WO2012043929A1 - Method for fabricating high efficiency flexible compound semiconductor thin film solar cell with chalcopyrite system - Google Patents

Method for fabricating high efficiency flexible compound semiconductor thin film solar cell with chalcopyrite system Download PDF

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WO2012043929A1
WO2012043929A1 PCT/KR2010/008479 KR2010008479W WO2012043929A1 WO 2012043929 A1 WO2012043929 A1 WO 2012043929A1 KR 2010008479 W KR2010008479 W KR 2010008479W WO 2012043929 A1 WO2012043929 A1 WO 2012043929A1
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layer
solar cell
thin film
compound semiconductor
cell structure
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PCT/KR2010/008479
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French (fr)
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Yonkil Jeong
Seung-Hyeon Moon
Yong-Tak Lee
Hee-Sang Shim
Chang Young Park
Chae-Woong Kim
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Gwangju Institute Of Science And Technology
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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
    • H01L31/0248—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
    • H01L31/03923—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 AIBIIICVI compound materials, e.g. CIS, CIGS
    • 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
    • H01L31/06—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 characterised by potential barriers
    • H01L31/072—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 characterised by potential barriers the potential barriers being only of the PN heterojunction type
    • H01L31/0749—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 characterised by potential barriers the potential barriers being only of the PN heterojunction type including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1892—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof methods involving the use of temporary, removable substrates
    • H01L31/1896—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof methods involving the use of temporary, removable substrates for thin-film semiconductors
    • 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
    • Y02E10/541—CuInSe2 material PV cells

Definitions

  • the present disclosure relates to a method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor, and more particularly, to a method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor, which utilizes heterogeneous integration technology and includes, as a diffusion barrier and a dielectric, a binary compound semiconductor GaAs thin film having excellent thermal expansion coefficient selectivity.
  • Group I-III-VI 2 chalcopyrite-based compound semiconductors such as CIGS(Cu(In,Ga,Al)(Se,S)), have a direct transition type energy band gap and the highest light absorption coefficient, 1 ⁇ 10 5 cm -1 , among known semiconductors. Therefore, such compound semiconductors enable fabrication of a high-efficiency solar cell even when used as a thin film with a thickness of 1 to 2 micrometers. In addition, they have excellent long-term electro-optical stability and radiation hardness, so that they may be useful for universal solar cell applications as well as ground power supply applications.
  • CIGS thin film solar cell modules fabricated based on low carbon steel forming a diffusion barrier via an expensive vacuum deposition process have an efficiency of about 16%, which is the highest efficiency level as compared to other CIGS thin film solar cells using a flexible substrate.
  • the aforementioned thin film solar cells still have problems in that they frequently cause separation of CIGS films, including cracking of a lower electrode, and they have an insufficient efficiency as compared to the efficiency (20.7%) of CIGS thin film solar cells fabricated on a soda lime glass substrate.
  • the present disclosure is directed to providing a method for fabricating a high-efficiency flexible thin film solar cell using a CIGS-based compound semiconductor, which realizes improved efficiency of CIGS thin film solar cell, prevents separation of a CIGS film and cracking of a lower electrode, and shows improved process efficiency.
  • the present disclosure is also directed to providing a high-efficiency flexible thin film solar cell using a CIGS-based compound semiconductor, which prevents separation of a CIGS film and cracking of a lower electrode.
  • the solar cell structure may include a molybdenum layer for a lower electrode, a CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer, a CdS buffer layer, an undoped ZnO window layer, a n-doped ZnO window layer, an anti-reflective layer, and a nickel and aluminum layer for an upper electrode, stacked successively on the diffusion barrier dielectric.
  • CIGS Cu(In,Ga,Al)(Se,S)
  • the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer may have a band gap of 1.04 to 3.49 eV.
  • the sacrificial layer may include an aluminum-containing ternary Al x Ga 1-x As compound, wherein 0.8 ⁇ x ⁇ 1.
  • the diffusion barrier dielectric may be a thin film layer including a binary compound semiconductor GaAs, and the thin film layer may have a thickness of 150 to 1000 nm.
  • the thin film layer including a binary compound semiconductor GaAs may have a thermal expansion coefficient of 6 ⁇ 10 -6 /K at a temperature of 300 to 1000K with a variation of 2% or lower.
