TW201115773A - Method of manufacturing absorption layer of solar cells and its structure - Google Patents

Abstract

Disclosed is a method of manufacturing absorption layer of solar cells and its structure. According the method, a substrate of the solar cells is provided, and a copper-rich first coating and a copper-poor second coating are formed on the substrate by printing in order. A selenization heat treatment is provided, and the first coating and the second coating are sintered to form a compact CIGS film with large grains. Because the first coating has the lower melting point than the second coating, the first coating is firstly forming liquid phase. The internal stress of binding sinter is reduced by the liquid-phase sintering to increase the conversion efficiency of the solar cells. Furthermore, the vacuum process is replaced by size-coating process to increase the output and to reduce the production costs.

Description

201115773 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a solar coating, particularly to a method and structure for fabricating an absorption layer of a solar cell. [Prior Art] In the solar cell industry, the copper indium gallium selenide (CIGS) series is thin.

Compared with the effect of photocracking of amorphous Aussie thin-film solar cells, the film light m cow is the most efficient one. The stability and radiation resistance characteristics of the cIGS thin film photovoltaic elements are highly recommended. The main practice in the current industry of cigs thin film solar cells is to use sodium glass as the substrate, metal molybdenum (Mo) as the back electrode, and then the CIGS absorber layer is formed by co-evaporation or sputtering on the M electrode. CIGS (CuIn (Ja/Se^ is a p-type semiconductor, mainly responsible for the role of absorbing light energy in components. Today's method for making copper-germanium gallium selenide absorber layer is mainly vacuum process, including vapor deposition method and sputtering method. In fact, the technology for fabricating the absorbing layer of copper indium gallium selenide film by vacuum process is mature, and the components produced have a relatively high conversion rate. However, the process of depositing the film must be carried out in a vacuum environment, not only The cost of the equipment is expensive and the use of raw materials in the process is not economical. It is easy to cause unevenness of the film product during the process enlargement. In order to overcome the above problems, many scholars have actively researched and developed non-vacuum processes, including electroplating deposition and spray heat. A solution method and a slurry coating method, wherein the slurry coating method directly uses the herbicide naphtha as a raw material, and prepares the code through the #system process. Steel film can greatly reduce the production cost of thin film solar cells, and 201115773 can reduce the problem of uneven film composition during selenization heat treatment. However, the biggest problem in this process is the selenization heat treatment process. Effectively grows, does not achieve the effect of film densification. Such as $

As shown in Fig. 1, since the conventional slurry coating method directly coats an absorbing layer 140 on the glass substrate 110, the internal stress of the restrained sintering of the CIGS absorbing layer 140 is generated during the selenization heat treatment, and is in CI. (The tensile stress T is generated on both sides of the js absorption layer 140, so that the CIGS absorption layer 14〇 cannot effectively grow the crystal grains, and the pores 14 1 or the cracks 1 42 are generated in the CIGS absorption layer 140, so that the film densification cannot be achieved. The result (as shown in Fig. 2), so that the conversion rate of solar cells is low. At present, in this industry, the main manufacturer of copper-plated steel and solar cells developed by the polymer coating method is Nanosolar, and its technology is used. It is a roll-to-roll mass production process that directly applies copper indium gallium selenide to an aluminum foil substrate to form a flexible solar cell. The process patent technology is as follows: Manufacturer Name: Nanosolar US Patent Application No. 20060062902 Synthesize a powder of a double-shell structure with elemental powders of I, III, VI, < is to use Cu as a core, respectively, and inject it to the surface of In, Ga, and uniformly disperse backward Selenization heat treatment 20060207644 The water particles are uniformly mixed with the nanoparticles of each element, and a dispersant and a binder are added to prepare an aqueous slurry, and the ratio between In and Ga is adjusted to adjust the energy gap value, and the reaction is carried out under an appropriate temperature atmosphere. 20070166453 Coating a layer of Cu-In-Ga alloy on the substrate, and then covering the alloy with VI element, and forming a film thickness of 〇5~4.0/nn after heat treatment at 375 °C. 201115773 20071063639 First synthesis of the lack of habitat Binary composition (Cu_Se, chemical-free or - know) micro-plate 'and fills the voids by adding VI element, and then selenium-rich particles are attached to the upper layer to diffuse to achieve uniform and dense film. 20070163644 20070092648 Compounds of Groups I-VI, III-VI, I-III-VI are used as precursor powders, followed by addition of VI for mixing or coating, and heat treatment at 370 ° C to 500 ° C to obtain a dense film. The binary compound (CuSe, InSe, GaSe) is formed by blending, and is heat-treated at a temperature above the melting temperature to obtain a film of uniform composition I-III-VI. [Invention] In order to solve the above problems, the present invention The main purpose of the invention is to provide a method and structure for fabricating an absorption layer of a solar cell, which reduces the internal stress of the bound sintering by liquid phase sintering, thereby forming a dense and large-grained copper indium gallium selenide (CIGS) film. Increasing the conversion rate of the solar cell. The second object of the present invention is to provide a method and structure for manufacturing a solar cell absorbing layer, which is a non-vacuum slurry coating process, which can reduce the amount of raw materials used and eliminate the use of vacuum coating. The machine's success • This can increase overall production and significantly reduce production costs. The purpose of Ming and its technical problems are solved by the following technical solutions. The invention discloses a method for manufacturing an absorption layer of a solar cell, which mainly comprises the following steps: a method for manufacturing an absorption layer of a solar cell, comprising: providing a solar cell substrate. Forming a first slurry on the solar cell substrate, the first slurry comprising a copper-rich powder, an organic solvent, and a dispersing agent, and the chemical formula of the copper-rich powder is Cuyl(InxGal-x)(SeS)2 or Cu2- zSe, wherein yl > 1, 〇.4$χ SO.8, and the first drying is performed to remove the first slurry [201115773] so that the first slurry is formed into a -th coat. The first slurry is formed on the first coating layer, and the chemical system containing the copper-deficient powder, the organic solvent and the dispersing agent is CUy2(InxGal_x)(SeS)2, wherein And 〇.4Sx^〇8 — —, the first person is dried to remove the second slurry organic solvent, and the 兮篦_ «Μ first pulp is formed into a second coating. Heat treatment, the first coating and the second coating are performed with 焯钍,

