Precursor solution for inorganic compound thin film solar cell, preparation method therefor and use thereof

Abstract

The present invention belongs to the field of thin film solar cells. Disclosed are a precursor solution for an inorganic compound thin film solar cell, a preparation method therefor and the use thereof. The precursor solution for an inorganic compound thin film solar cell comprises the following raw materials: a metal precursor compound, a sulfur-containing ligand and a solvent. 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. The precursor solution of the present invention avoids complex chemical reactions in thin film forming processes, forms absorption layer thin films having large grains, no impurity and flat surfaces, and improves the photoelectric conversion efficiency of inorganic compound thin film solar cells.

Description

A precursor solution for inorganic compound thin-film solar cells, its preparation method and its application Technical Field

[0001] This invention belongs to the field of thin-film solar cells, specifically relating to a precursor solution for inorganic compound thin-film solar cells, its preparation method, and its application. Background Technology

[0002] Solar energy is an inexhaustible energy source. Developing this 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 solar energy conversion in recent years, is a very promising direction. To date, many types of solar cells have been developed and commercialized. Among them, crystalline silicon solar cells have accounted for more than 90% of the commercial photovoltaic market. However, the manufacturing of crystalline silicon cells requires very thick wafers and high-temperature / vacuum processes, resulting in high costs and limiting their application in flexible and lightweight battery devices. Developing thin-film photovoltaic technology is crucial for expanding the photovoltaic market. Inorganic compound thin films, due to their environmental friendliness and high stability, are a research hotspot in the field of thin-film photovoltaics.

[0003] The preparation processes of inorganic compound thin films can generally be divided into two categories: vacuum methods and non-vacuum methods. Vacuum methods produce high-quality films, but require expensive high-vacuum equipment, resulting in high energy consumption and low material utilization. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a precursor solution for inorganic compound thin-film solar cells, its preparation method, and its applications.

[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 includes indium, gallium, and copper, or zinc, tin, and copper; the metal precursor compound also includes 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 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 includes thiourea.

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

[0010] A method for preparing a precursor solution for inorganic compound thin-film solar cells involves adding a solvent to a sulfur-containing ligand, stirring, then adding a metal precursor compound, and stirring until the compound dissolves to obtain the precursor solution.

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

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

[0013] This invention provides a precursor solution for preparing inorganic compound thin-film solar cells. By replacing the metal precursor compound containing acetate, sulfate, or nitrate ions, or by adding an oxyacid to introduce acetate, sulfate, or nitrate ions, the metal ions in the solution are pre-associated using the strong coordination ability and hydrogen bonding of oxygen atoms, forming a stable and uniform network macromolecular structure. This method avoids the aggregation of metal elements, thereby avoiding the complex chemical reactions in the thin-film formation process, resulting in a large-grained, impurity-free, and smooth-surfaced absorption layer film, thus improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

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

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

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

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1

[0020] Using 6 mL of N,N-dimethylformamide as a solvent, first add 0.033 mol of thiourea and stir continuously until the solution is clear and transparent. Then add 0.0042 mol of InCl3·4H2O and 0.0018 mol of CaCl3, and continue stirring until the solution is clear and transparent. 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), and continue stirring until the solution turns pale yellow and a yellow precipitate forms. After filtering the prepared solution through a 0.8 μm filter, the solution is coated onto a cleaned molybdenum-plated sodium-calcium glass substrate using a scraping method. The sample is then annealed on a hot stage at 340℃ for 1 min and removed. After the sample cools, the above scraping-annealing process is repeated 5 times to obtain the precursor film. Next, the precursor film was placed in a covered graphite box with 0.35 g of selenium granules added, and then placed in a tube furnace. Under argon protection, it was annealed at 590 °C for 18 min (selenization) to obtain a copper indium gallium selenide (CIGS) absorber layer film. The morphology of the CIGS absorber layer films obtained in each example and comparative example was analyzed using 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 CIGS absorber layer film to fabricate a solar cell device. The fabricated cell was placed on a solar cell platform, and the probes of the test platform were attached to the positive and negative electrodes of the cell, respectively. The probe wires were then connected to a Keithley 2400 data source table. The accompanying test software was opened on the computer, and the temperature was 25 °C, with an irradiance of 100 mW / cm² generated by the AAA solar simulator (CROWNTECH. Inc.). 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 table 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] Repeat Example 1 using the same steps. The difference is that 0.03 mol of thiourea, 0.0045 mol of InCl3·4H2O, and 0.0015 mol of GaCl3 are added (the molar ratio of each element in the solution is Cu:In:Ga:S = 1:0.75:0.25:5).

[0023] Example 3

[0024] Repeat Example 1 using the same steps. The difference is that 0.036 mol of thiourea is added, 0.0042 mol of InCl3·4H2O is added, and GaCl3 is not added (the molar ratio of each element in the solution is Cu:In:Ga:S=1:1:0:6).

[0025] Example 4

[0026] Repeat Example 1 using the same steps. The difference is that Cu(CH3COO)2·H2O is replaced with CuSO4.

[0027] Example 5

[0028] Repeat Example 1 using the same steps. The difference is that Cu(CH3COO)2·H2O is replaced with CuCl, and 0.012 mol of acetic acid is added to the solution.

