KR20110073090A - A method for manufacturing solar cells using silicon balls and the solar cells manufactured by the same - Google Patents

Abstract

PURPOSE: A method for manufacturing a solar cell using silicon balls and the solar cell manufactured by the same are provided to improve the efficiency of the silicon balls using a hetero junction structure. CONSTITUTION: A first substrate with one or more grooves is prepared. A first type dopant doped silicon ball(420) is loaded in the groove of the first substrate. A first electrode layer is formed at the lower side of the first substrate to be in contact with the silicon ball. An intrinsic first silicon layer(430) is stacked on the silicon ball. A second type dopant doped second silicon layer is stacked on the first silicon layer. A second electrode layer(450) is stacked on a transparent second substrate. The second substrate is combined to be in contact with the second silicon layer.

Description

A method for manufacturing solar cells using silicon balls and the solar cells manufactured by the same}

The present invention relates to a method for manufacturing a solar cell using a silicon granule and a solar cell manufactured thereby, and more particularly, a silicon which can be easily manufactured at low cost without being based on an expensive silicon substrate manufactured by a complicated process. By using the granules, it is economical, and furthermore, it is possible to improve the efficiency of the silicon granules and at the same time improve the mechanical stability of the silicon granules, and also to omit the subsequent polishing process of the silicon granules, The present invention relates to a solar cell manufacturing method using a silicon particulate, and a solar cell manufactured thereby, which is capable of producing a solar cell using a fine particle.

Solar cells are of great interest as future energy sources. Although many kinds of solar cells are being developed, bulk silicon solar cells currently occupy most of the commercial solar cells. These silicon solar cells have been steadily improving in efficiency over the last few decades, and efforts have been made to lower production costs.

Silicon used as a silicon solar cell is a very abundant resource in the daily environment with silicon, but it requires a considerable production cost in making high purity ingots and wafers. Therefore, in the manufacturing cost of the solar cell manufactured on the silicon wafer, the material cost of the silicon wafer is about 50% of the total cost.

Various technologies have been developed to overcome these limitations of existing silicon solar cells. One of these is the technology to make solar cells using spherical silicon (silicon granules) rather than using a very complicated and costly silicon wafer.

1 is a perspective view of a silicon solar cell in a particulate form (hereinafter referred to as a prior art) disclosed in Clean Venture 21 (hereinafter referred to as CV21) in Japan.

Referring to FIG. 1, a plurality of silicon particles 120 spaced at predetermined intervals are mounted in the plurality of condenser lenses 110. The silicon particles consist of an inner p-type silicon particle core and an n-type silicon shell layer surrounding the core.

2 shows a step of manufacturing a silicon particulate based solar cell according to the prior art.

Referring to FIG. 2, an n-type silicon shell layer 220 is formed on a surface of a p-type silicon core core 210, thereby completing a pn junction structure of a silicon solar cell (see (b)). Thereafter, an antireflection film 230 is coated on the surface of the granules (see (c)). According to the prior art, since the silicon core has a pn junction between an inner core and a shell layer, it should have a structure for electrically connecting the core inside the grain to the outside. To this end, the silicon particles are subjected to a polishing process of the particles to expose the core (p-type silicon layer) 210 to the outside (see (d)). Subsequently, electrodes 240a and 240b are formed and connected to the core and shell layers of the exposed silicon particles, respectively (see (e)), and the silicon particles having the electrodes formed thereafter have a predetermined radius of curvature. 250 is provided inside.

However, this technique has a problem that a physical polishing process for the silicon particles is required. That is, in the case where the silicon particles are fine, for example, when the silicon particles having a small diameter are manufactured at a flexible level, the mechanical polishing process of the silicon particles is not only technically difficult, but also increases the overall manufacturing cost. . In addition, the technique has a problem that the effective light exposure area of the silicon particles is very small by the condensing lens below the silicon particles. Furthermore, when the size or radius of curvature of the condensing lens is increased to increase the light efficiency, there is a problem in that the number of silicon particles in which the actual electrons and holes are generated is limited. In addition, in the prior art, since only the lower portion of the silicon particulate is fixed to the substrate, there is a problem that it is vulnerable to physical shocks and the like.