A copper indium gallium selenide film which is dense and has a large crystal grain size. Since the copper-rich powder phase has a lower melting point in the copper-deficient powder, the first coating first forms a liquid phase: the liquid phase is sintered to reduce the bondage. Internal stress during sintering. The present invention further discloses the structure of the solar cell absorber layer formed by the method of the above description. The object of the present invention and solving the technical problems thereof can be further realized by the following technical measures. In the above method for producing a solar cell absorber layer, the organic 'mixtures' may be selected from the group consisting of toluene, gas (ehl_fQrm), dimethylamine (N'N-Dimethylf0rmamide), dimethyl sulfoxide ( Dimethyi sulfoxide) and one of the pyridines. In the aforementioned method for producing a solar cell absorbing layer, the dispersing agents may be selected from the group consisting of oleylamine, alkyl selenyl, alkylthiol, and aromatic selenol ( Aromatic selenol) and aromatic thiol. In the above method for manufacturing a solar cell absorbing layer, the first polymer and the second slurry may each further comprise a binder for adjusting the viscosity and film forming property of the polymer. 201115773 In the aforementioned method for producing a solar cell absorbing layer, the binder may be selected from one of dihydroterpineol and polyvinyl butyral. In the foregoing method for manufacturing a solar cell absorbing layer, after drying the second slurry and before the selenization heat treatment, the method may further include: heat treating the first coating layer and the second coating layer to remove the Adhesive. In the above method for producing a solar cell absorbing layer, the first slurry and the second slurry may be formed in a printing manner. In the above-described method for producing a solar cell absorbing layer, the copper-rich powder and the copper-deficient powder are nano-sized powders having a particle size distribution of up to 1 奈 nanometer (nm). In the above method of manufacturing a solar cell absorbing layer, the first coating layer and the second coating layer may have the same thickness. In the above method for manufacturing a solar cell absorbing layer, the solar cell substrate may be a glass substrate, and a metal layer is formed on the surface, and the material of the metal layer is molybdenum. It can be seen from the above technical solutions that the manufacturing method and structure of the solar cell absorbing layer of the present invention have the following advantages and effects: by forming the first coating layer, forming the second coating layer and performing the selenization heat treatment as one of the technologies Means, because the copper-rich powder has a lower melting point relative to the copper-deficient powder, so that the first coating layer first forms a liquid phase, the liquid phase sintering is used to reduce the internal stress of the bound sintering to form a dense and large grain-copper. Indium gallium selenide film to increase the conversion rate of solar cells. 201115773 Second, by forming the first coating and the second coating as one of the technical means, because it is a non-vacuum slurry coating process, in addition to reducing the amount of raw materials used and eliminating the cost of using a vacuum coating machine , which can increase the overall output and thus significantly reduce production costs. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, in which Therefore, only the components and combinations related to the case are shown. The components shown in the figure are not drawn in proportion to the actual number, shape and size of the actual implementation. Some ratios of dimensions and other related dimensions are either exaggerated or simplified. To provide a clearer description. The actual number, shape and size ratio of the implementation is an optional design, and the detailed component layout may be more complicated. According to an embodiment of the present invention, a method of manufacturing a solar cell absorbing layer is exemplified in the block diagram of Fig. 3 and the component wearing diagrams of Figs. 4 to 4F. The method for manufacturing the solar cell absorbing layer according to FIG. 3 includes the following steps: "Steps for providing a solar cell substrate", "Step 2 of forming a first material on a solar cell substrate", "Drying to remove the first" The organic solvent of the slurry is formed into a first coating step 3, "forming a second charge on the first coating layer" to "dry to remove the organic solvent of the second slurry to form a second coating layer ^ heat treatment of the first coating and the second coating to remove the binder": step 6 and "the selenization heat treatment to sinter the first coating and the second coating of the steel indium gallium nitride film" step 7, detailed For the procedure, please refer to the policy 201115773 4A to 4F. The description is as follows. First, 'provide a solar cell substrate 21〇 as shown in Fig. 4'. Specifically, the solar cell substrate 21 can be a glass substrate, and a metal layer 211 is formed on the surface, and the material of the metal layer 211 is molybdenum (Mo). In a preferred embodiment, the metal layer is formed by sputtering and has a thickness of about 1 micron (μm). As shown in Fig. 4, a first slurry 22 is formed on the solar cell substrate 210. The first slurry 22 contains a copper-rich powder organic solvent and a dispersant, and the chemical formula of the copper-rich powder 221 is

