JP5536153B2 - Method of forming chalcogenide semiconductor film and photovoltaic device - Google Patents

Description

  The present invention relates to a photovoltaic device, and more particularly, to a method for forming a chalcogenide semiconductor film and a photovoltaic device using the chalcogenide semiconductor film.

  Photovoltaic devices are attracting attention due to the lack of energy on the earth. Photovoltaic devices are roughly classified into crystalline silicon solar cells and thin film solar cells. Crystalline silicon solar cells have become mainstream photovoltaic devices due to their mature manufacturing technology and high efficiency. However, crystalline silicon solar cells have never become common solar cells due to their high material costs and manufacturing costs. Thin film solar cells are manufactured by forming a light absorption layer on a non-silicon substrate such as a glass substrate. There is no shortage of glass substrates, and the price of glass substrates is cheaper compared to silicon wafers used in crystalline silicon solar cells. Hence, thin film solar cells are regarded as an alternative to crystalline silicon solar cells.

  Thin film solar cells are made of light absorbing layers such as amorphous silicon, polycrystalline silicon, cadmium telluride (CdTe), copper indium gallium selenide (CIS or CIGS), dye sensitized film (DSC) and other organic films. Can be further classified. Among these thin film solar cells, CIGS solar cells have reached 20% cell efficiency comparable to crystalline silicon solar cells.

The quaternary semiconductor Cu ₂ ZnSn (S, Se) ₄ (CZTS) having a crystal structure similar to CIGS has attracted attention in recent years because it is a low-cost, naturally abundant and non-toxic element. It is a new photovoltaic material. Ito and Nakamura reported that CZTS thin films were formed on stainless steel substrates by atomic beam sputtering. Friedel Meier et al. Formed a CZTS thin film by heat evaporation, and a CZTS solar cell formed by this method has a conversion efficiency of 2.3%. Katagiri et al. Formed a CZTS thin film by co-sputtering with an RF power source, followed by sulfidation of vapor phase sulfidation or electron beam evaporation precursors, and the efficiency of the resulting CZTS solar cell was 6.77. %.

  As mentioned above, conventional methods of forming CZTS solar cells typically use a vacuum process. However, processing in vacuum is generally quite expensive, thus increasing the cost of CZTS solar cells. Accordingly, a solution process that does not require a vacuum device is required to reduce manufacturing costs.

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Hironori Katagiri et al. , “Preparation and evaluation of Cu2ZnSnS4 thin films by sulfurating of E-B evolved precursors”, 1997, pages 407-414, Solar Energy Materials 49. Qijie Guo et al. "Synthesis of Cu2ZnSnS4 Nanocrystalline Ink and It's Use for Solar Cells", 2009/07/31, pages 11672-11673, VOL. 131, NO. 33, J.M. AM. CHEM. SOC. COMMUNICATIONS. Joachim Paier et al. , "Cu2ZnSnS4 as a potential photomaterial: A hybrid hatry-fock functional functional study", 2009/03/25, pages 115126-1 to 115126-8B, E Qijie Guo et al. , “Fabrication of 7.2% Efficient CZTSSe Solar Cells Using CZTS Nanocrystals”, 2010/11/19, pages 17384-17386, VOL. 132, NO. 49, J.M. AM. CHEM. SOC. COMMUNICATIONS. Shiyou Chen et al. , “Intrinsic point defects and complexs in the quarter kesterite semiconductor Cu2ZnSnS4”, 2010/06/08, pages 245204-1 to 245204-10, PHYSICAL RE81. Shiyou Chen et al. , “Compositional dependency of structural and electronic properties of Cu2ZnSn (S, Se) 4 alloys for thin film solar cells”, 2011/03/01, pages 125831Y, 125125E, 125125E, 125125E David B.B. Mitzi et al. "The path towers a high-performance solution-processed kesterite solar cell", 2011/01/17, pages 1421-1436, Solar Energy Materials & Solar Cells. Shannon C.I. Riha et al. , “Photoelectrochemical Charactorization of Nanocrystalline Thin-Film Cu2ZnSnS4 Photocathodes”, 2010/12/31, pages 58-66, VOL. 3, NO. 1, ACS Applied Materials & Interfaces. Grayson M.M. Ford et al. , “Earth Abundance Element Cu2Zn (Sn1-xGex) S4 Nanocrystallines for Tunable Band Gap Solar Cells: 6.8% Efficient Device Fabrication,” 2011/04 / 26-26. Tsuyoshi Maeda et al. , “First Principles Calculations of Defect Formation in In-Free Photovoltaic Semiconductors Cu2ZnSnS4 and Cu2ZnSnSe4P7-Jp7P20-20, pages04DP20, pages04DP20 J. et al. P. Leitao et al. , “Study of optical and structural properties of Cu2ZnSnS4 thin films”, 2010/12/25, pages 7390-7393, Thin Solid Films 519. Xiuying Wang et al. , “A facial general approach to primary semiconductor nanocrystals via a modified two-phase method”, 2011/04/21, cover page to pages 8 pages. Woseok Ki et al. , “Earth-Abundant Element Photovoltaics Directive from Solid Precursors with High Yield Using a Non-Toxic Solvent”, 2011/08/10, EDRI 73 G Mahaprasad Kar et al. "Formation Pathway of CuInSe2 Nanocrystals for Solar Cells", 2011/09/01, pages 17239-17247, JORNAL OF THE AMERICAN CHEMICAL SOCIETY. A Nagaya et al. , “Frist-principles study of Cu2ZnSnS4 and the related band offsets for Photovoltaic applications”, 2011/09/19, coverpage + pages 1 to 6, FOTEN. Manuel j. Romero et al. , "Comparative study of the luminescence and intrinsic point defects in the kesterite Cu2ZnSnS4 and chalcopyrite Cu (In, Ga) Se2 thin films used in photovoltaic applications", 2011/10/24, pages 165324-1~165324-5, PHYSICAL REVIEW B 84. M.M. Bar et al. , “Clip-like production band offset and KCN-induced recombination barrier enhancement at the CdS / Cu2ZnSnS4105-PlS11 / P11-S11-P11 P. M.M. P. Salome et al. , “The Inflation of Hydrogen in the Incorporation of Zn during the growth of Cu2ZnSnS4 thin films”, 2011/08/26, pages 3482-3489, Solar Energy Solar. Richard Height et al. , “Band alignment at the Cu2ZnSn (SxSe1-x) 4 / CdS interface”, 2011/06/21, Cover page + pages 253502-1 to 253502-3, APPLIED PHYSICS LETTERS 98.

