WO2011075561A1 - Chimies de plaquage d'absorbeurs pour cellules solaires en couche mince des groupes ib/iiia/via - Google Patents

Chimies de plaquage d'absorbeurs pour cellules solaires en couche mince des groupes ib/iiia/via Download PDF

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WO2011075561A1
WO2011075561A1 PCT/US2010/060704 US2010060704W WO2011075561A1 WO 2011075561 A1 WO2011075561 A1 WO 2011075561A1 US 2010060704 W US2010060704 W US 2010060704W WO 2011075561 A1 WO2011075561 A1 WO 2011075561A1
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film
layer
electrodeposition
alloy
copper
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PCT/US2010/060704
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WO2011075561A8 (fr
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Serdar Aksu
Jiaxiong Wang
Mustafa Pinarbasi
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Solopower, Inc.
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Priority claimed from US12/642,691 external-priority patent/US20100140098A1/en
Priority claimed from US12/642,702 external-priority patent/US8425753B2/en
Priority claimed from US12/642,709 external-priority patent/US8409418B2/en
Application filed by Solopower, Inc. filed Critical Solopower, Inc.
Priority to CN2010800573802A priority Critical patent/CN102859046A/zh
Publication of WO2011075561A1 publication Critical patent/WO2011075561A1/fr
Publication of WO2011075561A8 publication Critical patent/WO2011075561A8/fr

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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
    • H01L31/0256—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 the material
    • H01L31/0264—Inorganic materials
    • H01L31/032—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
    • H01L31/0322—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/10—Electroplating with more than one layer of the same or of different metals
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/60—Electroplating characterised by the structure or texture of the layers
    • C25D5/605—Surface topography of the layers, e.g. rough, dendritic or nodular layers
    • C25D5/611—Smooth layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/12—Semiconductors
    • C25D7/123—Semiconductors first coated with a seed layer or a conductive layer
    • C25D7/126—Semiconductors first coated with a seed layer or a conductive layer for solar cells
    • 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 invention relates to electroplating chemistries and methods for preparing semiconductor thin films for photovoltaic applications, specifically to plating electrolytes and methods for the processing Group IBIIIAVIA compound layers for thin film solar cells.
  • Solar cells are photovoltaic devices that convert sunlight directly into electrical power.
  • the most common solar cell material is silicon, which can be used in the form of single or polycrystalline wafers.
  • silicon-based solar cells the cost of electricity generated using silicon-based solar cells is higher than the cost of electricity generated by the more traditional methods. Therefore, since early 1970's there has been an effort to reduce cost of solar cells for terrestrial use.
  • One way of reducing the cost of solar cells is to develop low-cost thin film growth techniques that can deposit solar-cell- quality absorber materials on large area substrates and to fabricate these devices using high- throughput, low-cost methods.
  • Group IBIIIAVIA compound semiconductors comprising some of the Group IB such as (Cu), silver (Ag), gold (Au), Group IIIA such as boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl), and Group VIA such as oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po) materials or elements of the periodic table are excellent absorber materials for thin film solar cell structures.
  • Group IBIIIAVIA compound semiconductors comprising some of the Group IB such as (Cu), silver (Ag), gold (Au), Group IIIA such as boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl), and Group VIA such as oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po) materials or elements of the periodic table are excellent absorber materials for thin film solar cell structures.
  • compounds containing: i) Cu from Group IB, ii) at least one of In, Ga, and Al from Group IIIA, and iii) at least one of S, Se, and Te from Group VIA, are of great interest for solar cell applications.
  • Cu (In,Ga) (S,Se) 2 is the most advanced and solar cells in the 12-20% efficiency range have been demonstrated using this material as the absorber.
  • Aluminum containing chalcopyrites such as Cu(In,Al)Se 2 layers have also yielded over 12% efficient solar cells.
  • FIG. 1 The structure of a conventional Group IB IIIA VIA compound photovoltaic cell such as a Cu(In,Ga,Al)(S,Se,Te) 2 thin film solar cell is shown in Figure 1.
