KR101289246B1 - Preparation method for i b iii b vi b compound solar cell precursor via successive applications of one-bath and multi-bath electrodepositions - Google Patents

Abstract

PURPOSE: A manufacturing method of I B III B VI B group thin film solar cell precursor which applies a single electrolyzer electrodeposition method and multiple electrolyzer electrodeposition method at the same time is provided to improve performance by amending a physical property of an electrodeposition thin film. CONSTITUTION: A prepared working electrode is electrodeposited. A thin film of a close-packed structure is formed. A component element is spread equally in the thin film. A value which is deviated from the component element formation ratio is corrected. The multiple electrolyzer electrodeposition method is used for correction.

Description

Preparation method for IBIIIBVIB compound solar cell precursor via successive applications of one-bath and multi-bath electrodepositions

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film solar cell precursor, and more particularly, to compound semiconductor thin films such as IIIBVB-based semiconductor solar cells such as GaAs, IIBVIB-based semiconductor solar cells such as CdTe, and IBIIIBVIB-based semiconductor solar cells such as CIS. The present invention relates to a method of manufacturing a precursor of an IBIIIBVIB-based thin film solar cell using a single electrolytic cell electrodeposition method and a multiple electrolytic cell electrodeposition method simultaneously.

The general structure of the IB IIIB VIB-based thin film solar cell is to sputter a molybdenum layer having a thickness of about 1 micron on a lower substrate such as glass, stainless steel, titanium, aluminum, or polyimide, and place a p-type IBIIIBVIB semiconductor light absorbing layer thereon. And a buffer layer such as CdS, Zn (O, S, OH), ZnMgO, In (O, S, OH), or In ₂ S ₃ , which are n-type semiconductors, is placed thereon and an i-ZnO high resistance buffer layer thereon. After raising, the n-ZnO transparent electrode layer, which is an n-type semiconductor, is placed thereon, and finally, an antireflection layer and a surface electrode are formed (see FIG. 1).

Here, there are four methods of forming an absorbing layer using the IBIIIBVIB-based p-type semiconductor, which plays a decisive role in the photovoltaic conversion efficiency, that is, the power generation performance of the IBIIIBVIB-based thin film solar cell, such as the co-evaporation method, the sputtering method, the electrodeposition method, and the ink method. Known as

The present invention relates to a method of manufacturing an IBIIIBVIB-based p-type semiconductor thin film using the electrodeposition method among these. When the precursor of the IBIIIBVIB-based absorbing layer was prepared by electrodeposition, the group IB (Cu, Ag, and Au), IIIB (B, Al, Ga, In and Tl), and VIB (O, S, Se) of the periodic table , Te, and Po) have a one-bath electrodeposition for simultaneously dissolving at least one element from each group in one electrolyzer and simultaneously electrodeposition, and having a plurality of electrolyzers, At least one of the elements of Group IB (Cu, Ag, and Au), Group IIIB (B, Al, Ga, In, and Tl) and Group VIB (O, S, Se, Te, and Po) on the periodic table The multi-bath electrodeposition method which contains the above element and continuously electrodeposits in each electrolytic cell to form a multilayered structure is common.

The single electrolytic cell electrodeposition method is easy to install and process because the electrodeposition is performed by one electrodeposition process in one electrolyzer, and the thin film obtained because the film formation is performed by mixing each component at the same time is the component elements are uniformly mixed. Thus, a more uniform and dense crystal structure can be obtained through crystallization by heat treatment, which is the next process. However, it is difficult to find the conditions for dissolving all component ions at the same time, and the standard reduction potential of each component ions is greatly different, and this may also change the electrodeposition environment such as pH and temperature when electrodeposited in the form of compounds among the components. In addition, there is a problem that the reduction potential is different, and the electrodeposition rate of each component is also different, so it is very difficult to select a reduction potential for electrodeposition, and even if the optimum reduction potential and solution composition are found, It is known that it is relatively difficult to obtain a thin film with reproducible element composition ratio because it is very sensitive to concentration error or concentration change and electrodeposition environment. [Solar Energy Materials & Solar Cells 80 483-490 (2003).]

