WO2008093932A1 - Crystalline silicon thin film solar cell using thermal oxide layer - Google Patents

Crystalline silicon thin film solar cell using thermal oxide layer Download PDF

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Publication number
WO2008093932A1
WO2008093932A1 PCT/KR2007/006724 KR2007006724W WO2008093932A1 WO 2008093932 A1 WO2008093932 A1 WO 2008093932A1 KR 2007006724 W KR2007006724 W KR 2007006724W WO 2008093932 A1 WO2008093932 A1 WO 2008093932A1
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Prior art keywords
electrode
solar cell
thin film
layer
crystalline silicon
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PCT/KR2007/006724
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French (fr)
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Byoung Su Lee
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Siliconfile Technologies Inc.
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Publication of WO2008093932A1 publication Critical patent/WO2008093932A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/036—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
    • H01L31/0392—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
    • H01L31/03921—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate including only elements of Group IV of the Periodic System
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
    • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
    • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
    • H01L31/0465—PV modules composed of a plurality of thin film solar cells deposited on the same substrate comprising particular structures for the electrical interconnection of adjacent PV cells in the module
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a crystalline silicon thin film solar cell, and more particularly, to a crystalline silicon thin film solar cell which achieves insulation between two or more unit cells by using a thermal oxide layer, so that it is possible to easily manufacture an insulating layer and remove defects on a surface of the solar cell.
  • Solar cells may be classified into a bulk type using monocrystalline or poly- crystalline silicon substrates and a thin-film type including thin films are deposited.
  • the cell manufacturing process and the module manufacturing process are not divided but performed as a single process. Therefore, in a manufacturing process of the thin-film type solar cell, dividing cells from each other and electrically connecting the cells to each other oxupy a high percentage of manufacturing costs of the solar cell.
  • FIG. 1 is a view illustrating an electrical connection between cells of a conventional solar cell using an amorphous silicon thin film.
  • an antireflection layer 120 is formed on a transparent substrate
  • TCO transparent conductive oxide
  • the TCO electrode 131 is divided by a laser scriber, and the divided TCO electrode 131 is connected with a first electrode 141.
  • An electricity generation region 151 and a second electrode layer 161 are sequentially formed on the first electrode 141, and a metal layer 171 is connected with the second electrode layer 161.
  • the metal layer 171 is connected with a TCO electrode 132 of an adjacent cell so that adjacent cells are electrically connected.
  • the first electrode 141 and the electricity generation region 151 that electrically contact the metal layer 171 have high electrical resistances, an electricity generation efficiency is not significantly affected.
  • the thin-film type solar cell has a simple structure for the connection.
  • a specific resistance is low as that of a crystalline thin film, an efficiency may decrease due to the connection between the first electrode 141 and the metal layer 171. Therefore, the structure for the connection cannot be used for a crystalline thin film solar cell.
  • FIG. 2 is a view illustrating an electrical connection between cells of a conventional solar cell using a crystalline silicon thin film.
  • an antireflection layer 220 is formed on a transparent substrate
  • a TCO electrode 231 is formed on the antireflection layer 220.
  • a first electrode 241 is connected with the TCO electrode 231, and an electricity generation region 251 and a second electrode 261 are sequentially formed on the first electrode 241.
  • An insulating layer 270 is formed on the second electrode 261 to insulate the first electrode 241, the electricity generation region 251, and the second electrode 261 of each unit cell or the unit cell from an adjacent cell.
  • a portion of the insulating layer 270 is removed by performing etching to expose a portion of the second electrode 261, and a metal layer 280 is formed on the insulating layer 270.
  • portions of an electricity generation region 252 and a second electrode 262 of the adjacent cell are removed by performing etching so that a portion of a first electrode 242 is exposed and connected to the metal layer 280, so that an electrical connection between the cells can be implemented.
  • the insulating layer 270 used in the aforementioned structure may be made of an organic material such as resin.
  • the structure as illustrated in FIG. 2 has advantages in that contact between metal and a semiconductor can be minimized, so that a high efficiency can be obtained.