  • the device 10 is fabricated on a substrate 11, such as a sheet of glass, a sheet of metal, an insulating foil or web, or a conductive foil or web.
  • the absorber film 12, which includes a material in the family of Cu(In,Ga,Al)(S,Se,Te)2 is grown over a conductive layer 13 or contact layer, which is previously deposited on the substrate 11 and which acts as the electrical contact to the device.
  • the substrate 11 and the conductive layer 13 form a base 13A on which the absorber film 12 is formed.
  • Various conductive layers comprising molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), stainless steel and the like have been used in the solar cell structure of Figure 1. If the substrate itself is a properly selected conductive material, it is possible not to use the conductive layer 13, since the substrate 11 may then be used as the ohmic contact to the device.
  • a transparent layer 14 such as a cadmium sulfide (CdS), zinc oxide (ZnO) or CdS/ZnO stack is formed on the absorber film.
  • Radiation 15 enters the device through the transparent layer 14.
  • Metallic grids may also be deposited over the transparent layer 14 to reduce the effective series resistance of the device.
  • the preferred electrical type of the absorber film 12 is p-type, and the preferred electrical type of the transparent layer 14 is n-type. However, an n-type absorber and a p-type window layer can also be utilized.
  • the preferred device structure of Figure 1 is called a "substrate-type" structure.
  • “superstrate-type” structure can also be constructed by depositing a transparent conductive layer on a transparent superstrate such as glass or transparent polymeric foil, and then depositing the
  • the efficiency of the device is a function of the molar ratio of Cu/(In+Ga). Furthermore, some of the important parameters of the cell, such as its open circuit voltage, short circuit current and fill factor vary with the molar ratio of the IIIA elements, i.e. the Ga/(Ga+In) molar ratio. In general, for good device performance
  • Cu/(In+Ga) molar ratio is kept at around or below 1.0.
  • the optical bandgap of the absorber layer increases and therefore the open circuit voltage of the solar cell increases while the short circuit current typically may decrease. It is important for a thin film deposition process to have the capability of controlling both the molar ratio of IB/IIIA, and the molar ratios of the Group IIIA components in the composition. It should be noted that although the chemical formula is often written as Cu(In,Ga)(S,Se)?, a more accurate formula for the compound is Cu(In,Ga)(S,Se)k, where k value is 2, although it is typically close to 2 but may not be exactly 2.
  • Cu(In,Ga) means all compositions from Culn to CuGa.
  • Cu(In,Ga)(S,Se)2 means the whole family of compounds with Ga (Ga+In) molar ratio varying from 0 to 1, and Se/(Se+S) molar ratio varying from 0 to 1.
  • the electronic and optical properties of the Group IBIIIAVIA compound are also a function of the relative amounts of the Group VIA elements.
  • compound properties such as resistivity, optical bandgap, minority carrier lifetime, mobility etc., depend on the Se/(S+Se) ratio as well as the previously mentioned Cu/(In+Ga) and Ga (Ga+In) molar ratios. Consequently, solar-to- electricity conversion efficiency of a CIGS(S)-based solar cell depends on the distribution profiles of Cu, In, Ga, Se and S through the thickness of the CIGS(S) absorber.
  • Evaporation is an expensive technique and non-uniformity problems over large surface areas preset difficulties.
  • the sputtering can be applies over large surface areas, it requires expensive systems and sputtering targets.
  • Electrodeposition offers a low-cost alternative for depositing CIGS precursor films in a high- volume manufacturing environment. Electrodeposition is a versatile deposition method with ability to yield thin films of metals, metal alloys and compounds which may be used in a wide variety of precursor layer structures. Electrodeposition equipment is low cost and the process is energy efficient since it is typically carried out at low temperatures. Materials utilization in electrodeposition processes can be close to 100% if stable electrolytes with long lifetime are employed. Electrodeposition is also suitable for high throughput roll to roll manufacturing.