  A method of forming a chalcogenide semiconductor film includes coating a precursor solution to form a layer on a substrate and annealing the layer to form a chalcogenide semiconductor film. The precursor solution has a solvent, metal chalcogenide fine particles, and at least one metal ion and metal complex ion dispersed on the surface of the metal chalcogenide fine particles. The metal of the metal chalcogenide fine particles, metal ions and metal complex ions is selected from the group consisting of Group I, Group II, Group III and Group IV elements of the Periodic Table and has all the metal elements of the chalcogenide semiconductor material.

  A method of forming a photovoltaic device includes: forming a lower electrode layer on a substrate; forming a chalcogenide semiconductor film on the lower electrode; forming a semiconductor layer on the chalcogenide semiconductor film; and a semiconductor layer Forming an upper electrode layer thereon. The chalcogenide semiconductor film is formed by coating a precursor solution so as to form a layer on the substrate. The precursor solution includes a solvent, metal chalcogenide fine particles, and at least one of metal ions and metal complex ions dispersed on the surface of the metal chalcogenide fine particles.

  The above and other objects, features and other advantages of the present invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings.

5 is a flowchart for adjusting ink forming a chalcogenide semiconductor film according to an embodiment of the present invention. It is a schematic diagram of an electronic double layer theory. 2 is an enlarged view of suspended metal chalcogenide fine particles of Example 1. FIG. 2 is an enlarged view of a plurality of metal chalcogenide fine particles covered with an electronic double layer of Example 1 and suspended in ink. FIG. 3 is a flowchart for forming a chalcogenide semiconductor film according to an embodiment of the present invention. 3 is an XRD analysis diagram of a CZTS film using the ink of Example 1. FIG. 6 is an XRD analysis diagram of a CZTS film using the ink of Example 2. FIG. 6 is an XRD analysis diagram of a CZTS film using the ink of Example 3. FIG. 6 is an XRD analysis diagram of a CZTS film using the ink of Example 6. FIG. 10 is an XRD analysis diagram of a CZTS film using the ink of Example 7. FIG. 3 is a flowchart of forming a photovoltaic device according to an embodiment of the present invention. It is a schematic diagram of the photovoltaic device formed by the method shown in FIG. It is a voltage-current characteristic view of a photovoltaic device in which a CZTS film is formed by using the ink of Example 7.

Definitions The following definitions are provided to facilitate understanding of certain terms used herein, but are not meant to limit the scope of the invention.

  “Chalkogen” refers to a group VIA element of the periodic table. Preferably, the term “chalcogen” refers to sulfur and selenium.

  The “chalcogenide compound” refers to a compound having at least one VIA group element in the periodic table.

  The “chalcogenide semiconductor film” refers to a two-component, three-component, and four-component chalcogenide compound semiconductor material in a broad sense. An example of a two-component chalcogenide compound semiconductor material is a IV-VI group compound semiconductor material. The ternary chalcogenide compound semiconductor material includes a group I-III-VI compound semiconductor material. Examples of the quaternary chalcogenide compound semiconductor material include a I-II-IV-VI group compound semiconductor material.

  The “IV-VI” group compound semiconductor material refers to a compound semiconductor material composed of group IVA elements and group VI elements in the periodic table, such as tin sulfide (SnS).

  “I-III-VI compound semiconductor material” refers to a compound semiconductor material composed of a group IB element, a group IIIA element, and a group VIA element of the periodic table, such as CIS or CIGS. The “I-II-IV-VI” group compound semiconductor material refers to a compound semiconductor composed of a group IB element, a group IIB element, a group IVA element and a group VIA element in the periodic table, such as CZTS.

“CIS” refers to a group I-III-VI compound semiconductor material in a broad sense. Preferably, the term “CIS” refers to, for example, copper indium selenide having the chemical formula CuIn (Se _x S _1-x ) ₂ (where 0 <x <1). The term “CIS” further includes indium selenide of copper having a fractional stoichiometric composition, such as, for example, CuIn (Se _0.65 S _0.35 ) ₂ .