  • resin having a low melting point is used and a reflow process can be used, so that a manufacturing process can be simplified.
  • the resin having the low melting point is used, so that a thermal process for correcting defects that may occur when the etching is performed after the cells are connected cannot be applied. Disclosure of Invention Technical Problem
  • a crystalline silicon thin film solar cell including two or more unit cells, wherein the unit cell includes: an antireflection layer formed on a transparent substrate; a transparent conductive oxide (TCO) electrode formed on the antireflection layer; a first electrode formed on the TCO electrode; an electricity generation region formed on the first electrode; a second electrode formed on the electricity generation region; an insulating layer which has an opening portion for exposing a portion of the second electrode and is formed to cover a top portion of the second electrode and side surfaces of the first electrode, the electricity generation region, and the second electrode; and a conductive layer electrically connecting the two or more unit cells to each other, and wherein the insulating layer is a thermal oxide layer formed by performing thermal oxidation.
  • TCO transparent conductive oxide
  • a crystalline silicon thin film solar cell uses a thermal oxide layer as an insulating layer for insulating unit cells from each other.
  • the thermal oxide layer is formed by reacting a silicon layer to reactant gas such as oxygen or steam at a high temperature.
  • reactant gas such as oxygen or steam
  • silicon atoms on a surface of a silicon substrate are in a dangling bond state in which some of valence electrons cannot react but are missing neighbors. Electrons participating in the dangling bonds negatively affect operations of a semiconductor.
  • the thermal oxide layer removes the dangling bonds and has a good insulation property, so that the thermal oxide layer is used as a representative passivation layer used for the semiconductor. Therefore, when the thermal oxide layer is applied to the solar cell, the thermal oxide layer can reduce surface recombinations by effectively removing the surface defects, so that an efficiency of the solar cell can be improved.
  • the thin-film type solar cell has a relatively thin (IQM or less) electricity generation region and uses a structure in which electrons and holes generated from light are accumulated at both side surfaces and light transmitted by a rear surface by using a reflection plate is incident onto a cell. Therefore, surface absorption depending on a surface state that oxurs at the surface and the surface recombinations at the surface negatively affect the electricity generation efficiency.
  • FIG. 2 is a view illustrating an electrical connection between cells of a conventional solar cell using a crystalline silicon thin film.
  • FIG. 3 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to an embodiment of the present invention.
  • FIGS. 4 to 6 are views illustrating a manufacturing process of the crystalline silicon thin film solar cell using the thermal oxide insulating layer according to the em- bodiment of the present invention.
  • FIG. 7 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to another embodiment of the present invention. Best Mode for Carrying Out the Invention
  • FIG. 3 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to an embodiment of the present invention.
  • the crystalline silicon thin film solar cell includes an antireflection layer 320 formed on a transparent substrate 310 and a transparent conductive oxide (TCO) electrode 331 formed on the antireflection layer 320.
  • a first electrode 341, an electricity generation region 351, and a second electrode 361 are sequentially formed on the TCO electrode 331.
  • An insulating layer 371 for eclectically insulating a unit cell or the unit cell from an adjacent cell is formed on the second electrode 361 and at side surfaces of the first electrode 341, the electricity generation region 351, and the second electrode 361.
  • a conductive layer 381 is formed on the insulating layer 371.
  • the conductive layer 381 electrically connects the second electrode 361 of the unit cell with a TCO electrode 332 of the adjacent cell.
  • the insulating layer 371 may be a thermal oxide layer formed by performing thermal oxidation. After performing the thermal oxidation, annealing may be performed by using hydrogen gas to remove dangling bonds that cannot react and remain on a surface of the solar cell.
  • FIGS. 4 to 6 are views illustrating a manufacturing process of the crystalline silicon thin film solar cell using the thermal oxide insulating layer according to the embodiment of the present invention.