[0029] Comparative Example 1

[0030] Repeat Example 1 using the same steps. The difference is that Cu((CH3COO))2·H2O is replaced with CuCl.

[0031] Thin film morphology analysis:

[0032] Figure 1 shows a comparison of surface SEM images of the copper indium gallium selenide (CIGS) absorber layer films. It can be seen that the grain size of the films in Examples 1-5 is significantly larger than that in Comparative Example 1, and the grain size is more uniform. The film surface is smoother, with complete coverage, no pores, and no impurity particles.

[0033] Battery device performance analysis:

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

[0035] Table 1 Photovoltaic performance parameters of copper indium gallium selenide solar cells

[0036] Table 1 shows that the efficiencies of the solar cell devices in Examples 1-5 are 15.95%, 15.63%, 15.73%, and 15.09%, respectively, which are significantly better than the 11.97% efficiency of Comparative Example 1. These results indicate that introducing precursor solutions containing oxyacids (acetate, sulfate, etc.) can prepare absorber films with larger grain sizes, smoother surfaces, and no impurities, thereby improving the photoelectric conversion efficiency of the cell. This is because the oxygen atoms in oxyacids have strong coordination ability and hydrogen bonding, which can pre-associate metal ions in the solution, forming a stable and uniform network macromolecular structure. This reduces the aggregation and ionization of metal ions, thus avoiding complex chemical reactions during film formation, reducing impurities in the film, improving phase purity, and forming a large-grained, impurity-free absorber film with a smooth surface, thereby improving the photoelectric conversion efficiency of the solar cell.

[0037] Example 6

[0038] Take 4 mL of dimethyl sulfoxide and add 0.0184 mol of thiourea. Stir rapidly until the thiourea is completely dissolved. Then add water until the solution is clear and transparent. Next, add 0.006 mol of CuCl to obtain solution 1. Separately, take 4 mL of dimethyl sulfoxide and mix with 0.0036 mol of SnCl4. Stir rapidly until the solution 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 to obtain solution 2. Finally, mix solution 1 and solution 2 and stir well to obtain a pale yellow precursor solution. The solution was filtered through a 0.8-micron filter and then dropped onto a cleaned molybdenum-plated sodium-calcium glass substrate. A wet film was prepared by spin coating at 2000 rpm for 30 seconds. Immediately after spin coating, the wet film was transferred to a 340°C heating stage for annealing for 1.5 minutes. This spin-coating-annealing process was repeated 7 times to obtain the precursor film. Subsequently, the precursor film was placed in a covered graphite box with 0.5 g of selenium granules added, and then placed in a tube furnace. Under argon protection, it was annealed at 540°C for 20 minutes (selenization) to obtain a copper-zinc-tin-sulfur-selenium absorber layer film. A CdS buffer layer, a ZnO / ITO window layer, and a Ni / Al metal electrode were sequentially deposited on the obtained copper-zinc-tin-sulfur-selenium absorber layer film to fabricate a solar cell device. The solar cell was tested at a light intensity of 100 mW / cm². 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).

[0039] Example 7

[0040] Repeat Example 6 using the same steps. The difference is 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).

[0041] Example 8

[0042] Example 6 was repeated using the same steps. The difference was that 0.024 mol of thiourea, 0.0042 mol of SnCl4, and 0.0042 mol of Zn(CH3COO)2 were added (the molar ratio of Cu:Sn:Zn:S in the solution was 1:0.7:0.7:4). Comparative Example 2

[0043] Repeat Example 3 using the same steps. The difference is that the added Zn(CH3COO)2 is replaced with ZnCl2.

[0044] Battery device performance analysis:

[0045] Figure 3 shows the JV curve of a copper-zinc-tin-sulfur-selenium thin-film solar cell, and the corresponding device performance parameters are listed in Table 2.

[0046] Table 2 Photovoltaic performance parameters of copper-zinc-tin-sulfur-selenium solar cells

[0047] Table 2 shows that the efficiencies of the solar cell devices in 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 oxyacid anions (acetate, sulfate, etc.) is also suitable for improving the efficiency of copper-zinc-tin-sulfur-selenium solar cells.

[0048] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] The foregoing has shown and described 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. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A precursor solution for a thin film solar cell of inorganic compound, characterized by, It includes the following raw materials: a metal precursor compound, a sulfur-containing ligand, and a solvent; the metal in the metal precursor compound includes indium, gallium, and copper or zinc, tin, and copper; the metal precursor compound also includes one or more of sulfate, acetate, and nitrate.

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

4. The precursor solution for thin film solar cell of inorganic compound according to claim 1, wherein The sulfur-containing ligands include thiourea.

5. The precursor solution for thin film solar cell of inorganic compound according to claim 1, wherein The solvent includes N,N-dimethylformamide and dimethyl sulfoxide.

6. A method for preparing a precursor solution for a thin film solar cell of inorganic compound, characterized by, The solvent was added to the sulfur-containing ligand and stirred. Then the metal precursor compound was added and stirred until the compound dissolved to obtain the precursor solution.

7. The method of claim 6, wherein the solution is prepared by dissolving the inorganic compound in the solvent. The solvent includes N,N-dimethylformamide and dimethyl sulfoxide.

8. The method of claim 6, wherein the solution is prepared by dissolving the inorganic compound in a solvent. The sulfur-containing ligands include thiourea.

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

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