  • CIS and CIGS precursors by electrodeposition are to form stacks consisted of individual elemental layers.
  • Precursor stacks such as Cu/In, Cu/In Se, Cu/In/Ga, and Cu/In/Ga/Se stacks can be electrodeposited on Mo coated substrates to form Mo/CIS and Mo/CIGS structures and subsequently annealed in inert or Se containing environments to manufacture CIS and CIGS absorber layers.
  • U.S. Patent 4,581,108 describes a low cost electrodeposition method to prepare a metallic precursor preparation. In this method a Cu In stack is first formed by electrodeposition on a substrateand the stack is heated in a reactive atmosphere containing Se to form a CIS absorber layer.
  • Fritz et al. used electrodeposition to form a Cu/In/Se stack on a substrate and a following rapid thermal annealing of the stack to form CIS [ Fritz et al., Thin Solid Films 247 (1994) 129].
  • a Cu In/Ga Se precursor stack is first electrodeposited andconverted to CIGS absorber by a subsequent rapid thermal processing step [Basol et al., Proc. 23rd European PVSEC, 2008, p. 2137].
  • One of the reasons for selecting Cu/In and Cu/In/Ga electrodeposition sequence is the fact that Cu, In and Ga can have very different standard plating potentials.
  • the standard electrode potentials of Cu/Cu 2+ , In/In 3+ and Ga Ga 3+ metal/ion couples in aqueous solutions are about +0.337 V, -0.342 V, and -0.52 V, respectively.
  • In deposition on the other hand, larger negative voltages are needed.
  • Ga deposition which is challenging due to hydrogen evolution, even larger negative voltages are required. Therefore, to form a stack including Cu, In and Ga, Cu was typically electroplated first. This was then followed by deposition of In and then Ga so that while plating the second metal over the first metal, the first metal does not dissolve into the electrolyte of the second metal. Therefore, prior-art methods have employed Cu/In/Ga stacks electroplated in that order, which limits the way in which Cu, In and Ga is distributed through the thickness of the precursor film.
  • One step electrodeposition of CIS or CIGS precursor films from a single electrolyte is another prior art approach for utilizing electrodeposition for CIGS cell fabrication as described in US Patent 7,297,868.
  • the precursor films plated from Cu-In-Ga-Se electroplating bath are subsequently subjected to a high temperature crystallization step to improve their photovoltaic properties.
  • an acidic electrolyte with a pH of approximately 2 was used.
  • the deposition bath used for the codeposition of Cu-In-Ga-Se by electrodeposition contained 0.02M Cu(NO 3 ) 2 .
  • a Cu-In-Ga electrolyte can be used to deposit only a ternary thin film layer of Cu-In-Ga as described by Ganchev et al., Thin Solid Films 511 - 512 (2006) 325 - 327.
  • This Cu-In-Ga bath contained 50-100 mg cuprous chloride (CuCl), 100-350 mg indium chloride (InCl 3 ), 1700 mg gallium nitrate (Ga(N0 3 ) 3 .7H 2 0) and 2M potassium thiocyanate (KSCN) as a complex agent in 0.2 liter of de-ionized water.
  • the present invention provides a method and precursor structure to form a Group IBIIIAIVA solar cell absorber layer.
  • a method of forming a Group IBIIIAVIA compound layer on a base comprising: forming a precursor layer on the base, comprising: electrodepositing a first film on the base using a first electrodeposition solution, the first film comprising a copper- indium-gallium ternary alloy; electrodepositing a second film on the metallic film using a second electrodeposition solution, the second film comprising one of a copper-selenium alloy, an indium-selenium alloy and a gallium-selenium alloy; and electroplating a third film comprising selenium on the second film; and reacting the precursor layer with selenium thereby forming the Group IBIIIAVIA compound layer on the base.