  • unit cells of a crystalline silicon thin film solar cell are formed. Specifically, an antireflection layer 420 is formed on a transparent substrate, and TCO electrodes 431 and 432 are formed on the antireflection layer 420. First electrodes 441 and 442, electricity generation regions 451 and 452, and second electrodes 461 and 462 are sequentially formed on the divided TCO electrodes 431 and 432, respectively, to form respective unit cells.
  • Insulating layers 471 and 472 are formed on regions of the unit cells contacting the air. Thereafter, opening portions 491 and 492 for exposing portions of the second electrodes 461 and 462 are formed by removing portions of the insulating layers 471 and 472, respectively. A conductive layer is formed on the insulating layers 471 and 472 to electrically connect the second electrode 461 of the unit cell to the TCO electrode 432 of the adjacent cell.
  • the insulating layers 471 and 472 may be oxide layers formed by performing thermal oxidation. After forming the oxide layers, annealing using hydrogen gas may be performed to remove dangling bonds that remain on a silicon surface.
  • FIG. 7 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to another embodiment of the present invention.
  • the crystalline silicon thin film solar cell includes an antireflection layer 520 formed on a transparent substrate 510 and a first electrode 541 formed on the antireflection layer 520.
  • An electricity generation region 551 and a second electrode 561 are sequentially formed on the fist electrode 541.
  • An insulating layer 571 for electrically insulating a unit cell or the unit cell from an adjacent cell is formed on the second de 561 and at side surfaces of the first electrode 541, the electricity generation region 551, and the second electrode 561.
  • an insulating layer 572 is formed at side surfaces of a hole 592 formed through the electricity generation region 552 and the second electrode 562.
  • a conductive layer 581 is formed on the insulating layers 571 and 572.
  • the conductive layer 581 electrically connects the second electrode 561 of the unit cell to a first electrode 542 of the adjacent cell.
  • the first electrode 541 is formed on the antireflection layer 520 without a TCO electrode therebetween, and the second electrode 561 of the unit cell is electrically connected to the first electrode 542 of the adjacent cell through the opening portions 591 and 592.
  • the insulating layers 571 and 572 may be thermal oxide layers formed by performing thermal oxidation. After performing the thermal oxidation, annealing may be performed by using hydrogen gas to remove dangling bonds that cannot react and remain on a surface of the solar cell.
  • insulation between unit cells is implemented by the thermal oxide layer formed by performing thermal oxidation, so that the insulating layer can be easily manufactured, and electron-hole recombination that oxurs on the surface of the solar cell can be effectively removed, thereby increasing an efficiency.
  • thermal oxide layer since a dense structure of the thermal oxide layer is used, a thin film having a uniform thickness can be obtained as compared with a conventional deposition method. In addition, due to thermal stability of the thermal oxide layer, a high temperature process such as hydrogen thermal treatment can be applied after an electrical connection is implemented.

Abstract

Provided is a crystalline silicon thin film solar cell which achieves insulation between two or more unit cells by using a thermal oxide layer. The crystalline silicon thin film solar cell achieves insulation between unit cells by using an oxide layer formed by performing thermal oxidation, and after removing portions of the thermal oxide layer, the unit cells are electrically connected to each other by a conductive layer formed on the thermal oxide layer. An insulating layer of the crystalline silicon thin film solar cell can be easily manufactured and has a good insulation property to increases surface characteristics of the cell, so that the solar cell having a high efficiency can be manufactured.

Description

Description
CRYSTALLINE SILICON THIN FILM SOLAR CELL USING
THERMAL OXIDE LAYER
Technical Field
[1] The present invention relates to a crystalline silicon thin film solar cell, and more particularly, to a crystalline silicon thin film solar cell which achieves insulation between two or more unit cells by using a thermal oxide layer, so that it is possible to easily manufacture an insulating layer and remove defects on a surface of the solar cell. Background Art
[2] A solar cell is referred to as an electricity generation device for generating voltages and currents from light. For electricity generation efficiency, electricity generation efficiency of a unit cell is important. In addition, the efficiency may decrease due to a series resistance that oxurs due to connections between the unit cells, so that efficiency of a module for connecting the cells with each other is also an important factor.