An object of the present invention to solve the above problem is to provide a new solar cell manufacturing method using a silicon grain.

The problem to be solved by the present invention is to provide a solar cell of a novel structure using a silicon particles.

The solar cell manufacturing method according to the present invention and the solar cell produced thereby are economical because they use silicon granules that can be produced simply and at low cost, not based on expensive silicon substrates produced by complex processes. Furthermore, by using a heterojunction structure, it is possible to improve the mechanical stability of the device through a sandwich structure while improving the efficiency of the silicon particles. In addition, since the mechanical polishing process of the silicon particles can be avoided, fine particles of the size can be manufactured and used, and thus the present invention can be applied to a flexible solar cell.

Hereinafter, the present invention will be described using the drawings and preferred embodiments. However, the following description is only for illustrating the present invention, the scope of the present invention is not limited thereto.

3A to 3E are step diagrams of a method of manufacturing a solar cell according to an embodiment of the present invention.

Referring to FIG. 3A, a first substrate 310 is provided, and the first substrate 310 is provided with at least one groove 310a spaced at a predetermined interval. The silicon particles 320 are seated in the grooves 310a. In the present invention, the silicon particles 320 mean a silicon unit in the form of a sphere or a ball, and in the present invention, the first type impurity is the silicon particles ( Doped state 320). In one embodiment of the present invention, the first type impurity is a p type impurity, or vice versa.

The width of the groove 310a is preferably smaller than the level at which the silicon particles 320 are substantially seated in the grooves, that is, the diameter of the silicon particles 320. Furthermore, although various materials may be used for the first substrate 310, it is preferable that the material has a level of heat resistance that does not melt or deform at least at a process temperature of a subsequent deposition process. For example, when the subsequent deposition of the silicon layer is a plasma chemical vapor deposition (PECVD) process, the process temperature is about 200 ℃. At this time, the material of the first substrate that withstands the above process temperature and does not cause deformation, for example, a metal such as aluminum, iron, silver sheet, stainless steel, or a ceramic type such as alumina Can be used as Furthermore, plastics that can withstand high temperatures can be used as the material of the first substrate, for example, PET, PI, PC, etc. can be used as the material of the first substrate. In particular, the solar cell of the flexible silicon granules is possible by another feature of the present invention, which can produce a silicon grain of a fine size without a mechanical polishing process separate from the characteristics of the flexible plastic or metal substrate.

On the other hand, when the low pressure chemical vapor deposition (LPCVD) process is used in addition to the PECVD, the process temperature is performed at a higher temperature than that of PECVD. In this case, when the metal substrate is used as the first substrate, the efficiency is lowered due to diffusion of impurities, melting at high temperatures, and the like, and the assembly process is difficult. Therefore, the material of the metal substrate is limited to a material such as silver. On the other hand, a ceramic-based substrate that can withstand high temperatures can be used as the first substrate in the LPCVD process.

Referring to FIG. 3B, a first electrode layer 330 is stacked on an opposite surface of the first substrate 310 on which the silicon particles 320 are located, that is, the lower portion of the first substrate 310. Since the first electrode layer 330 is a passage through which holes generated from the silicon particles 320 move, the first electrode layer 330 fills the grooves 310a of the first substrate to fill the silicon particles 320. Contact. In the present invention, the first electrode layer 330 not only functions as a conductive passage through which holes flow as in the conventional solar cell, but also the silicon particles 320 are formed on the first substrate 310, that is, the groove of the first substrate. It also functions as a means for fixing to 310a. To this end, an embodiment of the present invention used a conductive paste, for example, a conductive metal paste containing silver and / or aluminum as the first electrode layer 330. The metal paste is in contact with the lower portion of the silicon particles 320 and then sintered in a high temperature sintering process to fix the silicon particles 320 to the first substrate. The following two methods are possible as a method of sintering the metal paste.