“CZTS” refers to a group I-II-IV-VI compound semiconductor material in a broad sense. Preferably, the term “CZTS” refers to, for example, the chemical formula Cu _a (Zn _1-b Sn _b ) (Se _1-c S _c ) ₂ (where 0 <a <1, 0 <b <1, 0 ≦ x ≦ 1) Copper zinc tin sulfide and selenide. The term “CZTS” further includes zinc tin sulfide and selenides of copper having a fractional stoichiometric composition, such as, for example, Cu _1.94 Zn _0.63 Sn _1.3 S ₄ ). Further, the I-II-IV-VI group compound semiconductor material includes, for example, an I-II-IV-IV-VI group compound semiconductor material such as copper zinc tin germanium sulfide, a copper zinc tin germanium sulfide and the like. And I-II-IV-IV-VI-VI compound semiconductor materials such as selenides.

“CIGS” refers to a group I-III-VI compound semiconductor material in a broad sense. In one embodiment of the present invention, “CIGS” refers to, for example, copper indium gallium selenide having the chemical formula CuIn _x Ga _1-x S ₂ (where 0 <x <1). The term “CIGS” further includes indium gallium selenide of copper having a fractional stoichiometric composition such as, for example, Cu _0.9 In _0.7 Ga _0.3 Se ₂ .

  “Ink” refers to a solution having a precursor capable of constituting a semiconductor film. The term “ink” is also referred to as “precursor solution” or “precursor ink”.

  “Metal chalcogenide” refers to a compound composed of a group VI element and a metal in the periodic table. Preferably, the term “metal chalcogenide” refers to binary, ternary and quaternary metal chalcogenide compounds.

  “Ligand” refers to a molecule or ion surrounding a central metal ion. The ligand can form a bond that includes chemical and physical interactions with the central metal ion to form a metal complex ion.

  The “chalcogen-containing ligand” refers to a ligand having at least one group VI element in the periodic table.

  The “chalcogen-containing metal complex ion” refers to a metal complex ion having a chalcogen-containing ligand.

  A “chalcogen source” refers to a compound that forms a metal chalcogenide with a metal.

  “Fine particles” refers to particles having dimensions in the range of about 2 nm to 2000 nm.

Adjustment of Ink Forming Chalcogenide Semiconductor Film Referring to FIG. 1, a flow chart of adjusting ink forming a chalcogenide semiconductor film according to an embodiment of the present invention is shown.

  The method includes the step 110 of forming metal chalcogenide particulates. The metal chalcogenide fine particles can have only one type of metal chalcogenide fine particles and at least one type of metal chalcogenide fine particles. For example, the metal chalcogenide fine particles have a plurality of tin sulfide fine particles. In another embodiment, the metal chalcogenide fine particles include tin sulfide fine particles and copper sulfide fine particles. The metal chalcogenide fine particles can include multi-component metal chalcogenide fine particles such as copper tin sulfide fine particles. Furthermore, the metal chalcogenide fine particles can have fine particles each of which is composed of at least two metal chalcogenides. For example, the at least two metal chalcogenides are selected from the group consisting of tin chalcogenides, zinc chalcogenides, copper chalcogenides, indium chalcogenides and gallium chalcogenides.

  The process of forming the metal chalcogenide fine particles includes a step of dissolving a metal salt in a solution such as water so as to generate a first aqueous solution, and a case where a chalcogen source is dissolved in water so as to generate a second aqueous solution. And a step of mixing the first aqueous solution with the second aqueous solution so as to form metal chalcogenide fine particles. The treatment can further include changing the pH value of the mixed solution, stirring, and heating. In some embodiments, the mixed reaction solution is changed to a pH value within the range of about 7 to about 14. The metal chalcogenide microparticles have a particle size in the range of about 2 nm to 2000 nm.

  The metal salt has at least one metal selected from the group having groups IB, IIB, IIIB and IVA of the periodic table. In particular, the metal salt has at least one metal selected from the group comprising tin (Sn), copper (Cu), zinc (Zn), germanium (Ge), indium (In) and gallium (Ga). The metal salt can be, for example, tin chalcogenide, copper nitrate, zinc nitrate, gallium nitrate and indium chloride.

  Chalcogen sources include single or compositional precursors that are capable of generating sulfide or selenide ions in solution, such as thioacetamide, thiourea, selenourea, hydrogen sulfide, hydrogen selenide, There are sulfide-containing and selenide-containing compounds such as alkali metal sulfides or alkali metal selenides, selenium, sulfur, alkyl sulfides, alkyl selenides and diphenyl sulfides.

Examples of the metal chalcogenide fine particles include tin sulfide (Sn—S), copper sulfide (Cu—S), zinc sulfide (Zn—S), indium sulfide (In—S), gallium sulfide (Ga—S), and selenide. Tin (Sn-Se), copper selenide (Cu-Se), zinc selenide (Zn-Se), indium selenide (In-Se), gallium selenide (Ga-Se), copper tin sulfide (Cu -Sn-S), copper zinc sulfide (Cu-Zn-S), zinc tin sulfide (Zn-Sn-S), copper indium sulfide (Cu-In-S) copper gallium sulfide ( Cu-Ga-S), copper indium gallium sulfide (Cu-In-Ga-S), copper tin selenide (Cu-Sn-Se), copper zinc selenide (Cu-Zn-Se), zinc Tin selenide (Zn-Sn-Se), copper Jiumuseren compound (Cu-In-Se), there is a copper gallium selenide (Cu-Ga-Se) and copper indium gallium selenide (Cu-In-Ga-Se). The use of a hyphen (eg, “-” in Cu—S or Cu—Sn—S) indicates that the chemical formula covers all possible combinations of those elements, for example, “ CuS "is to cover CuS and Cu ₂ S. The stoichiometric composition of the metal and chalcogen can vary from a strict molar ratio, eg, 1: 1 or 1: 2. In addition, fractional stoichiometric compositions such as Cu _1.8 S are also included.