[3] Solar cells may be classified into a bulk type using monocrystalline or poly- crystalline silicon substrates and a thin-film type including thin films are deposited.
[4] In the bulk type, in order to connect cells to form a module, each cell is weld to an aluminum wire, and the cells are interconnected in series by crossing the aluminum wire. In this case, the aluminum has to be thick enough to reduce a resistance caused by the serial connection, and this is performed in a module manufacturing process included in a packing process after manufacturing the cells.
[5] On the other hand, in the thin-film type, generally, the cell manufacturing process and the module manufacturing process are not divided but performed as a single process. Therefore, in a manufacturing process of the thin-film type solar cell, dividing cells from each other and electrically connecting the cells to each other oxupy a high percentage of manufacturing costs of the solar cell.
[6] FIG. 1 is a view illustrating an electrical connection between cells of a conventional solar cell using an amorphous silicon thin film.
[7] Referring to FIG. 1, an antireflection layer 120 is formed on a transparent substrate
110, and a transparent conductive oxide (TCO) electrode 131 is formed on the antireflection layer 120. The TCO electrode 131 is divided by a laser scriber, and the divided TCO electrode 131 is connected with a first electrode 141. An electricity generation region 151 and a second electrode layer 161 are sequentially formed on the first electrode 141, and a metal layer 171 is connected with the second electrode layer 161. The metal layer 171 is connected with a TCO electrode 132 of an adjacent cell so that adjacent cells are electrically connected. Here, since the first electrode 141 and the electricity generation region 151 that electrically contact the metal layer 171 have high electrical resistances, an electricity generation efficiency is not significantly affected.
[8] The thin-film type solar cell has a simple structure for the connection. However, when a specific resistance is low as that of a crystalline thin film, an efficiency may decrease due to the connection between the first electrode 141 and the metal layer 171. Therefore, the structure for the connection cannot be used for a crystalline thin film solar cell.
[9] The crystalline thin film solar cell uses a connection as illustrated in FIG. 2 in order to prevent the decrease in the efficiency.
[10] FIG. 2 is a view illustrating an electrical connection between cells of a conventional solar cell using a crystalline silicon thin film.
[11] Referring to FIG. 2, an antireflection layer 220 is formed on a transparent substrate
210, and a TCO electrode 231 is formed on the antireflection layer 220. A first electrode 241 is connected with the TCO electrode 231, and an electricity generation region 251 and a second electrode 261 are sequentially formed on the first electrode 241. An insulating layer 270 is formed on the second electrode 261 to insulate the first electrode 241, the electricity generation region 251, and the second electrode 261 of each unit cell or the unit cell from an adjacent cell.
[12] A portion of the insulating layer 270 is removed by performing etching to expose a portion of the second electrode 261, and a metal layer 280 is formed on the insulating layer 270. In addition, portions of an electricity generation region 252 and a second electrode 262 of the adjacent cell are removed by performing etching so that a portion of a first electrode 242 is exposed and connected to the metal layer 280, so that an electrical connection between the cells can be implemented. Here, generally, the insulating layer 270 used in the aforementioned structure may be made of an organic material such as resin.
[13] The structure as illustrated in FIG. 2 has advantages in that contact between metal and a semiconductor can be minimized, so that a high efficiency can be obtained. In addition, resin having a low melting point is used and a reflow process can be used, so that a manufacturing process can be simplified. However, there is a problem in that the resin having the low melting point is used, so that a thermal process for correcting defects that may occur when the etching is performed after the cells are connected cannot be applied. Disclosure of Invention Technical Problem
[14] The present invention provides a crystalline silicon thin film solar cell including two or more unit cells which achieves insulation between the unit cells by using a thermal oxide layer, so that it is possible to easily manufacture an insulating layer and remove defects on a surface of the solar cell. Technical Solution
[15] According to an aspect of the present invention, there is provided a crystalline silicon thin film solar cell including two or more unit cells, wherein the unit cell includes: an antireflection layer formed on a transparent substrate; a transparent conductive oxide (TCO) electrode formed on the antireflection layer; a first electrode formed on the TCO electrode; an electricity generation region formed on the first electrode; a second electrode formed on the electricity generation region; an insulating layer which has an opening portion for exposing a portion of the second electrode and is formed to cover a top portion of the second electrode and side surfaces of the first electrode, the electricity generation region, and the second electrode; and a conductive layer electrically connecting the two or more unit cells to each other, and wherein the insulating layer is a thermal oxide layer formed by performing thermal oxidation.