  • the support film may include a polymer layer and a support layer formed on the polymer layer, wherein the polymer layer may be formed of a polydimethylglutarimide material and the support layer may be formed of rubber or bisazide with a thickness of 1 to 10 ⁇ m.
  • the substrate may include a binary compound semiconductor GaAs
  • the separation of the solar cell structure and the support film from the substrate may be carried out by epitaxial lift-off (ELO), and the substrate may be reutilized after the separation.
  • ELO epitaxial lift-off
  • the present disclosure provides a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor including: a diffusion barrier dielectric including a thin film layer formed of binary compound semiconductor GaAs and having a thickness of 150 to 1000 nm; a molybdenum layer for a lower electrode, deposited on the diffusion barrier; a CIGS (Cu(In,Ga,Al)(Se,S) absorption layer deposited on the molybdenum layer and having a band gap of 1.04 to 3.49 eV; a CdS buffer layer deposited on the CIGS absorption layer; an undoped ZnO window layer deposited on the CdS buffer layer; a n-doped ZnO window layer deposited on the ZnO window layer; an anti-reflective layer deposited on the n-doped ZnO window layer; and a nickel and aluminum layer for an upper electrode, deposited on the anti-reflective layer.
  • a diffusion barrier dielectric including a thin film layer formed of
  • the thin film of GaAs diffusion barrier dielectric prevents diffusion of impurities since it has an optimized thermal expansion coefficient with reference to the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer and the lower electrode molybdenum layer, and inhibits lower electrode cracking and CIGS layer separation caused by the difference of heat expansion coefficient of the CIGS layer, thereby improving the efficiency of the solar cell.
  • the method disclosed herein uses heterogeneous integration technology and epitaxial lift off (ELO) that enables recycle of a substrate, and thus it is possible to provide a high-efficiency flexible thin film solar cell having improved cost efficiency and flexibility.
  • Figs. 1 to 5 are schematic sectional views illustrating the method for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
  • Fig. 6 is a sectional view showing the structure of a thin film solar cell used for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
  • substrate 110 sacrificial layer
  • Figs. 1 to 5 are schematic sectional views illustrating the method for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
  • a substrate 100 may include various types of compound semiconductor materials, particularly GaAs, favorable to scale-up and cost efficient work.
  • a sacrificial layer 110 is formed on the substrate 100.
  • the sacrificial layer 110 may include a ternary aluminum (Al)-containing compound.
  • the sacrificial layer 110 may include Al x Ga 1-x As(0.8 ⁇ x ⁇ 1).
  • hydrofluoric acid (HF) solution diluted with deionized (DI) water is effective for etching Al selectively. Therefore, for the purpose of selective etching of the sacrificial layer 110, a material having a high Al content may be used to form the sacrificial layer 110 so as to allow selective etching.
  • a diffusion barrier dielectric 210 is formed on the sacrificial layer 110.
  • the diffusion barrier dielectric is a thin film layer formed of binary compound semiconductor GaAs.
  • the thin film layer including binary compound semiconductor GaAs has a thermal expansion coefficient of 6 ⁇ 10 -6 /K (5.88 to 6.12 ⁇ 10 -6 /K) at a temperature of 300 to 1000K with a variation of 2% or lower. In other words, such a thermal expansion coefficient is as low as 6 ⁇ 10 -6 /K with little variation.
  • the diffusion barrier dielectric 210 has a very low heat expansion coefficient during a high-temperature process at 600 °C or higher, which is an optimized condition with reference to a molybdenum layer 221 for a lower electrode and a CIGS absorption layer 222. Therefore, it is possible to prevent separation of the CIGS absorption layer caused by the difference between the thermal expansion coefficients of the different layers.
  • the GaAs thin film, i.e., the diffusion barrier dielectric 210 may serve not only as a barrier layer capable of preventing diffusion of impurities but also as a dielectric.
  • the GaAs thin film as a diffusion barrier dielectric 210 serves to prevent the thin film solar cell from deformation caused by undesired etching from HF solution during the separation of the thin film.
  • the diffusion barrier dielectric has a thickness of 150 to 1000 nm in order to improve cost efficiency.
  • a solar cell structure may be formed on the diffusion barrier dielectric 210.