On the other hand, the multi-electrolyzer electrodeposition method dissolves the component elements separately in a plurality of electrolytic cells, such as two, three, four, etc., to form a multi-layer structure by continuously electrodepositing a thin film layer having different components in each electrolytic cell As a result, the solution composition becomes relatively simple for each electrolytic cell, and thus the optimum electrodeposition conditions for electrodeposition of each thin film layer can be found relatively easily, so that it is relatively easy to control the element composition ratio of the entire multilayer structure. The electrolytic bath is required, which makes the facility complicated and the process complicated by the various stages of electrodeposition process. The obtained thin film is made of multi-layered structure. It has been known to be relatively disadvantageous in obtaining a compound crystal structure. . [US Patent # 4,581,108.]

On the other hand, a representative IBIIIBVIB semiconductor is a CIS semiconductor composed of copper, indium (or indium and gallium), and selenium (or selenium and sulfur). The most important ratio between elements in the composition ratio is copper: indium (or indium + gallium). When the ratio of copper is larger based on the ratio of 1: 1, p-type Cu _2-x Se having high conductivity is also formed in the resulting CIS-based thin film, and thus it cannot be used as a solar cell. suitable physical properties when the case the ratio is only slightly smaller is used as a CIS-based semiconductor crystal blanks of copper atoms in the lattice (V _Cu) is to high the vacancy acts as an acceptor springing the nature of the p-type semiconductor shown CIS based thin film solar absorbing layer However, as the ratio of copper gradually decreases, V _Cu increases, and indium atoms (or gallium atoms) enter some of the increased V _Cus , which are substituted sites (In _Cu or In _Ga ). As the donor acts as a donor, the overall physical properties change from a p-type semiconductor to an n-type semiconductor, and thus it is difficult to use as a solar cell because it does not function properly as an absorbing layer.

Therefore, in CIS-based thin-film solar cells, the electrical characteristics are highly dependent on the component ratio, and the optimum ratio of copper to indium (or indium + gallium) to selenium (or selenium and sulfur) is generally 1: 1 (or 0.7 + 0.3): 2, and more specifically, a slight lack of copper ratio, i.e. copper: indium (or indium + gallium): selenium (or selenium and sulfur) = 1-y: 1 + y: 2 (y = 0.05 to 0.11) is suitable.

In addition, in mass production of CIS solar cells, a technique for economically and effectively controlling the component ratio of the CIS absorber layer is very important.

In the above case, in order to obtain uniform CIS crystals with uniform mixing between atoms in the electrodeposition method, it is advantageous to use the single electrolytic cell electrodeposition method, but it is difficult to achieve the optimum component ratio because many conditions required for electrodeposition must be matched at once. . Therefore, there is a need for an additional method that can correct the component composition ratio.

On the other hand, Bhattacharya et al., In US Patent # 5,871,630 and Thin Solid Films 361, 396 (2000), form a CIGS light absorbing layer by a single electrolytic cell electrodeposition method, and copper and selenium or indium and selenium to PVD (Physical Vapor Deposition) to match the composition ratio. The method was introduced by the post-treatment process, which recorded up to 15.4% optical conversion efficiency. However, this method uses the PVD method, which requires a high vacuum environment in addition to the electrodeposition method, and therefore requires economical equipment such as high vacuum equipment, high purity materials, and cannot use more than 95%. This represents a problem of losing the advantages of electrodeposition.

Therefore, there is a need to develop a method for maintaining the economic advantages obtained by the electrodeposition method when the composition ratio between the elements of the CIS-based thin film solar cell precursor obtained in the single electrolytic cell electrodeposition method to the optimum conditions.

The present invention thus solves the problems of the prior art as described above, and maintains the economic advantages obtained in the electrodeposition method in the precursor of the IBIIIBVIB-based compound thin film solar cell electrodeposition method, applying only the electrodeposition method component The purpose of the present invention is to provide a method for manufacturing an IBIIIBVIB thin film solar cell precursor which simultaneously adopts a single electrolytic cell electrodeposition method and a multiple electrolytic cell electrodeposition method, which establishes a method for controlling the element composition ratio and optimizes and corrects the element composition ratio accordingly. have.