[16] According to another aspect of the present invention, there is provided a crystalline silicon thin film solar cell including two or more unit cells, wherein the unit cell includes: an antireflection layer formed on a transparent substrate; a first electrode formed on the antireflection layer; an electricity generation region formed on the first electrode; a second electrode formed on the electricity generation region; an insulating layer which has opening portions for exposing portions of the first and second electrodes and is formed to cover upper portions of the first and second electrode and side surfaces of the first electrode, the electricity generation region, and the second electrode; and a conductive layer electrically connecting the two or more unit cells to each other, wherein the insulating layer is a thermal oxide layer formed by performing thermal oxidation.
[17] A crystalline silicon thin film solar cell according to the present invention uses a thermal oxide layer as an insulating layer for insulating unit cells from each other. The thermal oxide layer is formed by reacting a silicon layer to reactant gas such as oxygen or steam at a high temperature. In general, silicon atoms on a surface of a silicon substrate are in a dangling bond state in which some of valence electrons cannot react but are missing neighbors. Electrons participating in the dangling bonds negatively affect operations of a semiconductor. The thermal oxide layer removes the dangling bonds and has a good insulation property, so that the thermal oxide layer is used as a representative passivation layer used for the semiconductor. Therefore, when the thermal oxide layer is applied to the solar cell, the thermal oxide layer can reduce surface recombinations by effectively removing the surface defects, so that an efficiency of the solar cell can be improved.
[18] The thin-film type solar cell has a relatively thin (IQM or less) electricity generation region and uses a structure in which electrons and holes generated from light are accumulated at both side surfaces and light transmitted by a rear surface by using a reflection plate is incident onto a cell. Therefore, surface absorption depending on a surface state that oxurs at the surface and the surface recombinations at the surface negatively affect the electricity generation efficiency.
[19] Accordingly, surface processing is a core technology for increasing the electricity generation efficiency of the thin-film type solar cell. In addition, on the surface of the solar cell, the dangling bonds exist, and strong absorption of the most of wavelengths oxurs, so that removing the dangling bonds is necessary to increase the efficiency.
[20] For this, in general, technologies such as deposition of silicon carbide (SiC), silicon nitride (SiN), or silicon dioxide (SiO 2) thin films, hydrogen thermal treatment, and the like are used. In the present invention, the deposition of SiC, SiN, and the like that requires additional deposition apparatuses is not performed, but an SiO2 layer formed by performing thermal oxidation that can be used with the hydrogen thermal treatment is used. Brief Description of the Drawings
[21] FIG. 1 is a view illustrating an electrical connection between cells of a conventional solar cell using an amorphous silicon thin film.
[22] FIG. 2 is a view illustrating an electrical connection between cells of a conventional solar cell using a crystalline silicon thin film.
[23] FIG. 3 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to an embodiment of the present invention.
[24] FIGS. 4 to 6 are views illustrating a manufacturing process of the crystalline silicon thin film solar cell using the thermal oxide insulating layer according to the em- bodiment of the present invention.
[25] FIG. 7 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to another embodiment of the present invention. Best Mode for Carrying Out the Invention
[26] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the attached drawings.
[27] FIG. 3 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to an embodiment of the present invention.
