Precursor solution for inorganic compound thin-film solar cell, preparation method and application thereof

Abstract

The invention discloses a precursor solution for an inorganic compound thin-film solar cell and a preparation method and application thereof, and belongs to the field of thin-film solar cells, the precursor solution for the inorganic compound thin-film solar cell comprises the following raw materials: a metal precursor compound, a sulfur-containing ligand and a solvent; metals in the metal precursor compound comprise indium, gallium and copper or zinc, tin and copper; the metal precursor compound further comprises one or more of sulfate radical, acetate radical and nitrate radical; according to the precursor solution, complex chemical reaction in the film forming process is avoided, an absorption layer film which is large in grain, free of impurities and smooth in surface is formed, and the photoelectric conversion efficiency of an inorganic compound film solar cell is improved.

Description

Technical Field

[0001] The invention belongs to the field of thin-film solar cells, and in particular relates to a precursor solution for inorganic compound thin-film solar cells, a preparation method and an application thereof. Background Art

[0002] Solar energy is an inexhaustible energy source. The development of solar energy, a green and sustainable new energy source, can not only meet the energy needs of industrial production and daily life, but also protect the ecological environment. The photovoltaic industry, as the fastest-growing and most dynamic research field in recent years in the field of solar light-to-electricity, is a very promising direction. So far, many types of solar cells have been developed and commercialized. Among them, crystalline silicon solar cells have occupied more than 90% of the commercial photovoltaic market. However, the manufacture of crystalline silicon cells requires very thick wafers and high temperature / vacuum processes, which are costly and limit their application in flexible and lightweight battery devices. The development of thin-film photovoltaic technology is crucial to the expansion of the photovoltaic market. Inorganic compound thin films are a research hotspot in the field of thin-film photovoltaics due to their environmental friendliness and high stability.

[0003] The preparation process of inorganic compound thin films can generally be divided into two categories: vacuum method and non-vacuum method. The thin films prepared by vacuum method are of high quality, but expensive high vacuum equipment is required, the film preparation process has high energy consumption and low material utilization rate. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a precursor solution for an inorganic compound thin-film solar cell, a preparation method and application thereof.

[0005] A precursor solution for inorganic compound thin-film solar cells comprises the following raw materials: a metal precursor compound, a sulfur-containing ligand and a solvent; the metal in the metal precursor compound comprises indium, gallium and copper or zinc, tin and copper; the metal precursor compound further comprises one or more of sulfate, acetate and nitrate.

[0006] Preferably, the molar ratio of copper, indium, gallium and sulfur in the sulfur-containing ligand is 1:0.7-1:0-0.3:5-6.

[0007] Preferably, the molar ratio of the copper, zinc, tin and sulfur in the sulfur-containing ligand is 1:0.6-1:0.6-1:3-4.

[0008] Preferably, the sulfur-containing ligand comprises thiourea.

[0009] Preferably, the solvent includes N,N-dimethylformamide and dimethyl sulfoxide.

[0010] A method for preparing a precursor solution for an inorganic compound thin-film solar cell comprises adding a solvent to a sulfur-containing ligand, stirring, then adding a metal precursor compound, and stirring until the compound is dissolved to obtain a precursor solution.

[0011] Application of the above-mentioned precursor solution or the precursor solution prepared by the above-mentioned preparation method in the production of solar cells.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention provides a precursor solution for preparing an inorganic compound thin film solar cell. By replacing a metal precursor compound containing acetate, sulfate or nitrate or adding an oxygen-containing acid, acetate, sulfate or nitrate is introduced, and the metal ions in the solution are pre-associated together by utilizing the strong coordination ability and hydrogen bonding of oxygen atoms to form a stable and uniform network macromolecular structure. The method avoids the aggregation of metal elements, thereby avoiding the complex chemical reactions in the film forming process, forming an absorption layer film with large grains, no impurities and a smooth surface, and improving the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 The SEM morphology images of the copper indium gallium selenide thin films of Examples 1-5 of the present invention and Comparative Example 1 are shown.

[0016] Figure 2 JV curves of the copper indium gallium selenide solar cells of Examples 1-5 of the present invention and Comparative Example 1.