The first method is to deposit a silicon particulate in the hole, and then proceed with the deposition process of the subsequent silicon layer, and then apply the first electrode paste to the lower part of the substrate, and then sinter it again. This method is very preferable because only the substrate and silicon are used in the deposition process to minimize contaminants, but there is a problem that the deposition process should be performed in a state where the silicon grains are not physically fixed to the substrate. However, when the low pressure chemical vapor deposition (LPCVD) process is performed, the silicon particles are not fixed because the silicon layer that is evenly laminated on the entire body and the exposed substrate can fix the silicon particles to a predetermined level. The problem can be solved.

Secondly, after the silicon particulates are seated in the holes, the first electrode layer coating and the sintering process thereof are performed. This method has a problem that the sintered metal layer may be a source of contamination in the deposition process, but there is an advantage in that various deposition processes may be performed while the silicon grains are physically fixed to the substrate. However, there is a problem that the sintered metal layer may be a pollution source of the deposition process.

Hereinafter, a process of laminating a silicon layer on a silicon granular body will be described.

Referring to FIG. 3C, a first silicon layer 340 is stacked on the silicon particles 320. In the present invention, the first silicon layer 340 is an intrinsic silicon layer having an equal number of electrons and holes. The technical meaning of the first silicon layer 340 is described in more detail below.

Referring to FIG. 3D, a second type impurity (which is opposite to the first type impurity) is formed on the first silicon layer 340. When the first type is p type, the second type is n type and the first type is different. In the case of n-type, the second silicon layer 350 doped with the second type is p-type) is stacked.

Various methods may be used as the lamination process of the first silicon layer and the second silicon layer, and in the embodiment of the present invention, plasma enhanced CVD or low pressure chemical vapor deposition (LPCVD) is used. The type of the first substrate is limited and selected according to the lamination process method of the silicon layer as described above.

3C and 3D, the intrinsic silicon layer 340 is inserted and placed between the crystalline p-type silicon grain 320 and the amorphous n-type silicon layer 350 to thereby form the crystalline silicon grain. Passivation and prevention of electron-hole recombination at the surface increase the open voltage of the device. That is, the present invention overcomes the disadvantages of the silicon-based solar cell having high efficiency but low efficiency compared to the silicon wafer-based solar cell by applying the heterojunction silicon solar cell to the silicon particle. Silicon granules-based solar cell manufactured according to the present invention further has a low temperature coefficient of less efficiency decrease due to solar heat in daily life, there is an advantage that the power efficiency is excellent.

Referring to FIG. 3E, the second substrate 360 on which the second electrode 370 is stacked is bonded to the silicon particles, that is, the second silicon layer 350. In particular, the second electrode 270 is in contact with the second silicon layer and becomes a conductive passage through which electrons, etc. generated in the second silicon layer flow to the outside. Unlike the prior art in which the inside of the core (core) and the outside (shell) are different from each other and then partially exposed the inside in a physical manner, the present invention provides a structure in which a separate silicon layer is laminated on a silicon body. The p-type silicon and the n-type silicon may be contacted and connected to separate external electrodes without a separate polishing process for connecting the electrodes.

In one embodiment of the present invention, the second electrode 370 and the second substrate 360 are each a glass substrate and a transparent electrode, for example, an indium-tin oxide (ITO) electrode, to which the sun can be irradiated. Can be. This is because the second substrate and the second electrode act as windows for receiving sunlight, and thus the better the transparency, the better the solar cell efficiency.

4A and 4B are cross-sectional views of two types of silicon particulate based unit solar cells, respectively, manufactured according to the method described above, and FIG. 5 is a cross-sectional view of the entire solar cell.

Referring to FIG. 4A, the silicon particles 420 according to the present invention are seated in the grooves 410 a of the first substrate 410, and the silicon particles 420 are filled in the grooves 410 a first electrode layer. 430 is fixed. In one embodiment of the present invention, the silicon particulate 420 is doped with a p-type impurity, which is a first-type impurity, and has a crystalline property. On the upper part of the silicon particles 420, an intrinsic first silicon layer 430 and a second silicon layer 440 doped with n-type impurities, which are second type impurities, are amorphous. This completes a so-called HIT (Heterojunction with Intrinsic Thin-layer) solar cell in which an intrinsic silicon layer is interpolated in a p-n heterojunction interface layer.

