Preparation Method and Application of Perovskite Precursor Solution

Abstract

The present invention provides a method for preparing a perovskite precursor solution and its application, relating to the technical field of perovskite solar cells. The method comprises the following steps: (1) Weigh FaI and PbI2, dissolve them in 2ME, and stir evenly to obtain a 2ME solution of FAPbI3; (2) Weigh MaI and PbI2, dissolve them in 2ME, and stir evenly to obtain a 2ME solution of MAPbI3; (3) Weigh CsI and PbI2, dissolve them in a mixed solution of DMF and DMSO, and stir evenly to obtain a mixed solution of CsPbI3 in DMF and DMSO; (4) Mix the above three solutions in a mass ratio of 16:3:1, and stir evenly to obtain a FA 0.8 MA 0.15 Cs 0.05 PbI3 precursor solution. The present invention can be well dissolved in a low-coordination solvent, which helps the perovskite crystals to nucleate rapidly, with uniform nucleation and consistent color, no color difference, and is suitable for the implementation of roll-to-roll production processes for large-area solar devices or flexible solar substrate cells.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cells, and particularly relates to a preparation method and application of a perovskite precursor solution. Background Art

[0002] As a green energy source that is almost inexhaustible, how to effectively utilize solar energy has always been a research hotspot. Since the 1950s, solar cells have developed to the fourth generation, namely the first-generation crystalline silicon solar cells, the second-generation compound thin-film solar cells, the third-generation polymer solar cells, and the fourth-generation sensitized solar cells.

[0003] Perovskite solar cells generally use organic-inorganic hybrid crystalline materials, such as organometallic trihalides, as light-absorbing materials. It has a suitable energy band structure, and due to its match with the solar spectrum, it has good light absorption performance. A very thin thickness can absorb almost all visible light and be used for photoelectric conversion.

[0004] Currently, among the preparation methods of perovskite solar cells, the solution method is a widely used method, and high-efficiency and stable perovskite solar cells can be obtained.

[0005] In the solution used in the solution method, conventional solvents such as DMF, DMSO, and GBL have high boiling points, slow evaporation rates, and are toxic. They cannot promote the rapid nucleation of perovskite crystals and are only suitable for small-area laboratory preparation and laboratory preparation, and are not suitable for blade coating and industrial large-area production. Among low-coordination solvents, the currently mainstream 2ME is more suitable for single-component perovskite, namely the formamidinium, methylammonium system.

[0006] Patent CN 112071982 B discloses a highly stable formamidinium perovskite material, its preparation method, and uses. The preparation method includes the following steps: Step 1, mixing a divalent metal halide, formamidinium hydrohalide, and a specific additive, and dissolving them in a large-polarity solution to obtain a precursor solution; Step 2, using a spin coating, blade coating, or spraying process to form a film from the precursor solution, removing the large-polarity solution by heating or anti-solvent rinsing, and heating the film at 150 °C to obtain the formamidinium perovskite material.

[0007] Another example is that patent CN 112952003 A discloses a formamidinium-based perovskite film, a perovskite battery module, and its preparation method. The preparation raw materials of the formamidinium-based perovskite film include a formamidinium-based perovskite precursor solution, and the perovskite precursor solution contains perovskite components and a high-donor-number solvent; the formamidinium-based perovskite precursor solution is coated, and after drying and annealing treatment, a formamidinium-based perovskite film is obtained.

[0008] The solution method for preparing perovskite thin films generally requires thermal annealing treatment to promote crystallization and growth. Research based on conductive scanning probe technology has shown that while thermal annealing induces film crystallization, it also causes the fusion of material grain boundaries, effectively promoting the splitting of electrons and holes at the grain boundaries. However, at the same time, the thermally induced stress will also cause the structural instability of the perovskite material in essence.

[0009] Perovskite with formamidine as the main system is mainly used in the production of solar cell products with rigid substrates due to high-temperature annealing (150 °C and above). For flexible substrate solar cells, since their flexible substrates cannot withstand high temperatures, it is not conducive to the preparation of flexible thin-film solar cells. In the preparation of flexible substrate solar cells, it is necessary to introduce inorganic metal ion Cs+ to lower the annealing temperature, introduce methylamine ions to stabilize the phase, and introduce other cations to form a triple-cation system.