  Step 120 includes forming metal ions and / or metal complex ions. In step 120, either or both of metal ions and metal complex ions are prepared. The metal ions can be composed of only one kind of metal ions such as copper ions. In other embodiments, the metal ions can have two or more types of metal ions, such as copper ions and zinc ions. The metal of the metal ion and metal complex ion is selected from the group having groups IB, IIB and IVA of the periodic table.

  Metal ions are adjusted by dissolving a metal salt in a solvent such as water.

  The metal complex ion is obtained by dissolving a metal salt in water so as to generate a metal ion in the first aqueous solution, and dissolving a ligand in water so as to generate a second aqueous solution. It can be adjusted by mixing the first aqueous solution with the second aqueous solution to produce. For example, the metal complex ion can comprise a chalcogen-containing metal complex ion. The chalcogen-containing metal complex ion can be adjusted by mixing the metal ion and the chalcogen-containing ligand. Chalcogen-containing ligands include, for example, thioacetamide, thiourea or ammonium sulfide. The chalcogen-containing metal complex ions include metal-thiourea ions, metal-thioacetamide ions, or metal-ammonium sulfide ions.

  For example, the metal ions include copper ions, tin ions, zinc ions, germanium ions, indium ions, or gallium ions. Metal complex ions include copper-thiourea ion, tin-thiourea ion, germanium-thiourea ion, copper-thioacetamide ion, tin-thioacetamide ion, germanium-thiourea ion, indium-thiourea ion, gallium- There are thiourea ions, indium-thioacetamide ions and gallium thioacetamide ions.

  The metal chalcogenide particulates are present in the ink in an amount in the range of about 1% (w / v) to about 80% (w / v). Metal ions and / or metal complex ions are present in the ink in an amount in the range of about 0.5% (w / v) to about 80% (w / v).

  Step 130 includes mixing metal chalcogenide fine particles with metal ions and / or metal complex ions.

  It should be noted that step 110 can be performed before, after or at the same time as step 120. That is, the metal chalcogenide fine particles can be adjusted first, and then the metal ions and / or metal complex ions can be adjusted. In another embodiment, metal ions and / or metal complex ions can be prepared first, and then metal chalcogenide microparticles can be prepared. In other embodiments, metal chalcogenide microparticles and metal ions and / or metal complex ions are prepared in the same step.

  As noted above, both the metal chalcogenide particulates and the metal ions and / or metal complex ions can be included in one or more metals. In order to adjust the ink forming the chalcogenide semiconductor film, the metal chalcogenide fine particles and the metal of metal ions and / or metal complex ions contain all the metal elements of the chalcogenide semiconductor material. For example, the chalcogenide semiconductor metal material is selected from the group consisting of Group IV-VI compounds, Group I-III-VI compounds, and Group I-II-IV-VI compounds. For example, at least three metals, ie, at least one metal element of group IB, at least one metal element of group IIB, and at least one metal of group IVA of the periodic table, so as to adjust the ink forming the CZTS film Contains elements. In some embodiments, at least three metals are used in steps 110 and 120, respectively, and can all be included in the solution obtained in step 130. In other cases, the metal chalcogenide microparticles and the metal ions and / or metal complex ions can each have only one metal. Accordingly, only two metals are included in the solution obtained in step 130. Accordingly, the method includes determining 140 whether the metal chalcogenide particulates and the metal of the metal ion and / or metal complex ion include all metals of the chalcogenide semiconductor material. If not all metals are included, the above steps are repeated. For example, the step 120 of generating metal ions and / or metal complex ions is repeated to include a third metal in the ink. In other embodiments, the step 110 of forming metal chalcogenide particulates is repeated to have a third metal in the ink.

  In step 150, ink is formed.

  In the above treatment, water is used as a solvent. However, in other embodiments, the solvent comprises a polar solvent such as alcohol, dimethyl sulfoxide (DMSO), or amine. Examples of alcohols are methyl alcohol, ethyl alcohol or isopropyl alcohol.

  Furthermore, in some embodiments, step 120 and step 130 can be repeated multiple times to add additional metal ions and / or metal complex ions. In order to explain the characteristics of the ink of the present invention, the theory of an electronic double layer will be briefly described. FIG. 2 is a schematic diagram of the electronic double layer theory. In FIG. 2, the fine particles 210 are suspended in the solvent 220. The microparticle 210 has a negatively charged surface 230. Accordingly, positive ions 240 are absorbed by the negatively charged surface 230 of the microparticles 210 due to electrostatic forces. Some of the positive ions 240 are densely absorbed by the negatively charged surface 230 and are referred to as the stern layer 250, while some of the positive ions 240 are accompanied by a concentration at which the stern layer 250 decreases. Surrounding and called the diffusion layer 260. The stern layer 250 and the diffusion layer 260 constitute an electron double layer 270. Since the fine particles 210 are surrounded by the electric double layer 270, the fine particles 210 are repelled from the other fine particles 210 by the electrostatic repulsion force provided by the electric double layer 270. Accordingly, the microparticles 210 can be suspended in the solution 220.