  • a precursor structure for forming a Group IBIIIAIVA solar cell absorber on a surface of a base comprising: a first alloy film formed on the surface of the base, the first alloy film comprising copper, indium and gallium, wherein the thickness of the first alloy film is at least 50 nm; a second alloy film comprising copper and selenium formed on the first alloy film; and a selenium film formed on the second alloy film.
  • Figure 1 is a cross-sectional view of a solar cell employing a Group IBIIIAVIA absorber layer
  • Figures 2 is a schematic view of an alloy film electrodeposited from an electrodeposition solution of the present invention.
  • Figure 3 is a schematic view of another alloy film electrodeposited from an
  • Figure 4A is a schematic view of a structure including a metallic layer and a
  • Figure 4B is a schematic view of a precursor structure including the structure shown in Figure 4A.
  • Figure 5 is a schematic view of an absorber of the present invention formed on a base.
  • the present invention provides electrodeposition methods and electrodeposition solution used to deposit precursor layers for forming group IBIIIAIVA absorber layers such as Cu(In,Ga)Se 2 or CIGS layer to manufacture photovoltaic cells or solar cells.
  • group IBIIIAIVA absorber layers such as Cu(In,Ga)Se 2 or CIGS layer to manufacture photovoltaic cells or solar cells.
  • a Group IB- IIIA electrodeposition solution of the present invention may be utilized to electrodeposit an alloy film comprising at least three ingredients, such as Cu, In and Ga, of a Cu(In,Ga)Se 2 layer onto substrates.
  • Figure 2 shows a metallic film 100 or alloy film electrodeposited from the
  • the metallic film 100 is a ternary Cu-In-Ga alloy film, which includes all the metallic components, i.e., Cu, In and Ga, of a CIGS precursor in a continuous matrix.
  • the electrodeposition process is carried out in a deposition station where the contact layer (cathode) and an anode are wetted by the electrodeposition solution. When electroplating potential applied between an anode and the contact layer 10, the metallic film is electrodeposited onto the contact layer. Principles of the electrodeposition process are well known and will not be repeated here for the sake of clarity.
  • the metallic film 100 When reacted with a Group VIA material, the metallic film 100 forms A CIGS absorber layer of a solar cell.
  • Cu, In and Ga elements may also be graded through the thickness of the Cu-ln-Ga ternary alloy film.
  • the contact layer 106 may be made of a molybdenum (Mo) layer deposited over the substrate 104 or a multiple layers of metals stacked on a Mo layer; for example, molybdenum and ruthenium multilayer (Mo/Ru), or molybdenum, ruthenium and copper multilayer (Mo/Ru/Cu).
  • the substrate 104 may be a flexible substrate, for example a stainless steel foil, or a aluminum foil, or a polymer.
  • the substrate may also be a rigid and transparent substrate such as glass.
  • the electrodeposition solution of the present invention is a copper indium gallium ternary alloy electrodeposition electrolyte and may comprise a solution prepared by dissolving Cu, In and Ga metals into their ionic forms as well as by dissolving soluble Cu, In and Ga salts, such as sulfates, chlorides, acetates, sulfamates, carbonates, nitrates, phosphates, oxides, perchlorates, and hydroxides and other salts of these elements in predetermined amounths.
  • Molar amounts of Cu, In and Ga ions in the electrodeposition solution might be adjusted according to preferred composition of the final desired precursor film.
  • the concentration range for dissolved Cu in the electrodeposition solution may be between 0.005 and 0.5 mol/liters, and preferably between 0.01 and 0.25 mol/liters.
  • the concentration range for dissolved Ga in the electrolyte may be 0.01 and 0.7 mol/liters, and preferably between 0.05 and 0.35 mol/liters.
  • the concentration range for dissolved In in the electrodeposition solution may be 0.01 and 0.7 mol/liters, and preferably between 0.05 and 0.35 mol/liters.
  • the electrodeposition solution of the present invention is formulated at the alkaline pH regime or high pH regime, where pH is greater than 9, or between 9 andl4, by incorporating complexing agents.