Cuyl(inxGai.x)(SeS)2 or Cu2.zSe ' where yi> 1, 〇.4$χ$ Ο.8 and more specifically, the first paste 220 can be printed by a screen printing machine to The solar cell substrate 2 10 is on the metal layer 2 ij . Next, as shown in Fig. 4C, the first drying is performed to remove the organic solvent of the second material 220, and the first slurry 220 is formed into the first coating layer 22A. In this embodiment, since the organic solvent of the first slurry 22 can be partially or completely removed, the first slurry 220 is more gelatinized and partially cured, and after drying, the thickness is about The first coating 22A is 2 to 3 microns (in m). Further, as shown in FIG. 4D, after the first slurry 220 is dried, a second slurry 230 is formed on the first coating layer 22A, and the second forging angle 230 # ^ a ^ "^ 3 is missing. The steel powder is 23 丨, the organic solvent and the dispersing agent, and the chemical formula of the steel-deficient steel 3 1 is CuysGnxGahKSeSh, wherein y2 < 10 Λ 客 0.8. In the present embodiment, the second slurry 23 〇 and the 201115773 a slurry The material 220 can be formed by printing. Specifically, the so-called copper-deficient powder 231 of the present invention is not completely free of copper, but only has a low copper content. Further, the organic solvent may be selected from toluene. , chloroform, dimethyl-dimethylformamide, dimethyl sulfoxide and pyridine, mainly used to mix copper-rich powder 221 with copper deficiency The powder 231 is formed into the first slurry 220 and the second slurry 230, respectively, and the dispersing agent may be selected from the group consisting of oleylamine, aylylsenoi, and alkylsulfide. Alkylthi〇l), aromatic selenol and aromatic sulfur (ar0ma One of tic thi〇1) mainly functions to uniformly disperse the copper-rich powder 221 and the copper-deficient powder 231 in the mixed organic solvent. Further, the first slurry 220 and the second slurry 230 are respectively Containing a bit of a knot to adjust the viscosity and film formability of the slurry. In this embodiment, the binder may be selected from the group consisting of ethyl cellulose (dihydr〇terpine〇l) and ruthenium alcohol One of the poly vinyl butyrals. Next, as shown in FIG. 4E, a second drying is performed to remove the organic solvent of the second slurry 230, and the second slurry 23 is formed. Is the second coating 230 A. In this embodiment, since the organic solvent of the second slurry 23 is partially or completely removed by drying, the second slurry 230 is more gelatinized and partially Curing, after drying, the second coating 230A having a thickness of about 2 to 3 micrometers (em) is obtained on the first coating 220A. That is, the first coating 220A and the second coating The 230A series may have the same thickness. Further, after drying the second 10 201115773 slurry 230, another heat treatment may be performed. The first coating 22A and the second coating 230A are used to remove the binder. Specifically, the temperature of the heat treatment can be controlled at about 250 ° C. The low melting point makes the first The coating 22〇a phase is sintered to reduce the internal stress of the bound sintering. Finally, as shown in FIG. 4F, a selenization heat treatment is performed to sinter the first coating 220A and the second coating 23〇a to form a dense And one of the large copper indium gallium selenide thin films 240 (the first coating 22A and the first coating 230A have been sintered into the copper indium gallium germanium film 24, so φ is not shown in the figure) Since the copper-rich powder 221 has a relatively advanced liquid phase with respect to the copper-deficient powder 231, a liquid is used. More specifically, this step was carried out in a selenide furnace at 55 Torr: holding temperature for 3 Torr. Referring to the microstructure diagram shown in FIG. 5, in the present embodiment, the copper-rich powder 22 i has a particle size distribution of 10 to 100 nanometers of the powder of the copper-deficient powder 23 1 which can be a nanometer grade ( Nm).