  Similarly, in this embodiment, the metal chalcogenide microparticles are also covered with metal ions and / or metal complex ions and are therefore suspended in the solution. Thus, the ink is well dispersed particles and can be used to form a chalcogenide semiconductor film.

  Hereinafter, a plurality of embodiments for adjusting the ink for forming the CZTS film and the CIGS film will be described in detail.

Example 1
Adjustment of ink forming CZTS film Adjustment of metal chalcogenide fine particles. 5 mmol of tin chloride is dissolved in 25 ml of H ₂ O to produce an aqueous solution (A1). 4 mmol of thioacetamide is dissolved in 40 ml of H ₂ O to produce an aqueous solution (B1). These aqueous solutions (A1) and (B1) are mixed to form a reaction solution (C1). To the reaction solution (C1), 12 ml of 30% NH ₄ OH is added and it is stirred at 65 ° C. for 1.5 hours. The resulting dark brown precipitate is collected to provide tin sulfide (Sn—S) particulates.

Adjustment of metal complex ions. 7 mmol of copper sulfate is dissolved in 5 ml of H ₂ O to produce an aqueous solution (D1). 10 mmol of thioacetamide is dissolved in 5 ml of H ₂ O to produce an aqueous solution (E1). These aqueous solutions (D1) and (E1) are mixed to form a reaction solution (F1). The reaction solution (F1) is stirred at room temperature for 0.5 hour to form copper thioacetamide ions.

  The collected tin sulfide (Sn—S) fine particles are mixed with the reaction solution (F1) so as to form a mixed solution (G1).

Adjustment of metal ions. 4.8 mmol of zinc sulfate is dissolved in 5 ml of H ₂ O to produce an aqueous solution (H1) containing zinc ions.

  The aqueous solution (H1) is mixed with the mixed solution (G1) and stirred overnight to produce ink.

  FIG. 3 is an enlarged view of suspended tin sulfide (Sn—S) fine particles of the example. As shown in FIG. 3, tin sulfide (Sn—S) particulates 310 have a negatively charged surface 320. Both the copper thioacetamide ion 330 and the zinc ion 340 are positively charged and are absorbed by the negatively charged surface 320 of the tin sulfide (Sn—S) microparticles 310 by electrostatic force.

  4 shows an enlarged view of a plurality of metal chalcogenide fine particles covered with an electronic double layer and suspended in ink in Example 1. FIG. In FIG. 4, a plurality of tin sulfide (Sn—S) fine particles 410 suspended in the solvent 420 exist. Each of the tin sulfide (Sn—S) particulates 410 has an outer surface 430 that is negatively charged. In addition, copper thioacetamide ions 440 and zinc ions 450 are generated in the ink 420. Positively charged copper thioacetamide ions 440 and zinc ions 450 are absorbed by the negatively charged outer surface 430 of the tin sulfide (Sn—S) particulates 410. Each tin sulfide (Sn—S) fine particle 410 is surrounded by a plurality of positive ions, and they are repelled from each other. Accordingly, the tin sulfide (Sn—S) fine particles 410 are dispersed and suspended in the solvent 420.

Since each tin sulfide (Sn—S) fine particle is covered with copper thioacetamide ions and zinc ions, four elements of the quaternary compound semiconductor CZTS (Cu ₂ ZnSnS ₄ ), that is, copper, zinc, tin And sulfur are in close proximity to each of the Sn-S particulates. Thus, the ink is a good mix of copper, zinc, tin and sulfur and can be used to form a CZTS film.

Example 2
In this embodiment, there are two types of metal chalcogenide fine particles prepared in the ink, that is, one metal chalcogenide fine particle has SnS fine particles and Cu complex / ion, and the other metal chalcogenide fine particles are ZnS fine particles. Thus, it is different from the first embodiment.

Adjustment of metal chalcogenide fine particles. 5 mmol tin chalcogenide is dissolved in 40 ml H ₂ O to produce an aqueous solution (A2). 4 mmol of thioacetamide is dissolved in 40 ml of H ₂ O to produce an aqueous solution (B2). The aqueous solutions (A2) and (B2) are mixed to produce a reaction solution (C2). 10 ml of 30% NH ₄ OH is added to the reaction solution (C2) and stirred at 65 ° C. for 1.5 hours. At that time, tin sulfide fine particles are precipitated as black-brown particles in the reaction solution (C2).

Adjustment of metal complex ions and metal ions. 7 mmol of copper nitrate is dissolved in 5 ml of H ₂ O to produce an aqueous solution (D2). 5 mmol of thioacetamide is dissolved in 5 ml of H ₂ O to produce an aqueous solution (E2). The aqueous solutions (D2) and (E2) are mixed to produce a reaction solution (F2). The reaction solution (F2) is stirred at room temperature for 0.5 hour to produce copper thioacetamide ions and copper ions.

  Tin sulfide fine particles are mixed with the reaction solution (F2) to produce a mixed solution (G2).

Adjustment of metal ions. 4.8 mmol zinc nitrate is dissolved in 5 ml H ₂ O to produce an aqueous solution (H 2) containing zinc ions.

  The mixed solution (G2) is mixed with the aqueous solution (H2) and stirred for 10 minutes to form a mixed solution (I2).

  Metal chalcogenide and ink formation. 29 mmol of ammonium sulfide is added to the mixed solution (I2) and stirred overnight to form an ink.

Example 3
This example differs from Example 2 in that two types of metal chalcogenide fine particles are dispersed with different component metal ions and / or metal complex ions.