The present invention is a method for producing an IBIIIBVIB compound semiconductor thin film solar cell precursor by electrodeposition in order to achieve the object of the present invention as described above, the component elements are uniformly distributed on the prepared working electrode, a thin film having a dense structure A single electrolytic cell electrodeposition method for forming a film, and a multiple electrolytic cell electrodeposition method are used to correct the deviation from the optimum component composition ratio when forming an IBIIIBVIB compound semiconductor thin film using the precursor thin film obtained from the single electrolytic cell electrodeposition method. It provides a method of manufacturing a solar cell precursor.

The IBIIIBVIB-based semiconductors include Group IB including Cu, Ag, and Au on the periodic table; It is composed of one or more elements selected from group IIIB including B, Al, Ga, In and Tl, and group VIB including O, S, Se, Te and Po. It is desirable to correct the component composition ratio by performing the multi-electrolyzer electrodeposition. The reason is that the composition of the precursor thin film obtained by the single-electrolyzer electrodeposition method is often copper-rich, and such copper-rich This is because a precursor thin film having a phosphorus composition causes impurity phases such as Cu _2-x Se to be formed in the crystallization of the IBIIIBVIB-based compound semiconductor by the subsequent selenization heat treatment, making it unsuitable for use as a solar cell.

In addition, the element composition of the IBIIIBVIB-based compound semiconductor is Cu-In-S, Cu-In-Se, Cu-In-Se-S, Cu-Ga-S, Cu-Ga-Se, Cu-In-Ga-S, It is preferable that it is one of elemental compositions, such as Cu-In-Ga-Se and Cu-In-Ga-Se-S.

In addition, the single electrolytic cell electrodeposition is to form a thin film having a dense structure in which the element elements are uniformly distributed, and in the single electrolytic cell, the components of IB, IIIB, and VI are electrodeposited and then electrodeposited to form Mo / ⅠBIIIBVIB. Structure was formed, followed by electrodeposition in a single or plural electrolysers containing group IB elements and group IIIB elements by multi-electrolyzer electrodeposition, followed by Mo / ⅠBIIIBVIB / ⅠB / IIIB structures or Mo / ⅠBIIIBVIB / ⅠB / A precursor of IIIB / IIIB 'structure is formed.

In addition, the working electrode in the single electrolytic cell electrodeposition process is using Mo as the working electrode, the solution composition of the electrolytic cell is preferably composed of CuCl ₂ , InCl ₃ , GaCl ₃ , H ₂ SeO ₃ and LiCl.

In addition, the electrolyzer in the multi-electrolyzer electrodeposition process is preferably composed of a copper electrolyzer and an indium electrolyzer (or indium and gallium electrolyzer) or a copper electrolyzer, an indium electrolyzer and a gallium electrolyzer, wherein the solution composition of the copper electrolyzer is CuSO ₄ , Na ₂ SO ₄ and H ₂ SO ₄ , the solution composition of the indium electrolytic cell comprises InCl ₃ and NaCl (or the solution composition of the indium and gallium electrolytic cell InCl ₃ , GaCl ₃ and NaCl), the solution composition of the gallium electrolytic cell is GaCl ₃ and It is preferably composed of NaCl.

According to the present invention as described above, while maintaining the advantages of the electrodeposition method can be corrected by performing a multi-electrolyzer process of the electrodeposited thin film obtained through a single electrolyzer, the optimum component element composition ratio to make a high performance thin film solar cell precursor Can be obtained. In addition, manufacturing a solar cell device using the precursor through the method of the present invention can exhibit a high conversion efficiency, it is possible to provide a high performance IBIIIBVIB compound semiconductor thin film solar cell.

1 is a general structural diagram of an IBIIIBVIB-based thin film solar cell.
Figure 2 is a graph of the results using the solar simulation of CIGS cell device performance according to an embodiment of the present invention.
Figure 3 is a graph of the results using the solar cell CIGS cell device performance according to another embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. The following examples are intended to explain the present invention to those skilled in the art, but not to limit the present invention.