[28] Referring to FIG. 3, the crystalline silicon thin film solar cell according to the embodiment includes an antireflection layer 320 formed on a transparent substrate 310 and a transparent conductive oxide (TCO) electrode 331 formed on the antireflection layer 320. A first electrode 341, an electricity generation region 351, and a second electrode 361 are sequentially formed on the TCO electrode 331. An insulating layer 371 for eclectically insulating a unit cell or the unit cell from an adjacent cell is formed on the second electrode 361 and at side surfaces of the first electrode 341, the electricity generation region 351, and the second electrode 361.
[29] After removing a portion of the insulating layer 371, a conductive layer 381 is formed on the insulating layer 371. The conductive layer 381 electrically connects the second electrode 361 of the unit cell with a TCO electrode 332 of the adjacent cell.
[30] Here, the insulating layer 371 may be a thermal oxide layer formed by performing thermal oxidation. After performing the thermal oxidation, annealing may be performed by using hydrogen gas to remove dangling bonds that cannot react and remain on a surface of the solar cell.
[31] FIGS. 4 to 6 are views illustrating a manufacturing process of the crystalline silicon thin film solar cell using the thermal oxide insulating layer according to the embodiment of the present invention.
[32] Referring to FIGS. 4 to 6, first, unit cells of a crystalline silicon thin film solar cell are formed. Specifically, an antireflection layer 420 is formed on a transparent substrate, and TCO electrodes 431 and 432 are formed on the antireflection layer 420. First electrodes 441 and 442, electricity generation regions 451 and 452, and second electrodes 461 and 462 are sequentially formed on the divided TCO electrodes 431 and 432, respectively, to form respective unit cells.
[33] Insulating layers 471 and 472 are formed on regions of the unit cells contacting the air. Thereafter, opening portions 491 and 492 for exposing portions of the second electrodes 461 and 462 are formed by removing portions of the insulating layers 471 and 472, respectively. A conductive layer is formed on the insulating layers 471 and 472 to electrically connect the second electrode 461 of the unit cell to the TCO electrode 432 of the adjacent cell.
[34] Here, the insulating layers 471 and 472 may be oxide layers formed by performing thermal oxidation. After forming the oxide layers, annealing using hydrogen gas may be performed to remove dangling bonds that remain on a silicon surface.
[35] FIG. 7 is a view schematically illustrating a structure of a crystalline silicon thin film solar cell using a thermal oxide insulating layer according to another embodiment of the present invention.
[36] Referring to FIG. 7, the crystalline silicon thin film solar cell according to the current embodiment includes an antireflection layer 520 formed on a transparent substrate 510 and a first electrode 541 formed on the antireflection layer 520. An electricity generation region 551 and a second electrode 561 are sequentially formed on the fist electrode 541. An insulating layer 571 for electrically insulating a unit cell or the unit cell from an adjacent cell is formed on the second de 561 and at side surfaces of the first electrode 541, the electricity generation region 551, and the second electrode 561. In addition, an insulating layer 572 is formed at side surfaces of a hole 592 formed through the electricity generation region 552 and the second electrode 562. After removing portions of the insulating layers 571 and 572, a conductive layer 581 is formed on the insulating layers 571 and 572. The conductive layer 581 electrically connects the second electrode 561 of the unit cell to a first electrode 542 of the adjacent cell.
[37] Specifically, in this structure, the first electrode 541 is formed on the antireflection layer 520 without a TCO electrode therebetween, and the second electrode 561 of the unit cell is electrically connected to the first electrode 542 of the adjacent cell through the opening portions 591 and 592.
[38] Here, the insulating layers 571 and 572 may be thermal oxide layers formed by performing thermal oxidation. After performing the thermal oxidation, annealing may be performed by using hydrogen gas to remove dangling bonds that cannot react and remain on a surface of the solar cell.
[39] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. Industrial Applicability
[40] Accordingly, in the crystalline silicon thin film solar cell, insulation between unit cells is implemented by the thermal oxide layer formed by performing thermal oxidation, so that the insulating layer can be easily manufactured, and electron-hole recombination that oxurs on the surface of the solar cell can be effectively removed, thereby increasing an efficiency.