[0010] However, the currently low-coordination solvent 2ME applicable to the preparation process of large-area perovskite solar cells cannot effectively dissolve the triple-cation system precursor. Even if it is dissolved, the prepared perovskite thin film has the problem of a mixed yellow and black phase, which affects the appearance of the solar cell and its power generation efficiency at the same time.

[0011] In summary, how to provide a preparation method for a triple-cation system precursor solution applicable to the preparation process of flexible perovskite solar cells is a technical problem that urgently needs to be solved at present. Summary of the Invention

[0012] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a preparation method and application of a perovskite precursor solution, which can be used to obtain a perovskite thin-film solar cell with a black phase.

[0013] The present invention provides a preparation method for a perovskite precursor solution, including the following steps:

[0014] (1) Weigh FaI and PbI2, dissolve them in 2ME (ethylene glycol methyl ether), and stir evenly to obtain a 2ME solution of FAPbI3;

[0015] (2) Weigh MaI and PbI2, dissolve them in 2ME (ethylene glycol methyl ether), and stir evenly to obtain a 2ME solution of MAPbI3;

[0016] (3) Weigh CsI and PbI2, dissolve them in a mixed solution of DMF and DMSO, and stir evenly to obtain a mixed solution of CsPbI3 in DMF and DMSO;

[0017] (4) Mix the 2ME solution of FAPbI3 in step (1), the 2ME solution of MAPbI3 in step (2), and the mixed solution of DMF and DMSO of CsPbI3 in step (3) in a mass ratio of 16:3:1, and stir evenly to obtain a FA 0.8 MA 0.15 Cs 0.05 PbI3 precursor solution.

[0018] Furthermore, in step (1), weigh out FaI and PbI2, dissolve them in 2ME (ethylene glycol methyl ether), and stir at room temperature for 12 - 14 hours.

[0019] Furthermore, in step (2), weigh out MaI and PbI2, dissolve them in 2ME (ethylene glycol methyl ether), and stir at room temperature for 12 - 14 hours.

[0020] Furthermore, in step (3), weigh out MaI and PbI2, dissolve them in the mixed solution of DMF and DMSO, and stir at room temperature for 12 - 14 hours.

[0021] Furthermore, in step (3), the mixed solution of DMF and DMSO is obtained by mixing DMF and DMSO in a volume ratio of 4:1 and stirring evenly.

[0022] The present invention also provides a method for preparing a perovskite thin film, comprising the following steps:

[0023] (A) Obtain a perovskite precursor solution, and the perovskite precursor solution is the perovskite precursor solution described in any one of the above;

[0024] (B) After coating the perovskite precursor solution in step (A) onto a flexible substrate, perform annealing treatment to obtain a perovskite thin film.

[0025] Furthermore, in step (B), after coating the perovskite precursor solution onto a flexible substrate, spin coating treatment or blade coating treatment is adopted.

[0026] Furthermore, in step (B), the annealing temperature is 100°C - 120°C.

[0027] Furthermore, in step (B), the annealing time is 5 minutes - 10 minutes.

[0028] Due to the adoption of the above technical solutions, compared with the prior art, the present invention has the following advantages and positive effects by way of example:

[0029] The perovskite precursor solution obtained by the preparation method provided by the present invention dissolves well in a low-coordination solvent, thus avoiding turbidity or the appearance of a yellow-black mixed phase, and can be used in the production of pure black-phase perovskite thin-film solar cells, reducing the color difference problem, not affecting the appearance of the perovskite solar cell, and also not affecting its power generation efficiency.

[0030] In addition, the perovskite precursor solution obtained by the preparation method provided by the present invention has a low boiling point and fast evaporation rate, which helps the perovskite crystals to nucleate rapidly, and has the characteristics of consistency, with uniform nucleation and consistent color, no color difference, and can be used in the production of large-area solar devices by the doctor blade method or brush coating method, and can be used in the roll-to-roll production process of flexible solar substrate batteries, which is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 XRD characterization diagram of the perovskite thin film prepared in Example 1.

[0032] Figure 2 SEM morphology diagram of the perovskite thin film prepared in Example 2.