Adjustment of metal chalcogenide fine particles. 2.5 mmol tin chalcogenide is dissolved in 25 ml H ₂ O to produce an aqueous solution (A3). 2 mmol of thioacetamide is dissolved in 25 ml of H ₂ O to produce an aqueous solution (B3). The aqueous solutions (A3) and (B3) are mixed to produce a reaction solution (C3). The reaction solution (C3) is added with 10 ml of 30% NH ₄ OH and stirred at 65 ° C. for 1.5 hours. At that time, tin sulfide (Sn—S) fine particles are precipitated as black-brown particles in the reaction solution (C3).

Adjustment of metal complex ions and metal ions. 3.8 mmol of copper nitrate is dissolved in 5 ml of H ₂ O to produce an aqueous solution (D3). 3 mmol of thioacetamide is dissolved in 5 ml of H ₂ O to produce an aqueous solution (E3). The aqueous solutions (D3) and (E3) are mixed to produce a reaction solution (F3). The reaction solution (F3) is stirred at room temperature for 0.5 hour to produce copper thioacetamide ions and copper ions.

  Tin sulfide (Sn-S) fine particles are mixed with the reaction solution (F3) to form a mixed solution (G3).

Preparation of metal ions and metal chalcogenide fine particles. 2.8 mmol of zinc nitrate is dissolved in 5 ml of H ₂ O to produce an aqueous solution (H3). 22 mmol of ammonium sulfide is dissolved in the aqueous solution (H3) to form a reaction solution (I3).

  The mixed solution (G3) is mixed with the aqueous solution (I3) so as to form ink.

Example 4
This example differs from Example 1 in that the fine particle precursor is formed before the formation of the metal chalcogenide fine particles.

  Adjustment of the fine particle precursor. Stir overnight so that 2.5 mmol of tin sulfide (Sn-S) and 2 mmol of sulfur (S) are dissolved in 5 ml of 40-50% ammonium sulfide to form the reaction solution (A4). Is done.

Adjustment of metal complex ions and metal ions. 3.8 mmol of copper nitrate is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (B4). 4.0 mmol of thioacetamide is dissolved in 6 ml of H ₂ O to produce an aqueous solution (C4). The aqueous solution (B4) and the aqueous solution (C4) are mixed and stirred at room temperature for 20 minutes to produce a reaction solution (D4).

  The reaction solution (A4) is mixed with the reaction solution (D4) to produce a mixed solution (E4).

Adjustment of metal ions. 2.8 mmol of zinc nitrate is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (F4).

  The mixed solution (E4) is mixed with the aqueous solution (F4) and stirred overnight to form an ink.

Example 5
This example differs from Example 4 in that copper thiourea complex ions are formed in the ink.

  Adjustment of the fine particle precursor. 2.5 mmol of tin sulfide is dissolved in 5 ml of 40-50% thiourea aqueous solution and stirred overnight to form reaction solution (A5).

Adjustment of metal complex ions and metal ions. 3.8 mmol of copper nitrate is dissolved in 5 ml of H ₂ O to produce an aqueous solution (B5). 5.9 mmol of thiourea is dissolved in 5 ml of H ₂ O and stirred for 20 minutes at room temperature to produce a reaction solution (D5).

  The reaction solution (A5) is mixed with the reaction solution (D5) to produce a mixed solution (E5).

Preparation of metal ions and metal chalcogenide fine particles. 2.8 mmol of zinc nitrate is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (F5). 33 mmol of ammonium sulfide is dissolved in the aqueous solution (F5) to form a reaction solution (G5).

  The mixed solution (E5) is mixed with the reaction solution (G5) and stirred overnight to form an ink.

Example 6
This example differs from Example 1 in that bimetallic ions and / or metal complex ions are adjusted before formation of metal chalcogenide fine particles.

Adjustment of the first metal ion. 1.07 mmol of tin chloride is dissolved in ₂ ml of H ₂ O and stirred for 5 minutes to produce an aqueous solution (A6).

Adjustment of the second metal ion. 1.31 mmol of zinc sulfide is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (B6).

  The aqueous solution (A6) is mixed with the aqueous solution (B6) and stirred for 15 minutes to form an aqueous solution (C6).

Adjustment of metal complex ions. 1.7 mmol of copper sulfate is dissolved in 1.5 ml of H ₂ O to produce an aqueous solution (D6). 3 mmol of thiourea is dissolved in 3 ml of H ₂ O to produce an aqueous solution (E6). The aqueous solution (D6) is mixed with the aqueous solution (E6) and stirred at room temperature for 20 minutes to produce a reaction solution (F6).

  The aqueous solution (C6) is mixed with the reaction solution (F6) and stirred for 10 minutes to produce a mixed solution (G6). In some embodiments, the mixed solution (G6) can be stirred at a temperature of about 60 ° C.

  Addition of metal chalcogenide fine particles and ink. 1.5 mmol of 40-50% aqueous ammonium sulfide is added to the mixed solution (G6) and stirred overnight or ultrasonically for 30 minutes to produce ink.

Example 7
This example differs from Example 6 in that selenium is included in the ink.

Adjustment of the first metal ion. 1.07 mmol of tin chloride is dissolved in ₂ ml of H ₂ O and stirred for 5 minutes to produce an aqueous solution (A7).

Adjustment of the second metal ion. 1.31 mmol of zinc nitrate is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (B7).

  Aqueous solution (A7) is mixed with aqueous solution (B7) and stirred for 15 minutes to produce aqueous solution (C7).