The second substrate 460 on which the second electrode layer 450 is coated is contacted and coupled on the second silicon layer 440, so that the silicon solar cell-based unit solar cell device of the present invention is connected to the lower substrate 410. The pinned state is fixed between the upper substrates 460. This configuration of the present invention is distinguished from the conventional silicon particles based solar cell in which the silicon particles are attached only to one surface of the substrate, and this sandwich configuration can effectively solve the problem of the silicon particles being released from the initial seating position by physical impact.

4B is a cross-sectional view of a silicon particles based solar cell having a structure in which another electrode layer is stacked on the silicon particles disclosed in FIG. 4A. Referring to FIG. 4B, similar to FIG. 4A, the silicon particles 420 are seated in the grooves 410 a of the first substrate 410, and the silicon particles 420 are filled in the grooves 410 a. It is fixed by the one electrode layer 430. In one embodiment of the present invention, the silicon particulate 420 is doped with a p-type impurity, which is a first-type impurity, and has a crystalline property. On the upper part of the silicon particles 420, an intrinsic first silicon layer 430 and a second silicon layer 440 doped with n-type impurities, which are second type impurities, are amorphous. However, in the solar cell according to the exemplary embodiment of the present invention, the transparent electrode layer 470 is stacked on the second silicon layer 440, and the transparent electrode layer 470 is not the second silicon layer 440. In contact with the electrode layer stacked on the substrate 460, that is, the second electrode layer 450. In an embodiment of the present invention, the transparent electrode layer 470 and the second electrode layer 450 include the same material, that is, indium-tin oxide (ITO), and the stacking of the transparent electrode layer is formed on the granules by sputtering. Are stacked on. That is, since the second silicon layer 440 on the silicon grain, that is, the amorphous silicon layer has low electrical conductivity, is to solve the problem of not having sufficient function as an electrode, and the transparent electrode layer such as ITO is made of silicon grain. The structure of forming the upper layer of the sieve improves the charge transfer efficiency of the silicon particles.

Referring to FIG. 5, the silicon particles-based solar cell according to the present invention includes a plurality of silicon particles 420 of FIGS. 4A and 4B, and the silicon particles have a structure spaced apart at predetermined intervals.

The present inventors further noted that holes and electrons separated by light in the semiconductor are collected and flow through each electrode, and a charge loss is caused by the resistive element of each electrode. In particular, since the n-type electrode is directed toward the light input side, the indium tin oxide (ITO) electrode is used as the second electrode. However, the electrical conductivity of the ITO transparent electrode is lower than that of the metal. The inventors provide a silicon grain-based solar cell with a novel structure in which a linear electrode is formed on a transparent electrode such as ITO, which is a second electrode.

Hereinafter, this will be described in detail with reference to the accompanying drawings.

6A and 6B are cross-sectional views and plan views, respectively, of a solar cell in which a linear electrode is formed on a transparent electrode according to an embodiment of the present invention.

6A and 6B, the solar cell is seated on the first substrate 310 through the first substrate 310 and the groove 310a having one or more grooves 310a spaced at predetermined intervals. And a silicon particulate 320 doped with a first type impurity. The solar cell is also formed in the lower portion of the first substrate 310 and the groove (310a), the first electrode layer 330 in contact with the silicon particles in the groove and the intrinsic stacked on the silicon particles 320 A first silicon layer 340 and a second silicon layer 350 stacked on the first silicon layer 340 and doped with a second type impurity, which includes the above-described solar cell of the present invention. same.