[0033] Figure 3 XRD characterization diagram of the perovskite thin film prepared in Example 3.

[0034] Figure 4 SEM morphology diagram of the perovskite thin film prepared in Example 4.

[0035] Figure 5 XRD characterization diagram of the perovskite thin film prepared in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0036] The following further describes in detail the technical solutions disclosed by the present invention in combination with specific embodiments.

[0037] For technologies and methods known to those of ordinary skill in the relevant art, detailed discussion may not be made, but in appropriate cases, such technologies and methods should be regarded as part of the specification. In all examples shown and discussed here, any specific value should be construed as merely exemplary, not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0038] The present invention provides a preparation method for a perovskite precursor solution, comprising the following steps:

[0039] (1) Weigh FaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), stir evenly to obtain a 2ME solution of FAPbI3;

[0040] (2) Weigh out MaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir evenly to obtain a 2ME solution of MAPbI3;

[0041] (3) Weigh out CsI and PbI2, dissolve them in a mixed solution of DMF and DMSO, and stir evenly to obtain a mixed solution of CsPbI3 in DMF and DMSO;

[0042] (4) Mix the 2ME solution of FAPbI3 in step (1), the 2ME solution of MAPbI3 in step (2), and the mixed solution of CsPbI3 in DMF and DMSO in step (3) according to the mass ratio of 16:3:1, and stir evenly to obtain a precursor solution of FA 0.8 MA 0.15 Cs 0.05 PbI3 precursor solution.

[0043] In step (1), weigh out FaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir at room temperature for 12 - 14 hours.

[0044] In step (2), weigh out MaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir at room temperature for 12 - 14 hours.

[0045] In step (3), weigh out MaI and PbI2, dissolve them in a mixed solution of DMF and DMSO, and stir at room temperature for 12 - 14 hours.

[0046] In step (3), the mixed solution of DMF and DMSO is obtained by mixing DMF and DMSO according to the volume ratio of 4:1 and stirring evenly.

[0047] A method for preparing a perovskite thin film provided by the present invention includes the following steps:

[0048] (A) Obtain the above-mentioned perovskite precursor solution;

[0049] (B) After coating the perovskite precursor solution in step (A) onto a flexible substrate, perform annealing treatment to obtain a perovskite thin film.

[0050] In step (B), after coating the perovskite precursor solution onto a flexible substrate, spin coating or blade coating is used.

[0051] The temperature of the annealing treatment is 100°C - 120°C.

[0052] The time of the annealing treatment is 5 minutes - 10 minutes.

[0053] Example 1

[0054] Weigh 0.172 g FaI and 0.461 g PbI2, dissolve in 1 ml 2ME, and stir overnight at room temperature on a magnetic stirrer to obtain a 2ME solution of FAPbI3.

[0055] Weigh 0.159 g MaI and 0.461 g PbI2 and dissolve them in 1 ml 2ME. Stir them overnight at room temperature on a magnetic stirrer to obtain a 2ME solution of MAPbI3.

[0056] Weigh 0.2598 g of CsI and 0.461 g of PbI2 and dissolve them in a mixture of DMF and DMSO (4:1), stir them at room temperature overnight on a magnetic stirrer to obtain a DMF&DMSO mixed solution of CsPbI3.

[0057] The three perovskite precursor solutions were taken by pipette according to the metering ratio, 80% of the target solution volume of FAPbI3 2ME solution, 15% of the target solution volume of MAPbI3 2ME solution, and 5% of the target solution volume of CsPbI3 DMF & DMSO mixed solution, and mixed to prepare FA 0.8 MA 0.15 Cs 0.05 PbI3 precursor solution.

[0058] Example 2

[0059] Take FA in Example 1 0.8 MA 0.15 Cs 0.05 50ul of PbI3 precursor solution was dripped onto the flexible substrate and scraped at a speed of 10mm / s with a wind knife with a wind volume of 0.2mPa to obtain a dry film. In an external environment of 15-20% RH, the film was prepared to be reddish brown. The dry film was then annealed at 100°C for 2min and turned black, obtaining a pure black perovskite film.

[0060] Attached Figure 1 This is the XRD characterization diagram of the obtained perovskite film.