Adjustment of metal complex ions. 1.7 mmol of is dissolved in 1.5 ml of H ₂ O to produce an aqueous solution (D7). 3 mmol of thiourea is dissolved in 3 ml of H ₂ O to produce an aqueous solution (E7). The aqueous solution (D7) and the aqueous solution (E7) are mixed and stirred at room temperature for 20 minutes to produce a reaction solution (F7).

  The aqueous solution (C7) is mixed with the reaction solution (F7) and stirred for 10 minutes to produce a mixed solution (G7). In some embodiments, the mixed solution (G7) can be stirred at a temperature of about 60 ° C.

  Formation of metal chalcogenide fine particles, metal complex ions and ink. 0.1 g of selenium (Se) particles are dissolved in 1 ml of 40% to 50% aqueous ammonium sulfide solution to form an aqueous solution (H7). The aqueous solution (H7) is added to the mixed solution (G7) and stirred overnight or ultrasonically for 30 minutes to form ink.

  Examples 1 to 7 are methods for adjusting ink for forming a CZTS film. Hereinafter, the Example which adjusts the ink for forming a CIGS film | membrane is explained in full detail.

Example 8
Adjustment of ink to form CIGS film Adjustment of first metal ion. 0.5 mmol of gallium nitrate is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (A8).

Adjustment of the second metal ion. 0.5 mmol of indium chloride is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (B8).

  The aqueous solution (A8) is mixed with the aqueous solution (B8) and stirred for 15 minutes to produce a mixed solution (C8).

Adjustment of metal complex ions. 1.0 mmol of copper nitrate is dissolved in ₂ ml of H ₂ O to produce an aqueous solution (D8). 5.9 mmol of thiourea is dissolved in 5 ml of H ₂ O to produce an aqueous solution (E8). The aqueous solution (D8) is mixed with the aqueous solution (E8) and stirred at room temperature for 20 minutes to produce a reaction solution (F8).

  The aqueous solution (C8) is mixed with the reaction solution (F8) and stirred for 10 minutes to produce a mixed solution (G8). In some embodiments, the mixed solution (G8) can be stirred at a temperature of about 60 ° C.

  Formation of metal chalcogenide fine particles and ink. 1.5 mmol of 40-50% aqueous ammonium sulfide is added to the mixed solution (G8) and stirred overnight or ultrasonically for 30 minutes to produce ink.

Formation of Chalcogenide Semiconductor Film by Using Precursor Solution Referring to FIG. 5, a flow chart for forming a chalcogenide semiconductor film according to an embodiment of the present invention is shown.

  The method includes preparing 510 a precursor solution having metal chalcogenide microparticles and at least one metal ion and metal complex ion. The precursor solution can be prepared by the process shown in FIG.

  Step 520 comprises coating the substrate with the precursor solution so as to form a liquid layer of the precursor solution on the substrate. The coating method includes a drop casting method, a spin coating method, a dip coating method, a doctor blade method, a curtain coating method, a slide coating method, a spray method, a slit coating method, a meniscus coating method, a screen printing method, an ink jet printing method, a pad. There are printing methods, flexographic printing methods, and gravure printing methods, but not limited thereto. The substrate can be hard such as a glass substrate, or can be flexible such as a metal foil or a plastic substrate. In some embodiments, the substrate is formed with a molybdenum (Mo) layer prior to coating the precursor solution.

  Step 530 includes drying the liquid layer of the precursor solution so as to form a precursor film. During the drying process, the solvent is removed by evaporation. The drying method can be performed, for example, by placing the substrate in a furnace, in an oven, or on a hot plate. While a precursor solution of CZTS film is used, the drying process can be performed at a temperature in the range of about 25 ° C. to 600 ° C., preferably in the range of 350 ° C. to 480 ° C. Most preferably, the drying temperature is about 425 ° C. The coating step and the drying step can be repeated two or more times, for example, about 3 to about 6 times. The resulting precursor film has a thickness of, for example, about 1 to 5000 nm.

  Step 540 includes annealing the precursor film to form a chalcogenide semiconductor film. The annealing temperature of the CZTS precursor film is in the range of about 300 ° C. to 700 ° C., and preferably in the range of 480 ° C. to 650 ° C. Most preferably, the temperature is 540 ° C. In this embodiment, the annealing process can be performed at a temperature of about 540 ° C. for 10 minutes. In some embodiments, the annealing process can be performed under an atmosphere containing sulfur vapor.

  The inks prepared in Examples 1 to 3 and Examples 6 and 7 are used as a precursor solution for forming a CZTS film. The CZTS film is configured to have a chalcopyrite structure by XRD analysis shown in FIGS.

Manufacturing of Photovoltaic Device Referring to FIG. 11, a flow chart for forming a photovoltaic device according to an embodiment of the invention is shown. Also, referring to FIG. 12, it is a schematic diagram of a photovoltaic device formed by the method shown in FIG.

  The method includes a step 1110 of forming a lower electrode layer 1210 on the substrate 1200. For example, the substrate 1200 comprises a material selected from the group comprising glass, metal foil and plastic. The lower electrode 1210 includes a material selected from the group including molybdenum (Mo), tungsten (W), aluminum (Al), and ITO (Indium Tin Oxide). In this embodiment, the Mo layer 1210 is formed on the substrate by sputtering.