The solar cell according to another exemplary embodiment of the present invention includes a linear electrode 380 having one side contacting the second silicon layer 340 and the other side bonded to the second electrode 370. . The linear electrode 380 compensates for the low conductivity of the second electrode 370, which is a transparent electrode such as indium tin oxide (ITO). Therefore, in order to maintain transparency of the solar cell, the linear electrode 380 preferably has a predetermined line width and a separation distance. In one embodiment of the invention the line width, ie width, of the linear electrode is about 100 μm, preferably 50 to 150 μm. If the line width is less than the above range, there is a problem that the actual contact area between the particles and the electrode is lowered. On the contrary, if the line width is more than the above range, the transparency of the substrate is reduced.

Since the linear electrode 610 is also in contact with the plurality of silicon particles 620 simultaneously, the conductive path preferably has a separation distance equal to the separation distance of the silicon particles (see FIG. 6B). If the separation distance of the conductive paths and the separation distance of the silicon particles (distance between the center of the particles and the center) are different from each other, the plurality of conductive paths and the plurality of silicon particles may not be contacted at the same time. In an embodiment of the present invention, a silver paste was used as the conductive metal paste, and the silver paste coating method was screen printing. However, when the size of the silicon particles becomes small and the distance between the centers of the particles becomes short, an inkjet method or the like may be used.

The shape of the linear electrode does not necessarily have to be a straight line as a whole as shown in FIG. 6B, and may be variously shaped according to the configuration of the silicon particulate based solar cell.

Figure 6c shows the silicon particles based solar cells are arranged in a honeycomb shape, rather than aligned in a line. In this case, the number of silicon grains that can be seated throughout the substrate increases, thereby increasing the overall efficiency.

Referring to FIG. 6C, the linear electrode 380 according to the exemplary embodiment of the present invention has a shape in which the silicon particles 450 are seated and interconnect the points of contact with the upper substrate. As described above, the silicon particulate solar cell according to the present invention may be configured in various forms on the substrate, and linear electrodes connecting the same at the same time may be formed by a screen printing method, thereby providing excellent efficiency and economy.

As described above, the solar cell manufacturing method and the solar cell according to the present invention are economical because they use silicon granules that can be easily manufactured at low cost, not based on expensive silicon substrates manufactured by a complicated process. Furthermore, by using a heterojunction structure, it is possible to improve the mechanical stability of the device through a sandwich structure while improving the efficiency of the silicon particles. In addition, since the mechanical polishing process of the silicon particles can be avoided, fine particles of the size can be manufactured and used, and thus the present invention can be applied to a flexible solar cell.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited to the above-described embodiments, which can be modified by those skilled in the art to which the present invention pertains. Modifications are possible. Accordingly, the spirit of the invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications will fall within the scope of the invention.

1 is a perspective view of a silicon solar cell in a particulate form (hereinafter referred to as a prior art) disclosed in Clean Venture 21 (hereinafter referred to as CV21) in Japan.

2 shows a step of manufacturing a silicon particulate based solar cell according to the prior art.

3A to 3E are step diagrams of a method of manufacturing a solar cell according to an embodiment of the present invention.

4A and 4B are cross-sectional views of a silicon solar cell-based unit solar cell and a cross-sectional view of an entire solar cell, respectively, manufactured according to the method described above.

5 is a cross-sectional view of a silicon solar cell-based unit solar cell manufactured according to the method described above of the present invention.

6A to 6C are cross-sectional views and plan views, respectively, of a solar cell in which a linear electrode is formed on a transparent electrode according to an embodiment of the present invention.

Claims (21)