  • Fig. 6 is a sectional view showing the structure of a thin film solar cell used for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
  • the thin film type solar cell structure 200 is shown in Fig. 6. More particularly, a molybdenum layer 221 for a lower electrode is formed on the GaAs thin film diffusion barrier dielectric 210, and a CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer 222, a CdS buffer layer 223, an undoped ZnO window layer 224, a n-doped ZnO window layer 225, an anti-reflective layer 226 and a nickel and aluminum layer 227 for an upper electrode are stacked successively on the molybdenum layer 221 for a lower electrode.
  • CIGS Cu(In,Ga,Al)(Se,S)
  • the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer has a band gap of 1.04 to 3.49 eV.
  • a support film 300 may be further formed on the solar cell structure 200, the support film being intended to support the solar cell structure 200 and to prevent the solar cell structure 200 from being damaged by the deformation that may occur during the separation of the thin film.
  • the support film 300 may include a polymer layer 310 and a support layer 320 formed on the polymer layer 310.
  • the polymer layer 310 may include a tackifying material, such as polydimethylglutarimide that is adhered easily to the surface of the solar cell structure 200.
  • the support layer 320 may include any one selected from rubber and bisazide having a thickness of 1 to 10 ⁇ m so as to support or hold the separated solar cell structure 200.
  • the sacrificial layer 110 is subjected to etching so that the solar cell structure 200 is separated from the substrate 100.
  • a HF solution diluted with DI water to a concentration of 12.5 wt% is used to perform selective etching of the sacrificial layer 110 so that the solar cell structure 200 may be separated.
  • the sacrificial layer 110 is etched preferably with HF solution diluted with DI water, the scope of the present disclosure is not limited thereto. Any solution capable of selective etching of the sacrificial layer 110 may be used to perform etching of the sacrificial layer 110.
  • the substrate 100 may be reutilized to fabricate another solar cell structure 200.
  • the substrate includes a binary compound semiconductor GaAs, and the separation of the solar cell structure and the support film from the substrate is carried out via epitaxial lift-off (ELO). After the separation, the substrate may be recycled.
  • ELO epitaxial lift-off
  • the solar cell structure 200 may be dipped into DI water to remove the sacrificial layer materials remaining on the solar cell structure 200 and to wash the solar cell structure 200.
  • Dipping of the solar cell structure 200 in DI water removes a part of the sacrificial layer materials remaining on the surface of the solar cell structure 200, and washes the surface of the solar cell structure 200.
  • the solar cell structure 200 is integrated with an optional heterogeneous flexible host substrate 500.
  • the surface of the solar cell structure 200 is coated with DI water and the surface of the heterogeneous flexible host substrate 500 may be hydrophilized through plasma treatment.
  • the solar cell structure 200 may be integrated with the host substrate 500 by way of Van der Waals force.
  • the host substrate 500 includes a material different from that of the substrate 100 used for forming the solar cell structure 200.
  • the host substrate may include silicone, ceramics, plastics or other flexible materials. Although some materials are exemplified herein as the material for the host substrate 500, the scope of the present disclosure is not limited thereto. Any materials different from the material forming the substrate 100 may be used.
  • the solar cell obtained by the method for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure includes the solar cell structure 200 disposed on the optional flexible host substrate 500.
  • Fig. 6 is a sectional view showing the structure of a thin film solar cell used for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
  • the flexible thin film solar cell structure using a chalcopyrite-based compound semiconductor includes: a diffusion barrier dielectric including a thin film formed of binary compound semiconductor GaAs and having a thickness of 150 to 1000 nm; a molybdenum layer for a lower electrode, deposited on the diffusion barrier; a CIGS (Cu(In,Ga,Al)(Se,S) absorption layer deposited on the molybdenum layer and having a band gap of 1.04 to 3.49 eV; a CdS buffer layer deposited on the CIGS absorption layer; an undoped ZnO window layer deposited on the CdS buffer layer; a n-doped ZnO window layer deposited on the ZnO window layer; an anti-reflective layer deposited on the n-doped ZnO window layer; and a nickel and aluminum layer for an upper electrode, deposited on the anti-reflective layer.
  • a diffusion barrier dielectric including a thin film formed of binary compound semiconductor GaAs and having
  • the present application contains subject matter related to Korean PatentApplication No.10-2010-0094942, filed in the Korean Intellectual Property Office on 09.30.2010., the entire contents of which is incorporated herein by reference.