[0017] Figure 3 JV curves of the copper-zinc-tin-sulfur-selenium solar cells of Examples 6-8 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1

[0020] Take 6 ml of N, N-dimethylformamide as solvent, first add 0.033 mol of thiourea, continue stirring until the solution is clear and transparent, then add 0.0042 mol of InCl3·4H2O and 0.0018 mol of CaCl3, continue stirring until the solution is clear and transparent, and finally add 0.006 mol of Cu(CH3COO)2·H2O (the molar ratio of each element in the solution is Cu:In:Ga:S=1:0.7:0.3:5.5), continue stirring until the solution turns light yellow and a yellow precipitate is generated. After filtering the prepared solution with a 0.8 micron filter, use a scraping method to apply the solution to a cleaned molybdenum-coated sodium-lime glass substrate, then place the sample on a hot stage at 340°C for annealing for 1 min and remove it. After the sample cools, repeat the above scraping-annealing process 5 times to obtain a precursor film. Then, the precursor film was placed in a graphite box with a cover and 0.35 g of selenium particles were added, and then placed in a tube furnace. Under an argon protection environment, the precursor film was annealed at 590°C for 18 min (selenization) to obtain a copper indium gallium selenide absorption layer film. The copper indium gallium selenide absorption layer film obtained in each embodiment and comparative example was analyzed by scanning electron microscopy (SEM). A CdS buffer layer, a ZnO\ITO window layer and a Ni / Al metal electrode were sequentially deposited on the obtained copper indium gallium selenide absorption layer film to prepare a solar cell device. The prepared battery was placed on the platform of the solar cell, and the probes of the test platform were respectively inserted into the positive and negative electrodes of the battery, and then the wires of the probes were connected to the Keithley 2400 data source table. The matching test software on the computer was opened, and the irradiance generated by the AAA solar simulator (CROWNTECH. Inc.) was 100 mW / cm at a temperature of 25°C. 2 Under AM 1.5 white light conditions, the current and voltage generated by the battery were measured and recorded using a Keithley 2400 data source meter to obtain the battery's open circuit voltage (V OC ), short-circuit current density (J SC ), fill factor (FF) and photoelectric conversion efficiency (PCE).

[0021] Example 2

[0022] Example 1 was repeated with the same steps, except that 0.03 mol of thiourea, 0.0045 mol of InCl3·4H2O, and 0.0015 mol of GaCl3 were added (the molar ratio of each element in the solution was Cu:In:Ga:S=1:0.75:0.25:5).

[0023] Example 3

[0024] Example 1 was repeated with the same steps, except that 0.036 mol of thiourea and 0.0042 mol of InCl3·4H2O were added, and no GaCl3 was added (the molar ratio of each element in the solution was Cu:In:Ga:S=1:1:0:6).

[0025] Example 4

[0026] Example 1 was repeated with the same steps, except that the added Cu(CH3COO)2·H2O was replaced by CuSO4.

[0027] Example 5

[0028] Example 1 was repeated with the same steps, except that the added Cu(CH3COO)2·H2O was changed to CuCl, and 0.012 mol acetic acid was added to the solution.

[0029] Comparative Example 1

[0030] Example 1 was repeated with the same steps, except that the added Cu((CH3COO))2·H2O was replaced by CuCl.

[0031] Thin film morphology analysis:

[0032] Figure 1 The surface SEM images of the copper indium gallium selenide absorption layer film are compared. It can be seen that the grain size of the film of Examples 1-5 is significantly larger than that of Comparative Example 1, and the grain size is more uniform, the film surface is smoother, and the coverage is full without holes and impurity particles.

[0033] Battery device performance analysis:

[0034] Figure 2 is the JV curve of the copper indium gallium selenide thin film solar cell, and the corresponding device performance parameters are listed in Table 1.

[0035] Table 1 Photovoltaic performance parameters of CIGS solar cells

[0036]

[0037] It can be concluded from Table 1 that the efficiency of the solar cell devices of Examples 1-5 are 15.95%, 15.63%, 15.73% and 15.09 respectively, which is significantly better than the 11.97% efficiency of Comparative Example 1. The above results show that the precursor solution introducing oxygen-containing acid radicals (acetate, sulfate, etc.) can prepare an absorption layer film with larger grain size, smoother surface and no impurities, thereby improving the photoelectric conversion efficiency of the battery. The reason is that the oxygen atoms of the oxygen-containing acid have strong coordination ability and hydrogen bonding, which can pre-associate the metal ions in the solution together to form a stable and uniform network macromolecular structure, reduce the aggregation and freeness of metal ions, thereby avoiding the complex chemical reaction of the film forming process, reducing impurities in the film, improving the phase purity, forming a large grain, impurity-free, smooth surface absorption layer film, thereby improving the photoelectric conversion efficiency of the solar cell.