Providing a first substrate having one or more grooves spaced at predetermined intervals; Depositing a silicon grain doped with a first type impurity in the groove on the first substrate; Forming a first electrode layer in contact with the silicon particles under the first substrate on which the silicon particles are seated; Depositing an intrinsic first silicon layer on the silicon grains; Stacking a second silicon layer doped with a second type impurity on the first silicon layer; And Bonding a second transparent electrode substrate on which the second electrode layer is laminated on the second silicon layer such that the second electrode layer is in contact with the second silicon layer. Manufacturing method. The method of claim 1, The first electrode layer is in contact with the silicon particles through the grooves, and the silicon particles are fixed to the grooves through the contact, the solar cell manufacturing method using silicon particles. The method of claim 1, The first electrode layer formation may include applying a metal paste including a first electrode layer material on a lower portion of the first substrate; And Sintering the coated metal paste, characterized in that, a solar cell manufacturing method using a silicon grain. The method of claim 3, Sintering of the metal paste is carried out after the lamination process of the second silicon layer, the solar cell manufacturing method using a silicon grain. The method of claim 3, The metal paste is characterized in that it comprises any one or both of silver, aluminum, solar cell manufacturing method using a silicon grain. The method of claim 1, The stacking of the first silicon layer and the second silicon layer is performed by plasma chemical vapor deposition (PECVD) or low pressure chemical vapor deposition (LPCVD) method, solar cell manufacturing method using a silicon grain. The method of claim 6, The first substrate has a melting point equal to or higher than the process temperature of the lamination process of the first silicon layer and the second silicon layer, the solar cell manufacturing method using a silicon grain. The method of claim 1, The second electrode is characterized in that the indium-tin oxide (ITO), characterized in that the solar cell manufacturing method using the silicon particles. The method of claim 8, The indium-tin oxide (ITO) layer is formed on a linear electrode made of a conductive metal material, characterized in that the solar cell manufacturing method using a silicon grain. The method of claim 9, The linear electrode is in contact with the second electrode layer, characterized in that the solar cell manufacturing method using the silicon particles. A solar cell using the silicon particles produced by the method according to any one of claims 1 to 10. A first substrate having one or more grooves spaced at predetermined intervals; A silicon grain seated in the groove and doped with a first type impurity; A first electrode layer provided under the first substrate and contacting the silicon particles through the groove; An intrinsic first silicon layer laminated on the silicon grains; A second silicon layer stacked on the first silicon layer and doped with a second type impurity; A second electrode layer in contact with the second silicon layer; And A solar cell using a silicon particulate, comprising a second substrate provided on the second electrode layer. A first substrate having one or more grooves spaced at predetermined intervals; A silicon grain seated on the first substrate through the groove and doped with a first type impurity; A first electrode layer formed under the first substrate and in the groove and contacting the silicon grains in the groove; An intrinsic first silicon layer laminated on the silicon grains; A second silicon layer stacked on the first silicon layer and doped with a second type impurity; A linear electrode on one side of which is in contact with the second silicon layer and the other side of which is bonded to the second electrode; A second electrode layer having one side bonded to the linear electrode and the other side bonded to a second substrate; And A solar cell using a silicon grain, the second electrode comprising a second substrate provided on one side. A first substrate having one or more grooves spaced at predetermined intervals; A silicon grain seated in the groove and doped with a first type impurity; A first electrode layer provided under the first substrate and contacting the silicon particles through the groove; An intrinsic first silicon layer laminated on the silicon grains; A second silicon layer stacked on the first silicon layer and doped with a second type impurity; A transparent electrode layer laminated on the second silicon layer; A second electrode layer interposed between the transparent electrode layer and a second substrate below and in contact with the second electrode layer; A solar cell using a silicon particulate, characterized in that it comprises a second substrate on which the second electrode layer is laminated. The method according to any one of claims 12 to 14, The first type impurity is a p-type impurity, the second type impurity, n-type impurity, characterized in that the solar cell using silicon particles. The method according to any one of claims 12 to 14, The first substrate is any one selected from the group consisting of aluminum, iron, silver, stainless steel, alumina, PET, PI, PC, solar cell using a silicon grain. The method according to any one of claims 12 to 14, The first electrode is characterized in that any one or both of silver or aluminum, solar cell using a silicon grain. The method according to any one of claims 12 or 13, The second electrode comprises indium-tin oxide (ITO), solar cell using a silicon grain. The method according to any one of claims 12 to 14, The second substrate is a transparent substrate, characterized in that the solar cell using a silicon grain. 15. The method of claim 14, The transparent electrode layer and the second electrode layer is a solar cell using silicon particles, characterized in that the transparent electrode layer containing the same material. The method of claim 20, The transparent electrode layer and the second electrode layer is characterized in that it comprises indium-tin oxide (ITO), solar cell using a silicon grain.

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