  • the electrodeposition solution can be prepared using at least one complexing agent selected from the group of organic complexing agents including amine and carboxylic groups. Common examples for these complexing agents may be citric acid, tartaric acid, ethylenediamine, triethanolamine, glycine, and ethylenediaminetetraacetic acid etc. If only one complexing agent is used, then an appropriate complexing agent that can form soluble complexes with both Cu, In and Ga should be selected.
  • each complexing agent can selectively complex each of the dissolved In Ga and Cu ions and bring plating potentials of these three metals to desired levels.
  • tartaric acid is a good complexing agent for indium in the alkaline pH regime because it provides tartrate ions which can form soluble indium tartrate species.
  • citric acid is a very suitable complexing agent for Ga in the alkaline pH regime since it provides citrate ions which can form soluble gallium citrate species. Both tartrate and citrate ions also complex copper ions in the alkaline pH regime.
  • ethylenediaminetetraacetic acid may also be included in the formulation. EDTA may form stronger soluble complexes with Cu ions compared to In and Ga ions.
  • electrodeposition potentials of Cu, Ga and In could be modified to allow electrodeposition of Cu-In-Ga ternary alloy metallic films.
  • tartaric acid may be substituted with alkali and alkali earth metal salts of tartaric acid, such as sodium tartrate, potassium tartrate, calcium tartrate, magnesium tartrate and the like. These optional chemicals may also be used as a source of tartrate ions in the electrodeposition solution of the present invention.
  • citric acid may be substituted with alkali and alkali earth metal salts of citric acid, such as sodium citrate, potassium citrate, calcium citrate, magnesium citrate or the like, which may also be used as a source of citrate ions in the electrodeposition solution of the present invention.
  • EDTA may also be substituted with alkali and alkali earth metal salts of EDTA such as disodium EDTA salt, dipotassium EDTA salt, EDTA calcium derivative disodium salt and EDTA magnesium derivative disodium salt, which may also be used as a source of
  • the electrodeposition solutions described in this invention operate at alkaline pH regime.
  • complexing agents included in the electrodeposition solution of the present invention are most active to form soluble metal complex species with Cu, Ga and In ions.
  • pH is less than 9
  • each of the such complexing agents are inactive due to the formation and predomination of protonated complex species.
  • the alkaline pH regime is the most suitable for the Cu-In-Ga electrodeopition solution of the present invention.
  • the complexing agents are almost fully deprotonated and form soluble metal-complex ions with Cu, Ga and In ions when the pH of the electrodeposition solution of the present invention is maintained at a value greater than 9.
  • the more preferable pH range in this invention is between 10 and 12.5.
  • electrodeposition potential or current density may be varied to distribute each of Cu, In and Ga according to predetermined profiles through the thickness of the first layer, as the Cu, In and Ga are electrodeposited from the electrodeposition solution of the present invention.
  • the molar rations of Cu, In and Ga in the deposited metallic films are changed or distributed within a predetermined distribution profile to provide preferred reaction kinetics when the metallic film is reacted with a Group VIA material, such as Se and/or S to form a CIGS absorber.
  • FIG. 3 shows a metallic film 200, which is a Cu-In-Ga ternary alloy metallic film, electrodeposited onto the base 102 from the electrodeposition solution of the present invention.
  • a first portion 200A or bottom portion of the metallic film 200 may be formed over the contact layer 106 with a composition that is high in Cu at the beginning of the electrodeposition process.
  • more In and Ga may be incorporated from the electrodepositon solution to form a second portion 200B or intermediate portion of the metallic film 200 on the first portion by adjusting the electrodeposition potential.
  • a third portion 200C or top portion of the metallic film 200 is formed on the second portion with a composition that is low in Cu.
  • This embodiment takes the advantage of the differences in the standard plating potentials of Cu, Ga and In.
  • Cu electrodeposition may be encouraged by applying low plating potentials or current densities as noted above to produce the first portion 200A. Therefore, at low plating potentials or current densities, the first portion 200A of the metallic film will be rich in Cu.