In the present invention, in forming the precursor of the IBIIIBVIB-based semiconductor thin film solar cell, the components are uniformly distributed to form a high density thin film, and at this time, a method for easily adjusting the composition ratio between the required components is provided. It provides a way to take advantage of the electrodeposition method from an economical point of view, such as no need for expensive vacuum equipment, high purity materials, and 95% or more material usage.

To this end, in the present invention, the formation of a thin film of a dense structure in which the component elements are uniformly distributed is performed through a single electrolytic cell electrodeposition method, and this single electrolytic cell electrodeposition method alone makes it difficult to match the optimum composition ratio between the component elements. In order to correct the deviation from the composition ratio, the multiple electrolytic cell electrodeposition method is applied.

In this case, the elements of group VIB of the main components of the IBIIIBVIB compound semiconductor thin film solar cell can be corrected in the selenization process accompanied by heat treatment after the preparation of the precursor of the IBIIIBVIB compound semiconductor thin film solar cell. Therefore, the optimum composition ratio between the elements can be adjusted by correcting only the elements of the remaining Group IB and Group IIIB elements. Therefore, the multielectrolyzer electrodeposition method uses an electrolytic cell containing Group IB elements and an electrolytic cell containing Group IIIB elements. Need.

As a result, the present invention is characterized by the continuous application of the single electrolytic cell electrodeposition method and the multiple electrolytic cell electrodeposition method, and this series of electrodeposition methods are referred to as hybrid-electrodeposition.

In the single electrolytic cell electrodeposition process, each of the constituent elements of the IBIIIBVIB compound semiconductor thin film solar cell absorption layer precursor is dissolved in an aqueous solution and ionized to prepare an aqueous electrolyte solution. In this case, additives such as a supporting electrolyte, a brightening agent, a corrosion inhibitor, a dispersing agent, a complex forming agent, and a pH buffering agent may be added to improve the solution properties, and the concentration of each component is the electrodeposition rate, electrodeposition amount (deposition thickness), and the resulting thin film. Depends on the composition ratio of the component elements. The obtained aqueous electrolyte solution is placed in an electrolytic cell and formed by a constant current method using molybdenum as a working electrode and applying a constant current. Here, the electrodeposition speed varies depending on the current density, and the physical properties of the electrodeposited thin film obtained at the same time vary.

A multi-electrolyzer electrodeposition method uses a plurality of electrolyzers, each of which is an electrolyzer comprising an element of group IB and an electrolyzer comprising an element of group IIIB. In order to improve the solution characteristics of each electrolyzer, a supporting electrolyte, a polishing agent, Additives such as corrosion inhibitors, dispersants, complexing agents, pH buffers and the like can be added. Since each electrolytic cell is easy to control the electrodeposition environment because its solution composition is relatively simple, the solution composition of the electrolytic cell can be suitably selected to provide an optimal component composition ratio for the precursor of the thin film solar cell. It becomes adjustable.

[Example 1]

A back electrode was manufactured by sputtering Mo of l 탆 on 3 mm thick soda lime glass (SLG). The surface resistance of the back electrode was about 0.24 Ω / cm 2. For electrodeposition, the rear electrode was cut into 25 ㅧ 70 cm 2 and used as a working electrode.

The electrodeposition process was carried out by constant current method using Fisher Scientific's FB300Q power supply. The electrode was a two-electrode system of Mo / SLG working electrode and platinum relative electrode.

First, the solution composition of the electrolytic cell for the single electrolytic cell electrodeposition method consisted of 3 mM CuCl ₂ , 4.5 mM InCl ₃ , 7 mM GaCl ₃ , 5.1 mM H ₂ SeO ₃ , and 0.32 M LiCl.

Electrodeposition conditions consisted of a current density of 0.5 mA / cm 2 and an electrodeposition time of 20 minutes at an aqueous solution temperature of 25 ° C.

The thin film obtained by the single electrolytic cell electrodeposition method (CIGS) was used as the working electrode of the following multielectrolyte electrodeposition method after washing with ultrapure water and drying with nitrogen.