  Step 1120 includes forming a chalcogenide semiconductor film 1220 on the lower layer 1210 by using a precursor solution. The precursor solution can be prepared by the process shown in FIG. In this embodiment, the CZTS film is formed as the chalcogenide semiconductor film 1220. The CZTS film 1220 formed on the Mo layer 1210 has a film thickness in the range of about 0.6 μm to about 6 μm.

Step 1130 includes forming a buffer layer 1230 on the chalcogenide semiconductor film 1220. The buffer layer includes a semiconductor layer such as an n-type semiconductor layer or a p-type semiconductor layer. For example, the buffer layer includes cadmium sulfide (CdS), Zn (O, OH, S), indium sulfide (In ₂ S ₃ ), zinc sulfide (ZnS), and zinc oxide magnesium (Zn _x Mg _1-x O). Having a material selected from the group. In the present embodiment, the CdS layer 1230 is formed as an n-type semiconductor layer on the CZTS film 1220. The CdS film 1230 can be formed by a chemical bath deposition method. In the present embodiment, the film thickness of the CdS film 1230 can be in the range of about 20 nm to about 150 nm, for example.

  Step 1140 includes forming an upper electrode 1240 on the buffer layer 1230. The upper electrode has a transparent conductive layer. For example, the upper electrode layer 1240 includes zinc oxide (ZnO), ITO (Indium Tin Oxide), boron-doped zinc oxide (B-ZnO), aluminum-doped zinc oxide (Al-ZnO), and gallium-doped zinc oxide (Ga--). ZnO) and a material selected from the group comprising antimony tin oxide (ATO). In this embodiment, zinc oxide (ZnO) with a thickness of about 100 nm and ITO (Indium Tin Oxide) with a thickness of about 130 nm are formed as the upper electrode layer 1240 on the buffer layer 1230. The method of forming the ZnO film and the ITO film can be, for example, sputtering.

  Step 1150 includes forming a metal contact 1250 on the upper electrode layer 1240. The metal contact 1250 can be formed as nickel (Ni) / aluminum (Al). The method of forming the Ni / Al metal contact 1250 can be, for example, electron beam evaporation.

Step 1160 includes forming an antireflection film 1260 on the substrate 1200. For example, the antireflective coating comprises a material selected from the group comprising magnesium fluoride (MgF ₂ ), silicon dioxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ) and niobium oxide (NbO _x ). In this embodiment, MgF ₂ 1260 is formed on the substrate as an antireflection film. The MgF ₂ film can be formed by, for example, electron beam evaporation. In the present embodiment, the film thickness of the magnesium fluoride (MgF ₂ ) film can be 110 nm, for example. In that case, a photovoltaic device is formed.

FIG. 13 is a diagram illustrating voltage-current characteristics of a photovoltaic device in which a CZTS film is formed by using Example 7. The device has a power conversion efficiency of 2.7% under 1.5AM standard lighting conditions with an open circuit voltage (Voc) = 450 mV, a fill factor (FF) = 40.9% and a short circuit current density (Jsc). = is measured as having 14.8mA / cm ^2.

Claims (11)

A method of forming a chalcogenide semiconductor film comprising:
Coating a precursor solution to form a layer on a substrate, the precursor solution comprising a solvent, metal chalcogenide particles, and metal ions and metal complex ions dispersed on a surface of the metal chalcogenide particles; at least one have a, at least one of the metal ions and metal complex ions are positive ions are densely absorbed on the surface of the metal chalcogenide particles which are negatively charged, the metal chalcogenide fine particles charged to the negative Forming an electric double layer with the surface of the metal and the positive ions ; and annealing the layer to form the chalcogenide semiconductor film, the metal chalcogenide fine particles, the metal ions, and the metal complex ions The metals of the Periodic Table have groups I, II, III and IV. Having all metal elements of the chalcogenide semiconductor material selected from the group of:
Having a method.   The step of coating the precursor solution includes wet coating, printing, spin coating method, dip coating method, doctor blade method, curtain coating method, slide coating method, spray method, slit coating method, meniscus coating method, screen printing method, The method according to claim 1, comprising an inkjet printing method, a pad printing method, a flexographic printing method, or a gravure printing method.   The method of claim 1, further comprising drying the layer at a temperature in the range of about 25 ° C. to about 700 ° C.   The method of claim 1, wherein the annealing is performed at a temperature within a range of about 300 ° C. to about 700 ° C. 5.   The method according to claim 1, wherein the metal of the metal chalcogenide fine particles, the metal ion, and the metal complex ion include tin, copper, and zinc.   The method of claim 1, wherein the metal of the metal chalcogenide fine particles, the metal ion, and the metal complex ion further comprises germanium.   The method according to claim 1, wherein a metal of the metal chalcogenide fine particles, the metal ion, and the metal complex ion includes copper, indium, and gallium.   The method of claim 1, comprising forming a chalcogenide semiconductor film selected from the group comprising a group IV-VI compound, a group I-III-VI compound and a group I-II-IV-VI compound. Method. A method of forming a photovoltaic device comprising:
Forming a bottom electrode layer on the substrate;
Forming a chalcogenide semiconductor film on the lower electrode according to the method of claim 1;
Forming a semiconductor layer on the chalcogenide semiconductor film; and forming an upper electrode layer on the semiconductor film;
Having a method.   The method of claim 9, wherein forming the semiconductor layer comprises forming an n-type semiconductor layer.   The method of claim 9, wherein forming the top electrode comprises forming a transparent conductive layer.

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