention. It is sectional drawing which shows other embodiment of the photoelectric conversion apparatus of this invention. It is sectional drawing which shows other embodiment of the photoelectric conversion apparatus of this invention. It is sectional drawing which shows other embodiment of the photoelectric conversion apparatus of this invention. It is sectional drawing which shows the conventional photoelectric conversion apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... First conductive type granular crystal semiconductor 3 ... Insulator layer 4 ... Reverse conductive type semiconductor layer 5 ... Transparent conductive layer 6 ... Aluminum and granular of substrate Alloy layer 7 of silicon of crystalline semiconductor ... Light transmissive cover body 8 Light transmissive protective plate 9 Air layer
10 ... Transparent filler
11 ... Translucent buffer layer
12 ... Translucent resin film
13 ... Second buffer layer
14 ... Filler
15 ・ ・ ・ Weatherproof material
21 ・ ・ ・ Granular crystal semiconductor with the first conductivity type at the center
22 ... Reverse-conducting outer shape of granular crystal semiconductor
23 ... 1st aluminum foil
24 ・ ・ ・ Insulator layer
25 ・ ・ ・ Metal joint
26 ... Second aluminum foil
27 ... Spherical lens

Claims (8)

A large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed on one main surface of a substrate that serves as one electrode, and an insulating layer is provided below the multiple granular photoelectric conversion bodies. On the top of each granular photoelectric converter and on the insulator layer, the other electrode is provided along the surfaces of the granular photoelectric converter and the insulator layer, and on the other electrode along the surface thereof. A photoelectric conversion device comprising a light-transmitting cover body. The photoelectric conversion device according to claim 1, wherein the translucent cover body is a resin film. 3. The photoelectric conversion device according to claim 1, wherein the translucent protective plate is disposed so as to be in contact with a portion of the translucent cover body located at a top portion of the granular photoelectric conversion body. 4. The photoelectric device according to claim 3, wherein a translucent filler having a lower refractive index than that of the translucent cover body is filled between the translucent cover body and the translucent protective plate. Conversion device. The translucent cover body is made of a thermoplastic material, and a translucent resin film, a translucent buffer layer made of a thermoplastic material, and a translucent protective plate are sequentially laminated on the translucent cover body. The photoelectric conversion device according to claim 1. 6. The photoelectric conversion device according to claim 5, wherein the translucent resin film has a surface on the side in contact with the translucent cover body covered with the same thermoplastic material as the translucent cover body. . A large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed on one main surface of a substrate that serves as one electrode, and an insulating layer is provided below the multiple granular photoelectric conversion bodies. A step of providing the other electrode along the surface of the granular photoelectric conversion body and the insulator layer on the upper part of the granular photoelectric conversion body and the insulator layer, and translucency on the other electrode And a step of deforming the resin film along the surface of the other electrode by heating the resin film at a temperature not lower than the softening point. A large number of granular photoelectric conversion bodies that perform photoelectric conversion are disposed on one main surface of a substrate that serves as one electrode, and an insulating layer is provided below the multiple granular photoelectric conversion bodies. A step of providing the other electrode along the surfaces of the granular photoelectric conversion body and the insulator layer on the upper part of the granular photoelectric conversion body and on the insulator layer; A step of providing a translucent resin film along with a translucent filler having a refractive index lower than that of the resin film on the resin film, and the top of the granular photoelectric conversion body of the resin film. And a step of disposing a translucent protective plate so as to be in contact with the portion to be performed.

Images