  • the third portion 200C of the metallic film 200 grows under high electrodeposition potential with a low Cu amount high in In and Ga. The metallic films, which are produced this way, would be very beneficial to regulate the desirable reaction pathways in formation of CIGS absorber layer.
  • a Group VIA material layer may be deposited onto the metallic film comprising Cu, In and Ga to form a precursor layer.
  • the Group VIA material is preferably selenium and may be electrodeposited over the metallic film from another electrodeposition solution.
  • the exclusion of Se in the Cu-Ga-In ternary electroplating solution of the present invention provides several advantages. First, it allows utilization of high deposition rates for Cu-In-Ga layers. In fact, a large range of deposition current densities from 1 mA/cm 2 to 60 inA/cm 2 can be used for the Cu-Ga-In ternary electroplating solution of the present invention. More preferable current density range of electrodeposition is between 10 to 40 60 mA/cm 2 . Second advantage is that the film composition, morphology and the electrical conductivity and defectivity can be much better controlled when Se is excluded. Electrodeposition of subsequent thin film layers with minimal defectivity is possible over a high quality Cu-In-Ga thin layer.
  • a third embodiment of the present invention provides a two step process including a first step to electrodeposit a copper, indium and gallium metallic film on the base and a second step to electrodeposit a supplementary film including a binary alloy having at least one of Cu-Se alloy, In- Se alloy and Ga-Se alloy on the metallic film.
  • the supplementary film is a Cu-Se film, it may induce formation of copper selenide at the very beginning of the subsequent reaction step to form the absorber.
  • the most of the Cu needed in the formation of a solar cell absorber may be included in the supplementary film deposited over the metallic film. For example a minimum 60% molar amount of all the copper needed for the final absorber may be in the supplementary film.
  • An additional step of the process may comprise depositing a Group VIA material such as substantially pure selenium over the supplementary film before reacting the precursors stack to form a CIGS absorber layer.
  • FIG. 4A shows a first film 300 formed over the base 102.
  • the first film 100 is a metallic film including a copper, indium and gallium ternary alloy (Cu-In-Ga alloy).
  • the molar amount of copper is less than 20% of the molar amount of copper in the final CIGS layer.
  • Cu and other molar amounts depend on the optimal values of Cu/(Ga+In) and Ga/(Ga+In) in the final CIGS absorbers.
  • the first film 300 is deposited over the contact layer 106 using, preferably, the electrodeposition solution described above.
  • the electrodeposition solution includes salts of Cu, In and Ga, one or more complexing agents and a high pH value.
  • Ratios of these elements may be reformulated with predetermined amounts to form the first layer 300.
  • a preferred electrodeposition current density may be in the range of 2.5 and 40 niA/cm 2 . This current density may be varied during the electrodeposition process so as to control the vertical distribution of Cu, in and Ga through the thickness of the first film 300 as described in the previous embodiment. By distributing Cu, In and Ga such way, it is possible to form a graded composition profile in the first film 300.
  • An exemplary first layer thickness may be in the range of 100-900 nm, and preferably 300-700 nm.
  • a second film 304 is deposited onto the first film 300 from, preferably, a second electrodeposition solution.
  • the second film 304 may be a binary alloy including one of copper- selenium (Cu-Se) alloy, indium-selenium (In-Se) alloy and gallium-selenium (Ga-Se) alloy.
  • the second film may be a Cu-Se alloy
  • the second electrodeposition solution includes a Cu salt, a Se source such as a selenious acid and organic acid additives which can solubilize Cu at a low pH regime.
  • a preferred pH range may be 0-3.
  • the second film 304 may be Cu rich and includes the most of the copper needed to form the final CIGS absorber layer.
  • a minimum 60% molar amount of all the copper needed for the final absorber may be in the second film 304.
  • Thickness of the second film is in the range of 50 to 800 nm.