[0038] Example 6

[0039] Take 4 ml of dimethyl sulfoxide, add 0.0184 mol of thiourea, stir quickly until the thiourea is completely dissolved, then add 0.006 mol of CuCl, as solution 1. Take another 4 ml of dimethyl sulfoxide and mix it with 0.0036 mol of SnCl4, stir quickly until it is clear and transparent, then add 0.0036 mol of Zn(CH3COO)2 (the molar ratio of Cu:Sn:Zn:S in the solution is 1:0.6:0.6:4), stir until the solution is clear and transparent, as solution 2. Finally, mix solution 1 and solution 2 and stir evenly to obtain a light yellow precursor solution. The solution was filtered with a 0.8 micron filter, and then dripped onto a cleaned molybdenum-coated sodium-lime glass substrate. A wet film of the solution was prepared by spin coating. The spin coating speed was 2000 r / min and the spin coating duration was 30 s. After the spin coating was completed, the wet film was immediately transferred to a heating table at 340°C for annealing for 1.5 minutes. The above spin coating-annealing process was repeated 7 times to obtain a precursor film. Subsequently, the precursor film was placed in a graphite box with a cover and 0.5 g of selenium particles were added. It was placed in a tubular furnace and annealed at 540°C for 20 minutes (selenization) under argon protection to obtain a copper-zinc-tin-sulfur-selenium absorption layer film. CdS buffer layer, ZnO / ITO window layer and Ni / Al metal electrode were sequentially deposited on the obtained copper-zinc-tin-sulfur-selenium absorption layer film to prepare a solar cell device. At a light intensity of 100 mW / cm 2 The current-voltage curve of the battery was measured under AM 1.5 white light conditions to obtain the open circuit voltage (V OC ), short-circuit current density (J SC ), fill factor (FF) and photoelectric conversion efficiency (PCE).

[0040] Example 7

[0041] Example 6 was repeated with the same steps, except that 0.021 mol of thiourea, 0.0039 mol of SnCl4, and 0.0036 mol of Zn(CH3COO)2 were added (the molar ratio of Cu:Sn:Zn:S in the solution was 1:0.65:0.65:3.5).

[0042] Example 8

[0043] Example 6 was repeated with the same steps. The difference was that the added thiourea was 0.024 mol, SnCl4 was 0.0042 mol, and Zn(CH3COO)2 was 0.0042 mol (the molar ratio of Cu:Sn:Zn:S in the solution was 1:0.7:0.7:4).

[0044] Example 3 was repeated with the same steps, except that the added Zn(CH3COO)2 was replaced by ZnCl2.

[0045] Battery device performance analysis:

[0046] Figure 3 This is the JV curve of the copper-zinc-tin-sulfur-selenium thin film solar cell. The corresponding device performance parameters are listed in Table 2.

[0047] Table 2 Photovoltaic performance parameters of copper-zinc-tin-sulfur-selenium solar cells

[0048]

[0049] It can be concluded from Table 2 that the efficiency of the solar cell devices of Examples 7-9 are 11.65%, 11.50% and 11.37% respectively, which are significantly better than the 7.14% efficiency of Comparative Example 2. This indicates that the precursor solution containing oxygen-containing acid radicals (acetate radical, sulfate radical, etc.) is also suitable for improving the efficiency of copper-zinc-tin-sulfur-selenium solar cells.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A precursor solution for inorganic compound thin film solar cells, characterized in that: The invention comprises the following raw materials: a metal precursor compound, a sulfur-containing ligand and a solvent; the metal in the metal precursor compound comprises indium, gallium and copper or zinc, tin and copper; the metal precursor compound further comprises one or more of sulfate, acetate and nitrate.

2. The precursor solution for inorganic compound thin film solar cells according to claim 1, characterized in that: The molar ratio of copper, indium, gallium and sulfur in the sulfur-containing ligand is 1:0.7-1:0-0.3:5-6.

3. The precursor solution for inorganic compound thin film solar cells according to claim 1, characterized in that: The molar ratio of the copper, zinc, tin and sulfur in the sulfur-containing ligand is 1:0.6-1:0.6-1:3-4.

4. The precursor solution for inorganic compound thin film solar cells according to claim 1, characterized in that: The sulfur-containing ligand includes thiourea.

5. The precursor solution for inorganic compound thin film solar cells according to claim 1, characterized in that: The solvents include N,N-dimethylformamide and dimethyl sulfoxide.

6. A method for preparing a precursor solution for an inorganic compound thin film solar cell, characterized in that: The solvent is added to the sulfur-containing ligand, stirred, and then the metal precursor compound is added and stirred until the compound is dissolved to obtain a precursor solution.

7. The method for preparing a precursor solution for an inorganic compound thin film solar cell according to claim 6, characterized in that: The solvents include N,N-dimethylformamide and dimethyl sulfoxide.

8. The method for preparing a precursor solution for an inorganic compound thin film solar cell according to claim 6, characterized in that: The sulfur-containing ligand includes thiourea.

9. Use of the precursor solution according to any one of claims 1 to 5 or the precursor solution prepared by the preparation method according to any one of claims 6 to 8 in the production of solar cells.

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