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Abstract

Provided is a method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor, including: forming a sacrificial layer on a substrate; forming a solar cell structure including a diffusion barrier dielectric on the top of the sacrificial layer; forming a support film on the top of the solar cell structure; carrying out selective etching of the sacrificial layer to separate the solar cell structure and the support film from the substrate; and integrating the solar cell structure with a heterogeneous flexible host substrate and removing the support film. In the high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor according to the present disclosure, the thin film of GaAs diffusion barrier dielectric prevents diffusion of impurities since it has an optimized thermal expansion coefficient with reference to the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer and the lower electrode molybdenum layer, and inhibits lower electrode cracking and CIGS layer separation caused by the difference of thermal expansion coefficient of the CIGS layer, thereby improving the efficiency of the solar cell. In addition, the method uses heterogeneous integration technology and epitaxial lift off (ELO) that enables recycle of a substrate, and thus it is possible to provide a high-efficiency flexible thin film solar cell having improved cost efficiency and flexibility.

Description

METHOD FOR FABRICATING HIGH EFFICIENCY FLEXIBLE COMPOUND SEMICONDUCTOR THIN FILM SOLAR CELL WITH CHALCOPYRITE SYSTEM
The present disclosure relates to a method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor, and more particularly, to a method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor, which utilizes heterogeneous integration technology and includes, as a diffusion barrier and a dielectric, a binary compound semiconductor GaAs thin film having excellent thermal expansion coefficient selectivity.
Group I-III-VI2 chalcopyrite-based compound semiconductors, such as CIGS(Cu(In,Ga,Al)(Se,S)), have a direct transition type energy band gap and the highest light absorption coefficient, 1×105cm-1, among known semiconductors. Therefore, such compound semiconductors enable fabrication of a high-efficiency solar cell even when used as a thin film with a thickness of 1 to 2 micrometers. In addition, they have excellent long-term electro-optical stability and radiation hardness, so that they may be useful for universal solar cell applications as well as ground power supply applications.
One of the possible applications of the compound semiconductor solar cell, i.e., building integrated photovoltaics(BIPV) requires a high-efficiency flexible CIGS thin film solar cell. As a result, many studies have been conducted about high-efficiency CIGS thin film solar cells, etc., using flexible materials, for example, a flexible metal sheet, such as titanium or molybdenum, cheap stainless steel foil or polyimide.
However, flexible metal sheets, such as titanium or molybdenum, may contribute to improvement of efficiency but be not cost-efficient. In the case of cheap stainless steel foil, there is a problem of diffusion of substrate ingredients, such as Fe, Ni or Cr, during heat treatment at high temperature, resulting in degradation of the efficiency of a CIGS thin film solar cell. Thus, there is an additional need for a diffusion barrier capable of inhibiting diffusion of such impurities. In addition, polyimide as a polymeric material has poor thermal stability and a high thermal expansion coefficient, and thus is limited in its application to a high-temperature process required for a high-efficiency solar cell.
CIGS thin film solar cell modules fabricated based on low carbon steel forming a diffusion barrier via an expensive vacuum deposition process have an efficiency of about 16%, which is the highest efficiency level as compared to other CIGS thin film solar cells using a flexible substrate. Recently, it is possible to form a diffusion barrier under atmospheric pressure, and thus to fabricate flexible CIGS thin film solar cells having improved efficiency in combination with high cost-efficiency.
However, the aforementioned thin film solar cells still have problems in that they frequently cause separation of CIGS films, including cracking of a lower electrode, and they have an insufficient efficiency as compared to the efficiency (20.7%) of CIGS thin film solar cells fabricated on a soda lime glass substrate.
Therefore, there is an imminent need for providing a method for fabricating a flexible CIGS thin film solar cell that shows an optimized combination of the requirement of the heat expansion coefficient, which is a main cause of the separation of a CIGS film, with the applicability not only as a thin film solar cell using a solid substrate capable of preventing diffusion of impurities but also as a flexible thin film solar cell.
The present disclosure is directed to providing a method for fabricating a high-efficiency flexible thin film solar cell using a CIGS-based compound semiconductor, which realizes improved efficiency of CIGS thin film solar cell, prevents separation of a CIGS film and cracking of a lower electrode, and shows improved process efficiency.
The present disclosure is also directed to providing a high-efficiency flexible thin film solar cell using a CIGS-based compound semiconductor, which prevents separation of a CIGS film and cracking of a lower electrode.