  • a third film306, including a Group VIA material is deposited onto the second film 304 to complete a precursor layer or stack 310.
  • the Group VIA material is preferably selenium and electrodeposited over the second layer 304 from a third electrodeposition solution including selenium.
  • the precursor stack 310 can also be formed with the metallic films described in the previous embodiments.
  • a next stage of the process involves heat treatment and reaction needed to convert the precursor layer 310 into an absorber layer 312 or Group IBIIIAVIA compound layer.
  • the reaction step may involve heating the precursor film to a temperature range of 400-600 °C, optionally in the presence of Se provided by sources such as solid or liquid Se, 3 ⁇ 4Se gas, organometallic Se vapor sources, elemental Se vapors, and the like, for periods ranging from 1 minute to 30 minutes.
  • the heating rate from room temperature to the process or reaction temperature may be in the range of 1-50 °C/seconds, preferably in the range of 5-20 °C/seconds.
  • sulfur (S) and Na-doping compounds such as NaF may also be provided to the film during this reaction step.
  • the precursor film comprises excess amount of Se in addition to Cu, In and Ga
  • the annealing or the reaction step may be carried out in an inert atmosphere.
  • the Se vapor may be generated by heating solid or liquid Se sources or by applying organometallic Se sources among others.
  • the method is also applicable to roll-to-roll plating of the metallic films.
  • segmented anodes in the same plating bath could be used.
  • the applied voltage or the current at each anode segment could be controlled individually.
  • the composition of the alloy film deposited on the substrate roll (cathode) could be changed, while substrate is moving relative to the segmented anodes.
  • Example 1 Dependency of Cu-In-Ga alloy compositions upon current densities
  • the solution used in this example contained 0.1 M InCl 3 , 0.09 M GaCl 3 , 0.065 M CuS0 4 in 1.0 M potassium sodium tartrate with a pH value of 10.5.
  • Compositions of the resultant alloy films depend on the current densities applied in the plating. At a low current density, almost no Ga was plated into the films. At 5 niA/cm 2 for 80 seconds, for instance, the plated alloy film had a total thickness about 150 nm with a composition of 17 atomic percent In, and about 83% of Cu and negligible amount of Ga, which could be represented with a formula of Cu 5 In.
  • the plated film When the current density was increased to 20 mA/cm 2 , the plated film possesses a composition with a formula of Cu 3 ln 2 Ga with a thickness about 150 nm after a 20 second deposition period. Under a high current density such as 40 mA/cm 2 , the plated film gives rise to a formula of Cu 5 in 3 Ga 3 and a total thickness about 150 nm during a period of 10 seconds. In spite of different current densities, the same amount of total plating charge was applied in all of these three cases. They produce almost the same total thickness with various compositions. This suggests that the cathodic current efficiencies during the plating do not change much with incorporation of Ga into the films. The examinations of Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) indicated that all the films had an even and smooth surface morphology and uniformly distributed surface compositions.
  • SEM Scanning Electron Microscopy
  • EDS Energy Dispersive Spect
  • Example 2 Ga rich Cu-In-Ga alloy films
  • Ga Due to a very low reduction potential, Ga is more difficult to be plated into the Cu-In-Ga alloy films.
  • the Ga content can be increased with a high current density as described in Example 1, it is also possible to increase the concentration of Ga salt in the plating solution to incorporate more Ga into the film.
  • Example 3 Increasing In content in the Cu-In-Ga alloy films
  • the In content can be increased with a higher In concentration in the plating bath.
  • a plating bath containing 0.135 M InCl 3 , 0.06 M GaCl 3 , 0.07 M CuS0 4 in 1.0 M potassium sodium tartrate with a pH value of 10.5 was used.
  • the plating condition was 20 mA/cm 2 for 20 seconds.
  • the resultant alloy film has a formula of CuIno.71Gao.42 with a total thickness about 146 nm. Also the resultant film possesses a smooth surface and uniformly distributed surface composition.