Next, the multi-electrolyzer electrodeposition method consisted of two electrolyzers, a copper electrolyzer and an indium electrolyzer. Using a two-electrode system in which a thin film obtained by a single electrolytic cell electrodeposition method was placed in a copper electrolytic cell as a working electrode and platinum as a counter electrode, electrodeposited for 2 minutes at a current density of 5.5 mA / cm 2 at an aqueous solution temperature of 25 ° C., followed by cleaning with ultrapure water and nitrogen After drying in an indium electrolytic cell, using a two-electrode system as a working electrode and platinum as a counter electrode, electrodeposition was carried out for 5 minutes at a current density of 5.5 mA / cm 2 at an aqueous solution temperature of 25 ° C, washed with ultrapure water, and dried with nitrogen. Obtained.

The solution composition of the copper electrolyzer was 0.1 M CuSO ₄ , 0.1 M Na ₂ SO ₄ and 0.1 MH ₂ SO ₄ , and the solution composition of the indium electrolyzer was 0.2 M InCl ₃ and 0.1 M NaCl.

The obtained sample was reacted with selenium vapor for 45 minutes in a 500 ℃ selenium vacuum deposition equipment to obtain a structure of SLG / Mo / CIGS through the process of interdiffusion and crystallization (Crystallization). The component ratio of the obtained CIGS absorption layer was Cu: 22.1 atom%, In: 28.7 atom%, Ga: 0.33 atom%, and Se: 48.9 atom%.

Next, in order to form a CdS buffer layer, the CdS layer was chemically grown for 15 minutes in a 500 mL basic aqueous solution containing 2 mM CdCl ₂ , 75 mM SC (NH ₂ ) ₂ , and 60 mL of NH ₄ OH at a temperature of 65 ° C.

Next, using a ZnO and ZnO: Al (Al ₂ O ₃ 2.wt%) target, respectively, 100 nm i-ZnO layer and 1 μm n-ZnO layer were formed by sputtering, and finally, the screen was screened on the surface. Metal grids were formed by printing to prepare CIGS cell devices.

The performance of the manufactured CIGS cell device was confirmed by using a solar simulator showed a conversion efficiency of 5.97% in an area of 0.430 cm 2 (see Fig. 2).

[Example 2]

A back electrode was prepared by sputtering 1 μm thick Mo on 3 mm thick soda lime glass (SLG). The surface resistance of the back electrode was about 0.24 Ω / cm 2. For electrodeposition, the rear electrode was cut into 25 ㅧ 70 cm 2 and used as a working electrode.

The electrodeposition process was carried out by constant current method using Fisher Scientific's FB300Q power supply. The electrode was a two-electrode system of Mo / SLG working electrode and platinum relative electrode.

First, the solution composition of the electrolytic cell for the single electrolytic cell electrodeposition method was composed of 3mM CuCl ₂ , 7 mM GaCl ₃ , 5.1 mM H ₂ SeO ₃ , and 0.32 M LiCl.

Electrodeposition conditions consisted of a current density of 0.5m A / cm 2 and an electrodeposition time of 20 minutes at an aqueous solution temperature of 25 ° C.

The thin film (CGS) obtained by the single electrolytic cell electrodeposition method was used as the working electrode of the following multielectrolyte electrodeposition method after washing with ultrapure water and drying with nitrogen.

Next, the multi-electrolyzer electrodeposition method consisted of two electrolyzers, a copper electrolyzer and an indium electrolyzer. The sample obtained by the electrolytic cell electrodeposition method was placed in a copper electrolytic bath as a working electrode and platinum was used as a counter electrode. Electrode electrodeposition was carried out for 2 minutes at a current density of 5.5 mA / cm 2 at an aqueous solution temperature of 25 ° C, followed by cleaning with ultrapure water. After drying in an indium electrolytic cell, using a two-electrode system as a working electrode and platinum as a counter electrode, electrodeposition was carried out for 5 minutes at a current density of 5.5 mA / cm 2 at an aqueous solution temperature of 25 ° C, washed with ultrapure water, and dried with nitrogen. Obtained.

The solution composition of the copper electrolyzer was 0.1 M CuSO ₄ , 0.1 M Na ₂ SO ₄ and 0.1 MH ₂ SO ₄ , and the solution composition of the indium electrolyzer was 0.2 M InCl ₃ and 0.1 M NaCl.