[41] In addition, since a dense structure of the thermal oxide layer is used, a thin film having a uniform thickness can be obtained as compared with a conventional deposition method. In addition, due to thermal stability of the thermal oxide layer, a high temperature process such as hydrogen thermal treatment can be applied after an electrical connection is implemented.

Claims

Claims
[1] A crystalline silicon thin film solar cell including two or more unit cells, wherein the unit cell comprises: an antireflection layer formed on a transparent substrate; a TCO (transparent conductive oxide) electrode formed on the antireflection layer; a first electrode formed on the TCO electrode; an electricity generation region formed on the first electrode; a second electrode formed on the electricity generation region; an insulating layer which has an opening portion for exposing a portion of the second electrode and is formed to cover a top portion of the second electrode and side surfaces of the first electrode, the electricity generation region, and the second electrode; and a conductive layer electrically connecting the two or more unit cells to each other, and wherein the insulating layer is a thermal oxide layer formed by performing thermal oxidation.
[2] The crystalline silicon thin film solar cell of claim 1, wherein the conductive layer is formed on and at a side surface of the insulating layer and electrically connects the second electrode of the unit cell to a TCO electrode of an adjacent cell.
[3] A crystalline silicon thin film solar cell including two or more unit cells, wherein the unit cell comprises: an antireflection layer formed on a transparent substrate; a first electrode formed on the antireflection layer; an electricity generation region formed on the first electrode; a second electrode formed on the electricity generation region; an insulating layer which has opening portions for exposing portions of the first and second electrodes and is formed to cover upper portions of the first and second electrode and side surfaces of the first electrode, the electricity generation region, and the second electrode; and a conductive layer electrically connecting the two or more unit cells to each other, wherein the insulating layer is a thermal oxide layer formed by performing thermal oxidation.
[4] The crystalline silicon thin film solar cell of claim 3, wherein the conductive layer is formed on and at a side surface of the insulating layer and electrically connects the second electrode of the unit cell to a first electrode of an adjacent cell.
PCT/KR2007/006724 2007-01-30 2007-12-21 Crystalline silicon thin film solar cell using thermal oxide layer WO2008093932A1 (en)

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KR1020070009213A KR100819350B1 (en) 2007-01-30 2007-01-30 Crystalline silicon thin film solar cell using a thermal oxidation film
KR10-2007-0009213 2007-01-30

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EP2341546A3 (en) * 2009-12-29 2013-01-09 Auria Solar Co., Ltd. Solar cell and manufacturing method thereof
EP2490260A3 (en) * 2011-02-16 2013-09-25 Auria Solar Co., Ltd. Color building-integrated photovoltaic (BIPV) panel

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US6245691B1 (en) * 1998-05-29 2001-06-12 Taiwan Semiconductor Manufacturing Company Ozone-teos method for forming with attenuated surface sensitivity a silicon oxide dielectric layer upon a thermally oxidized silicon substrate layer
US6303963B1 (en) * 1998-12-03 2001-10-16 Semiconductor Energy Laboratory Co., Ltd. Electro-optical device and semiconductor circuit
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US6187448B1 (en) * 1997-07-24 2001-02-13 Evergreen Solar, Inc. Encapsulant material for solar cell module and laminated glass applications
US6245691B1 (en) * 1998-05-29 2001-06-12 Taiwan Semiconductor Manufacturing Company Ozone-teos method for forming with attenuated surface sensitivity a silicon oxide dielectric layer upon a thermally oxidized silicon substrate layer
US6303963B1 (en) * 1998-12-03 2001-10-16 Semiconductor Energy Laboratory Co., Ltd. Electro-optical device and semiconductor circuit
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2341546A3 (en) * 2009-12-29 2013-01-09 Auria Solar Co., Ltd. Solar cell and manufacturing method thereof
EP2490260A3 (en) * 2011-02-16 2013-09-25 Auria Solar Co., Ltd. Color building-integrated photovoltaic (BIPV) panel

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