  • the Cu-In-Ga alloy thin film deposited using the plating solution of the present invention can be used for the preparation of CIGS solar absorbers in several different ways.
  • the precursor can be deposited in one single plating step using this solution. This precursor can be annealed at high temperate in a reactive I3 ⁇ 4Se, H 2 S or Se environment to form the CIGS compound.
  • a Se layer can be deposited over the Cu-In-Ga layer and then the precursor is annealed at high temperature in either in an inert or a reactive H 2 Se, 3 ⁇ 4S or Se environment.
  • the Cu-In-Ga alloy film can also be used as one of the layers in an electrodeposited multilayer stack of elemental and alloy layers.

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Abstract

La présente invention porte sur un procédé et sur une structure de précurseur pour former une couche d'absorbeur pour cellule solaire des Groupes IBIIIAVIA. Le procédé consiste à former une couche composite des Groupes IBIIIAVIA sur une base par formation d'une couche de précurseur sur la base par électrodéposition de trois différents films, puis à faire réagir la couche de précurseur avec du sélénium pour former la couche composite des Groupes IBIIIAVIA sur la base. Les trois films, décrits par la couche de précurseur, comprennent dans un mode de réalisation un premier film d'alliage comprenant du cuivre, de l'indium et du gallium, un second film d'alliage comprenant du cuivre et du sélénium formé sur le premier film d'alliage ; et un film de sélénium sur le second film d'alliage.
PCT/US2010/060704 2009-12-18 2010-12-16 Chimies de plaquage d'absorbeurs pour cellules solaires en couche mince des groupes ib/iiia/via WO2011075561A1 (fr)

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US12/642,691 US20100140098A1 (en) 2008-05-15 2009-12-18 Selenium containing electrodeposition solution and methods
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US12/642,691 2009-12-18
US12/642,702 US8425753B2 (en) 2008-05-19 2009-12-18 Electroplating methods and chemistries for deposition of copper-indium-gallium containing thin films
US12/642,709 US8409418B2 (en) 2009-02-06 2009-12-18 Enhanced plating chemistries and methods for preparation of group IBIIIAVIA thin film solar cell absorbers

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PCT/US2010/060712 WO2011075564A1 (fr) 2009-12-18 2010-12-16 Procédés et chimies d'électroplaquage pour le dépôt de films minces à teneur en cuivre-indium-gallium

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RU2691408C2 (ru) * 2013-12-27 2019-06-13 Колгейт-Палмолив Компани Способы ухода за полостью рта с использованием сахарида в качестве пребиотика
RU2741492C2 (ru) * 2019-06-04 2021-01-26 Колгейт-Палмолив Компани Способы ухода за полостью рта с использованием сахарида в качестве пребиотика

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CN106935842B (zh) * 2017-03-08 2020-10-23 广东工业大学 电镀硒的镀液、锂硒电池正极材料及锂硒电池
CN114122388B (zh) * 2021-11-16 2024-04-02 信阳师范学院 一种用于钠离子电池的CuSe纳米材料及其制备方法

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US20070093006A1 (en) * 2005-10-24 2007-04-26 Basol Bulent M Technique For Preparing Precursor Films And Compound Layers For Thin Film Solar Cell Fabrication And Apparatus Corresponding Thereto
US20080057616A1 (en) * 2006-06-12 2008-03-06 Robinson Matthew R Bandgap grading in thin-film devices via solid group iiia particles
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US9410259B2 (en) 2011-09-02 2016-08-09 Alliance For Sustainable Energy, Llc Electrodeposition of gallium for photovoltaics
RU2691408C2 (ru) * 2013-12-27 2019-06-13 Колгейт-Палмолив Компани Способы ухода за полостью рта с использованием сахарида в качестве пребиотика
RU2741492C2 (ru) * 2019-06-04 2021-01-26 Колгейт-Палмолив Компани Способы ухода за полостью рта с использованием сахарида в качестве пребиотика

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