Therefore, the non-vacuum slurry coating process is used, and the copper indium gallium barrier conversion rate is increased. In addition, by reducing the amount of raw materials to reduce the amount of 201115773, and eliminating the cost of using a vacuum coating machine, the overall output can be increased, thereby significantly reducing production costs. Referring to Figure 6, there is shown the volume shrinkage of the absorbent layer of the present invention and the conventionally produced solar cell of the battery of 5 5 。.匚 Hold the relationship between different temperatures. The figure shows that the solar cell absorbing layer of the present invention having a multilayer structure has no significant change in volume shrinkage as the temperature holding time increases, which can effectively reduce the internal stress of the bound sintering. However, the conventional solar cell absorber layer has a higher volume shrinkage rate as the holding time increases, and as shown in FIG. 6, the conventional solar cell absorber layer has a volume shrinkage ratio of about 〇 at minute. After holding the temperature for 50 minutes, the volume shrinkage rate increased to about 0.10. That is to say, the conventional solar cell absorption layer will change its volume shrinkage significantly due to the holding time (especially between holding temperature and 50 minutes), so it cannot achieve the effect of densification (such as Figure 2). Please refer to FIG. 7 again. This figure is a microscopic cross-section of a copper indium gallium selenide film produced by a method of the present invention after passing through a 55 (TC selenization heat treatment for 30 minutes). Finally, please refer to Fig. 8, which shows that the X-ray diffraction pattern of the absorption layer of the solar cell of the present invention shows that the solar cell absorption layer can obtain a single chalcopyrite after sintering. The invention further discloses a structure of the absorption layer of the solar cell, which is illustrated in section 4F. The structure is composed of two coatings (such as the first coating 220A and the second coating 230A shown in FIG. 4e). Sintering is formed into a dense and grain-rich one copper indium gallium selenide film 240. Preferably, as shown in Fig. 7, the copper indium gallium selenide film 240 can be a single yellow steel ore 12 201115773 phase (chalcopyrite That is, the copper indium gallium magnetic film 240 is a dense solar cell absorbing layer having a large crystal grain, which can increase the conversion rate of the solar cell. In this embodiment, the solar cell substrate 21 can be a glass substrate and formed on the surface There is a metal layer 211, and the material of the metal layer 211 is molybdenum (Mo). In a preferred embodiment, the metal layer 211 can be formed by sputtering and has a thickness of about 1 micrometer (μηι). It is merely a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, although the present invention has been described in the preferred embodiment of the present invention, however, it is not intended to limit the invention. It is still within the technical scope of the present invention to perform any simple Y-multiple, taste equivalence change and modification without departing from the technical scope of the present invention. [Simple description of the drawings] Figs. 1 and 2: $3Fig. 4A to Fig.: is a schematic cross-sectional view of an absorption layer formed by a conventional copper indium gallium selenide slurry.

A microstructural diagram of a conventional copper indium gallium selenide slurry. A block diagram of a method of fabricating a solar cell absorber layer in accordance with an embodiment of the present invention. The cross-sectional view of the element of the method for manufacturing the solar cell of the solar cell of the present invention is a micro-pattern of the copper-free J powder and the copper-deficient powder. According to one embodiment of the present invention, a solar cell diagram of an eight-body embodiment according to an embodiment of the present invention is shown in a method of manufacturing a layer of solar energy, and the manufacturing method of the layer of 201115773 according to an embodiment of the present invention is 55 (TC in A comparison of the changes in volume shrinkage rate produced by different temperature holding times. Fig. 7 is a microscopic cross-sectional view of a copper indium gallium selenide film formed by a method for producing a solar cell absorber layer according to an embodiment of the present invention.