In one general aspect, the present disclosure provides a method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor includes: forming a sacrificial layer on a substrate; forming a solar cell structure including a diffusion barrier dielectric on the top of the sacrificial layer; forming a support film on the top of the solar cell structure; carrying out selective etching of the sacrificial layer to separate the solar cell structure and the support film from the substrate; and integrating the solar cell structure with a heterogeneous flexible host substrate and removing the support film.
According to an embodiment, the solar cell structure may include a molybdenum layer for a lower electrode, a CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer, a CdS buffer layer, an undoped ZnO window layer, a n-doped ZnO window layer, an anti-reflective layer, and a nickel and aluminum layer for an upper electrode, stacked successively on the diffusion barrier dielectric.
According to another embodiment, the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer may have a band gap of 1.04 to 3.49 eV.
According to still another embodiment, the sacrificial layer may include an aluminum-containing ternary AlxGa1-xAs compound, wherein 0.8≤x<1.
According to still another embodiment, the diffusion barrier dielectric may be a thin film layer including a binary compound semiconductor GaAs, and the thin film layer may have a thickness of 150 to 1000 nm.
According to still another embodiment, the thin film layer including a binary compound semiconductor GaAs may have a thermal expansion coefficient of 6×10-6/K at a temperature of 300 to 1000K with a variation of 2% or lower.
According to still another embodiment, the support film may include a polymer layer and a support layer formed on the polymer layer, wherein the polymer layer may be formed of a polydimethylglutarimide material and the support layer may be formed of rubber or bisazide with a thickness of 1 to 10 ㎛.
According to yet another embodiment, the substrate may include a binary compound semiconductor GaAs, the separation of the solar cell structure and the support film from the substrate may be carried out by epitaxial lift-off (ELO), and the substrate may be reutilized after the separation.
In another general aspect, the present disclosure provides a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor including: a diffusion barrier dielectric including a thin film layer formed of binary compound semiconductor GaAs and having a thickness of 150 to 1000 nm; a molybdenum layer for a lower electrode, deposited on the diffusion barrier; a CIGS (Cu(In,Ga,Al)(Se,S) absorption layer deposited on the molybdenum layer and having a band gap of 1.04 to 3.49 eV; a CdS buffer layer deposited on the CIGS absorption layer; an undoped ZnO window layer deposited on the CdS buffer layer; a n-doped ZnO window layer deposited on the ZnO window layer; an anti-reflective layer deposited on the n-doped ZnO window layer; and a nickel and aluminum layer for an upper electrode, deposited on the anti-reflective layer.
According to the high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor disclosed herein, the thin film of GaAs diffusion barrier dielectric prevents diffusion of impurities since it has an optimized thermal expansion coefficient with reference to the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer and the lower electrode molybdenum layer, and inhibits lower electrode cracking and CIGS layer separation caused by the difference of heat expansion coefficient of the CIGS layer, thereby improving the efficiency of the solar cell. In addition, the method disclosed herein uses heterogeneous integration technology and epitaxial lift off (ELO) that enables recycle of a substrate, and thus it is possible to provide a high-efficiency flexible thin film solar cell having improved cost efficiency and flexibility.
The above and other objects, features and advantages of the present disclosure will become apparent from the following description of certain exemplary embodiments given in conjunction with the accompanying drawings, in which:
Figs. 1 to 5 are schematic sectional views illustrating the method for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure; and
Fig. 6 is a sectional view showing the structure of a thin film solar cell used for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
[Detailed Description of Main Elements]
100: substrate 110: sacrificial layer
200: solar cell structure
210: diffusion barrier dielectric
220: CIGS thin film solar cell
221: molybdenum layer for lower electrode
222: CIGS absorption layer
223: CdS buffer layer
224: undoped ZnO window layer
225: n-type ZnO window layer
226: anti-reflective layer
227: nickel and aluminum layer for upper electrode
300: support film 310: polymer layer
320: support layer 500: host substrate
Hereinafter, the embodiments of the present disclosure will be described in detail with reference to accompanying drawings. In the drawings, like reference numerals in the drawings denote like elements. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments.
Figs. 1 to 5 are schematic sectional views illustrating the method for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
First, as shown in Fig. 1, a substrate 100 may include various types of compound semiconductor materials, particularly GaAs, favorable to scale-up and cost efficient work.