The obtained sample was reacted with selenium vapor for 45 minutes in 500 ℃ selenium vacuum deposition equipment to obtain a structure of SLG / Mo / CIGS through the interdiffusion and crystallization process. The component ratio of the obtained CIGS absorption layer was Cu: 20 atom%, In: 29 atom%, Ga: 0.35 atom%, and Se: 49.9 atom%.

Next, in order to form a CdS buffer layer, the CdS layer was chemically grown for 15 minutes in a 500 mL basic aqueous solution containing 2 mM CdCl ₂ , 75 mM SC (NH ₂ ) ₂ , and 60 mL of NH ₄ OH at a temperature of 65 ° C.

Next, using a ZnO and ZnO: Al (Al ₂ O ₃ 2.wt%) target, respectively, 100 nm i-ZnO layer and 1 μm n-ZnO layer were formed by sputtering, and finally, the screen was screened on the surface. Metal grids were formed by printing to prepare CIGS cell devices.

The performance of the manufactured CIGS cell device was 7.79% conversion efficiency in the area of 0.430 cm 2 as confirmed by the solar simulator (see Fig. 3).

Claims (10)

A method for producing an IBIIIBVIB-based semiconductor thin film solar cell precursor by electrodeposition, comprising: a single electrolytic cell electrodeposition method for forming a densely packed thin film with uniformly distributed elemental elements for electrodeposition to a prepared working electrode, and a component element of an IBIIIBVIB-based semiconductor precursor A method of manufacturing a solar cell precursor characterized by using a multiple electrolytic cell electrodeposition method for correcting a value deviating from the composition ratio. The semiconductor of claim 1, wherein the IBIIIBVIB-based semiconductor comprises: a group IB including Cu, Ag, and Au on a periodic table; A method for manufacturing a solar cell precursor, comprising elements selected from group IIIB including B, Al, Ga, In, and Tl, and group VIB including O, S, Se, Te, and Po. The method of manufacturing a solar cell precursor according to claim 1, wherein the electrodeposition is carried out after the single electrolytic cell electrodeposition. The method of claim 1, wherein the semiconductor is Cu-In-S, Cu-In-Se, Cu-In-Se-S, Cu-Ga-S, Cu-Ga-Se, Cu-In-Ga-S, Cu -In-Ga-Se and Cu-In-Ga-Se-S manufacturing method of a solar cell precursor, characterized in that one of the composition. The method of claim 1, wherein the multi-electrolyzer electrodeposition uses an electrolytic cell containing a group IB element and an electrolytic cell containing a group IIIB element. The method of claim 1, wherein the working electrode in the single electrolytic cell electrodeposition process using Mo as the working electrode, the solution composition of the electrolytic cell is characterized in that consisting of CuCl ₂ , InCl ₃ , GaCl ₃ , H ₂ SeO ₃ and LiCl Method for manufacturing a solar cell precursor. The method of claim 5, wherein the electrolytic cell in the multi-electrolyzer electrodeposition process is a copper electrolytic cell and an indium electrolytic cell, or a copper electrolytic cell, an indium electrolytic cell and a gallium electrolytic cell. The solution composition of claim 7, wherein the solution composition of the copper electrolyzer comprises CuSO ₄ , Na ₂ SO _4, and H ₂ SO ₄ , wherein the solution composition of the indium electrolyzer is InCl ₃ and NaCl, and the solution composition of the indium and gallium electrolyzer is InCl _3. A method of manufacturing a solar cell precursor comprising GaCl ₃ and NaCl, and the solution composition of the gallium electrolyzer consists of GaCl ₃ and NaCl. The method of manufacturing a solar cell precursor according to claim 6, wherein a Mo / CIGS layer including four components of Cu, In, Ga, and Se is formed after the single electrolytic cell electrodeposition process. 8. The method of claim 7, wherein the Mo / CIGS / Cu / In or Mo / CIGS / Cu / (In, Ga) or Mo / CIGS / Cu / In / Ga or Mo / CIGS / Cu / Ga / Method of manufacturing a solar cell precursor, characterized in that the precursor of In structure is formed.

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