Fig. 8 is a view showing a method for producing a solar cell absorber layer according to an embodiment of the present invention. The solar cell absorber layer formed by sintering at 550 ° C for 30 minutes can obtain a single chalcopyrite X-ray diffraction pattern. [Main component symbol description] Step 1 provides a solar cell substrate. Step 2: Form a first slurry on the solar cell substrate. Step 3 is dried to remove the organic solvent of the first slurry to form a first coating step 4 to form a second slurry. Drying in step 5 on the first coating to remove the organic solvent of the second slurry to form a second coating step 6 heat treating the first coating layer and the second coating layer to remove the binder step 7 performing a selenization heat treatment to sintering A coating and a second coating form a copper indium graft film T tensile stress 110 slope substrate 14 〇 CIG S absorption layer 141 aperture 14 201115773 210 solar cell substrate 211 220 first slurry 220A first coating 221 230 Two slurry 230A second coating 231 240 copper indium gallium selenide thin film metal layer copper-rich powder copper deficiency powder

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Claims (1)

201115773 VII. Patent application scope: 1. A method for manufacturing an absorption layer of a solar cell, comprising: providing a solar cell substrate; forming a first slurry on the female solar cell substrate, the first material system comprising copper rich Powder, right-handed, 々 organic > gluten and dispersant, chemical formula of rich powder ^ t flying system is cUyl (InxGai x) (SeS) 2 side CUe, where yl > 1, 〇. eu〇8 and proceed Drying once to remove the organic solvent of the first slurry, so that the first slurry is formed into a first coating; after drying the first slurry, the second slurry is formed in the second slurry. On the first coating, the second slurry comprises a copper-deficient powder, an organic solvent, and a copper-deficient powder, which is Cuy2(InxGai.x)(ses)2, wherein π〆, n 八头肀 y2< 1 and 0.4$0.8; performing a second drying to remove the organic solvent of the first slurry, thereby forming the second slurry into a second coating; and performing a thermal treatment, To burn it, now. The first coating layer and the second coating layer are further formed into a dense and crystalline, copper-indium gallium selenide film, which is the first to be used in the first coating. The melting point 'low stagnation's liquid phase' reduces the internal stress of the bound sintering by liquid phase sintering. According to the first paragraph of the patent application, the method of the method is too "the method of making the battery absorption layer, wherein the organic solvent,, „ 你, from toluene, chloroform methylformamidine dimethyl sulphide ( Dime (N, N-Dimethylf〇rmamide) 16 2 201115773 8111! '〇乂丨46) One of the pyridines. 3. The method for producing a solar cell absorber layer according to claim 1 or 2, wherein the dispersant is selected from the group consisting of oleylamine, alkylsen〇i, and alkylthiol. ), one of aromatic selenol (ar〇matic seien〇l) and aromatic sulfur (aromatic thiol). 4. The method for manufacturing a solar cell absorbing layer according to claim 1, wherein the first slurry and the second slurry respectively comprise a binder for adjusting the viscosity and film formation of the slurry. Sex. 5. The method for producing a solar cell absorbing layer according to claim 4, wherein the binder is selected from the group consisting of ethyl cellulose (dihydr〇terpineol) and polyvinyl butyral (p〇iyvinyi butyral). one of them. 6. The method of manufacturing a solar cell absorbing layer according to claim 5 of the patent application scope, after the drying of the second slurry and the step of heat treatment in the selenization heat treatment, wherein the step of: heat treating the first coating layer and the first A second coating to remove the binder. 7. The method of producing a solar cell absorbing layer according to claim 1, wherein the first slurry and the second slurry are formed in a printing manner. 8. The method for preparing a solar cell absorbing layer according to the scope of claim 1 wherein the steel-rich powder and the copper-deficient powder are nano-sized powders, and the particle size is estimated to be 100 nanometers. 9. According to the method of manufacturing a solar cell absorbing layer of the patent application No. 1, the first coating layer and the second coating layer have the same thickness. 10. The method of producing a solar cell absorbing layer according to claim 1, wherein the solar cell substrate is a glass substrate and a metal layer is formed on the surface, and the material of the metal layer is molybdenum. A structure of an absorption layer of a solar cell, which is formed by the manufacturing method of the first aspect of the patent application, which is formed by sintering two coatings to form a film of copper indium gallium nitride which is dense and has a large crystal grain. 12. The structure of a solar cell absorbing layer according to the scope of the patent application of the invention, wherein the solar cell substrate is a glass substrate, and a metal layer is formed on the surface, and the material of the metal layer is turned over. U. According to the structure of the solar cell absorption layer of claim 11 of the patent application, wherein the copper indium gallium selenide film is a single chalcopyrite phase. 18