A sacrificial layer 110 is formed on the substrate 100. The sacrificial layer 110 may include a ternary aluminum (Al)-containing compound. Preferably, the sacrificial layer 110 may include AlxGa1-xAs(0.8≤x<1). In the subsequent operation of etching the sacrificial layer, hydrofluoric acid (HF) solution diluted with deionized (DI) water is effective for etching Al selectively. Therefore, for the purpose of selective etching of the sacrificial layer 110, a material having a high Al content may be used to form the sacrificial layer 110 so as to allow selective etching.
After forming the sacrificial layer 110, a diffusion barrier dielectric 210 is formed on the sacrificial layer 110. The diffusion barrier dielectric is a thin film layer formed of binary compound semiconductor GaAs. Herein, the thin film layer including binary compound semiconductor GaAs has a thermal expansion coefficient of 6×10-6/K (5.88 to 6.12×10-6/K) at a temperature of 300 to 1000K with a variation of 2% or lower. In other words, such a thermal expansion coefficient is as low as 6×10-6/K with little variation.
The diffusion barrier dielectric 210 has a very low heat expansion coefficient during a high-temperature process at 600 ℃ or higher, which is an optimized condition with reference to a molybdenum layer 221 for a lower electrode and a CIGS absorption layer 222. Therefore, it is possible to prevent separation of the CIGS absorption layer caused by the difference between the thermal expansion coefficients of the different layers. The GaAs thin film, i.e., the diffusion barrier dielectric 210 may serve not only as a barrier layer capable of preventing diffusion of impurities but also as a dielectric.
In addition, the GaAs thin film as a diffusion barrier dielectric 210 serves to prevent the thin film solar cell from deformation caused by undesired etching from HF solution during the separation of the thin film. The diffusion barrier dielectric has a thickness of 150 to 1000 nm in order to improve cost efficiency.
Then, a solar cell structure may be formed on the diffusion barrier dielectric 210. Fig. 6 is a sectional view showing the structure of a thin film solar cell used for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
The thin film type solar cell structure 200 is shown in Fig. 6. More particularly, a molybdenum layer 221 for a lower electrode is formed on the GaAs thin film diffusion barrier dielectric 210, and a CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer 222, a CdS buffer layer 223, an undoped ZnO window layer 224, a n-doped ZnO window layer 225, an anti-reflective layer 226 and a nickel and aluminum layer 227 for an upper electrode are stacked successively on the molybdenum layer 221 for a lower electrode.
The CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer has a band gap of 1.04 to 3.49 eV.
After forming the solar cell structure 200, as shown in Fig. 2, a support film 300 may be further formed on the solar cell structure 200, the support film being intended to support the solar cell structure 200 and to prevent the solar cell structure 200 from being damaged by the deformation that may occur during the separation of the thin film.
The support film 300 may include a polymer layer 310 and a support layer 320 formed on the polymer layer 310.
The polymer layer 310 may include a tackifying material, such as polydimethylglutarimide that is adhered easily to the surface of the solar cell structure 200. In addition, the support layer 320 may include any one selected from rubber and bisazide having a thickness of 1 to 10 ㎛ so as to support or hold the separated solar cell structure 200.
After forming the support film 300 on the solar cell structure 200, as shown in Fig. 3, the sacrificial layer 110 is subjected to etching so that the solar cell structure 200 is separated from the substrate 100.
More particularly, a HF solution diluted with DI water to a concentration of 12.5 wt% is used to perform selective etching of the sacrificial layer 110 so that the solar cell structure 200 may be separated.
Although it is describe herein that the sacrificial layer 110 is etched preferably with HF solution diluted with DI water, the scope of the present disclosure is not limited thereto. Any solution capable of selective etching of the sacrificial layer 110 may be used to perform etching of the sacrificial layer 110.
Once the solar cell structure 200 is separated off, the substrate 100 may be reutilized to fabricate another solar cell structure 200.
The substrate includes a binary compound semiconductor GaAs, and the separation of the solar cell structure and the support film from the substrate is carried out via epitaxial lift-off (ELO). After the separation, the substrate may be recycled.
After separating the solar cell structure 200, the solar cell structure 200 may be dipped into DI water to remove the sacrificial layer materials remaining on the solar cell structure 200 and to wash the solar cell structure 200.
Dipping of the solar cell structure 200 in DI water removes a part of the sacrificial layer materials remaining on the surface of the solar cell structure 200, and washes the surface of the solar cell structure 200.
After separating the solar cell structure 200, as shown in Fig. 4, the solar cell structure 200 is integrated with an optional heterogeneous flexible host substrate 500.
Herein, the surface of the solar cell structure 200 is coated with DI water and the surface of the heterogeneous flexible host substrate 500 may be hydrophilized through plasma treatment. In this manner, the solar cell structure 200 may be integrated with the host substrate 500 by way of Van der Waals force.
Finally, after the solar cell structure 200 is integrated with the optional heterogeneous flexible host substrate 500, as shown in Fig. 5, DI water remaining on the circumference of the solar cell structure 200 is allowed to evaporate, and the support film 300 including the polymer layer and the support layer is removed to provide a compound semiconductor solar cell integrated with the heterogeneous flexible host substrate 500.
The host substrate 500 includes a material different from that of the substrate 100 used for forming the solar cell structure 200. For example, the host substrate may include silicone, ceramics, plastics or other flexible materials. Although some materials are exemplified herein as the material for the host substrate 500, the scope of the present disclosure is not limited thereto. Any materials different from the material forming the substrate 100 may be used.
Referring to Figs. 1 to 6, the solar cell obtained by the method for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure includes the solar cell structure 200 disposed on the optional flexible host substrate 500.
Fig. 6 is a sectional view showing the structure of a thin film solar cell used for fabricating a flexible thin film solar cell using a CIGS compound semiconductor according to an embodiment of the present disclosure.
As shown in Fig. 6, the flexible thin film solar cell structure using a chalcopyrite-based compound semiconductor includes: a diffusion barrier dielectric including a thin film formed of binary compound semiconductor GaAs and having a thickness of 150 to 1000 nm; a molybdenum layer for a lower electrode, deposited on the diffusion barrier; a CIGS (Cu(In,Ga,Al)(Se,S) absorption layer deposited on the molybdenum layer and having a band gap of 1.04 to 3.49 eV; a CdS buffer layer deposited on the CIGS absorption layer; an undoped ZnO window layer deposited on the CdS buffer layer; a n-doped ZnO window layer deposited on the ZnO window layer; an anti-reflective layer deposited on the n-doped ZnO window layer; and a nickel and aluminum layer for an upper electrode, deposited on the anti-reflective layer.
The present application contains subject matter related to Korean PatentApplication No.10-2010-0094942, filed in the Korean Intellectual Property Office on 09.30.2010., the entire contents of which is incorporated herein by reference.
Those skilled in the art will appreciate that the conceptions and specific embodiments of the high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor and the method for fabricating the same disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present disclosure. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the disclosure as set forth in the appended claims.

Claims (8)

  1. A method for fabricating a high-efficiency flexible thin film solar cell using a chalcopyrite-based compound semiconductor, comprising:
    forming a sacrificial layer on a substrate and forming a solar cell structure comprising a diffusion barrier dielectric on the top of the sacrificial layer;
    forming a support film on the top of the solar cell structure;
    carrying out selective etching of the sacrificial layer to separate the solar cell structure and the support film from the substrate; and
    integrating the solar cell structure with a heterogeneous flexible host substrate and removing the support film.
  2. The method according to claim 1, wherein the solar cell structure comprises a molybdenum layer for a lower electrode, a CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer, a CdS buffer layer, an undoped ZnO window layer, a n-doped ZnO window layer, anti-reflective layer, and a nickel and aluminum layer for an upper electrode, stacked successively on the diffusion barrier dielectric.
  3. The method according to claim 2, wherein the CIGS (Cu(In,Ga,Al)(Se,S)) absorption layer has a band gap of 1.04 to 3.49 eV.
  4. The method according to claim 1, wherein the sacrificial layer comprises an aluminum-containing ternary AlxGa1-xAs compound,wherein 0.8≤x<1.
  5. The method according to claim 1, wherein the diffusion barrier dielectric is a thin film layer comprising binary compound semiconductor GaAs, and the thin film layer has a thickness of 150 to 1000 nm.
  6. The method according to claim 5, wherein the thin film layer comprising binary compound semiconductor GaAs has a thermal expansion coefficient of 5.88×10-6/K to 6.12×10-6/K at a temperature of 300 to 1000K.
  7. The method according to claim 1, wherein the support film comprises a polymer layer and a support layer formed on the polymer layer, wherein the polymer layer is formed of a polydimethylglutarimide material and the support layer is formed of rubber or bisazide with a thickness of 1 to 10 ㎛.
  8. A high-efficiency flexible thin film solar cell having a chalcopyrite-based compound semiconductor, comprising:
    a diffusion barrier dielectric comprising a thin film formed of binary compound semiconductor GaAs and having a thickness of 150 to 1000 nm;
    a molybdenum layer for a lower electrode, deposited on the diffusion barrier;
    a CIGS (Cu(In,Ga,Al)(Se,S) absorption layer deposited on the molybdenum layer and having a band gap of 1.04 to 3.49 eV;
    a CdS buffer layer deposited on the CIGS absorption layer;
    an undoped ZnO window layer deposited on the CdS buffer layer;
    a n-doped ZnO window layer deposited on the ZnO window layer;
    an anti-reflective layer deposited on the n-doped ZnO window layer; and
    a nickel and aluminum layer for an upper electrode, deposited on the anti-reflective layer.
PCT/KR2010/008479 2010-09-30 2010-11-29 Method for fabricating high efficiency flexible compound semiconductor thin film solar cell with chalcopyrite system WO2012043929A1 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013162498A1 (en) * 2012-04-23 2013-10-31 Empire Technology Development Llc Lift-off layer for separation and disposal of energy conversion devices
EP3095137A2 (en) * 2014-01-15 2016-11-23 The Regents Of The University Of Michigan Integration of epitaxial lift-off solar cells with mini-parabolic concentrator arrays via printing method
WO2017040547A3 (en) * 2015-08-31 2017-04-27 Stc.Unm Mixed group-v sacrificial layers for release and transfer of membranes
CN110071193A (en) * 2019-05-13 2019-07-30 中国科学院电工研究所 A kind of binode stacked solar cell, cascade solar cell and preparation method thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6312996B2 (en) * 2012-09-26 2018-04-18 株式会社東芝 Photoelectric conversion element and solar cell
KR101440716B1 (en) 2013-01-10 2014-09-18 경희대학교 산학협력단 Manufacturing Method of Flexible CIGS/CIS Inorganic Thin Film Solar Cell and Solar Cell Using The Same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090114274A1 (en) * 2007-11-02 2009-05-07 Fritzemeier Leslie G Crystalline thin-film photovoltaic structures
KR20100047246A (en) * 2007-07-03 2010-05-07 마이크로링크 디바이시즈, 인크. Methods for fabricating thin film iii-v compound solar cell
KR20100090181A (en) * 2009-02-05 2010-08-13 (주)포인트엔지니어링 Manufacturing of thin film solar cell by porous materials and solar cell

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100961518B1 (en) 2009-07-24 2010-06-07 동국대학교 산학협력단 Apparatus and method for substrate manufacturing of flexible solar cell and manufacturing method of solar cell using the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20100047246A (en) * 2007-07-03 2010-05-07 마이크로링크 디바이시즈, 인크. Methods for fabricating thin film iii-v compound solar cell
US20090114274A1 (en) * 2007-11-02 2009-05-07 Fritzemeier Leslie G Crystalline thin-film photovoltaic structures
KR20100090181A (en) * 2009-02-05 2010-08-13 (주)포인트엔지니어링 Manufacturing of thin film solar cell by porous materials and solar cell

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013162498A1 (en) * 2012-04-23 2013-10-31 Empire Technology Development Llc Lift-off layer for separation and disposal of energy conversion devices
US9331221B2 (en) 2012-04-23 2016-05-03 Empire Technology Development Llc Lift-off layer for separation and disposal of energy conversion devices
EP3095137A2 (en) * 2014-01-15 2016-11-23 The Regents Of The University Of Michigan Integration of epitaxial lift-off solar cells with mini-parabolic concentrator arrays via printing method
WO2017040547A3 (en) * 2015-08-31 2017-04-27 Stc.Unm Mixed group-v sacrificial layers for release and transfer of membranes
CN110071193A (en) * 2019-05-13 2019-07-30 中国科学院电工研究所 A kind of binode stacked solar cell, cascade solar cell and preparation method thereof

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