[0061] If a peak appears between 10-12°, it indicates the presence of a yellow phase. If a peak appears near 14°, the XRD characterization result indicates a black phase.

[0062] Attached Figure 2 This is the SEM morphology of the obtained perovskite film.

[0063] Example 3

[0064] Weigh 0.172 g FaI and 0.461 g PbI2, dissolve in 1 ml 2ME, and stir overnight at room temperature on a magnetic stirrer to obtain a 2ME solution of FAPbI3.

[0065] Weigh 0.159 g MaI and 0.461 g PbI2 and dissolve them in 1 ml 2ME. Stir them overnight at room temperature on a magnetic stirrer to obtain a 2ME solution of MAPbI3.

[0066] Weigh 0.2598 g of CsI and 0.461 g of PbI2 and dissolve them in a mixture of DMF and DMSO (4:1), stir at room temperature overnight to obtain a DMF & DMSO mixed solution of CsPbI3.

[0067] Mix according to the metering ratio to prepare FA 0.8 MA 0.15 Cs 0.05 PbI3 precursor solution.

[0068] Example 4

[0069] Take FA in Example 3 0.8 MA 0.15 Cs 0.05 100ul of PbI3 precursor solution was dropped onto the flexible substrate and spin-coated at 5000rpm for 50s to obtain a dry film. Under an external environment of 15-20% RH, the film was reddish brown after preparation. The dry film was then annealed at 100°C for 2min and turned black, obtaining a pure black perovskite film.

[0070] Attached Figure 3 This is the XRD characterization diagram of the obtained perovskite film. The peak appears near 14° and the XRD characterization result is a black phase.

[0071] Attached Figure 4 This is the SEM morphology of the obtained perovskite film.

[0072] Comparative Example 1

[0073] Weigh 0.1376g FAI, 0.0239g MAI, 0.013g CsI and 0.461g PbI2 and dissolve them in 1ml 2ME solution. Stir overnight at room temperature. The solution becomes turbid and cannot be dissolved.

[0074] Comparative Example 2

[0075] Weigh 0.1445g FaI, 0.0254g MAI and 0.461g PbI 2， Dissolve in 1 ml 2ME solution and stir overnight at room temperature; weigh 0.013 g CsI and 0.461 g PbI 2， Dissolved in 1 ml of DMF and DMSO mixed solution (4:1).

[0076] Mix the above two solutions in a ratio of 19:1 to prepare FA 0.8 MA0.15 Cs 0.05 Precursor solution. Take 100 μl and drop it onto the flexible substrate, spin-coat at 5000 rpm for 50 s, and then anneal at 100 °C for 2 min to obtain a perovskite film.

[0077] Appendix Figure 5 XRD characterization of the obtained perovskite film, which is a yellow-black mixed phase.

[0078] In summary, the perovskite precursor solution prepared by the preparation method provided by the present invention has good solubility in the 2ME solution.

[0079] Using this perovskite precursor solution and through the preparation method of the perovskite film provided by the present invention, a perovskite film with a black phase can be prepared.

[0080] Within the scope of the object of the present disclosure, terms such as "including" should be construed as inclusive or open by default, rather than exclusive or closed, unless it is explicitly defined to have the opposite meaning. All technical, scientific, or other terms conform to the meaning understood by those skilled in the art, unless it is defined to have the opposite meaning. Common terms found in the dictionary should not be construed too idealistically or too unrealistically in the context of the relevant technical documents, unless the present disclosure clearly defines it as such.

[0081] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0082] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a perovskite precursor solution, characterized in that, It includes the following steps: (1) Weigh FaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir evenly to obtain a 2ME solution of FAPbI3; (2) Weigh MaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir evenly to obtain a 2ME solution of MAPbI3; (3) Weigh CsI and PbI2, dissolve them in a mixed solution of DMF and DMSO, and stir evenly to obtain a mixed solution of CsPbI3 in DMF and DMSO; (4) Mix the 2ME solution of FAPbI3 in step (1), the 2ME solution of MAPbI3 in step (2), and the mixed solution of DMF and DMSO of CsPbI3 in step (3) in a mass ratio of 16:3:1, and stir evenly to obtain a FA 0.8 MA 0.15 Cs 0.05 PbI3 precursor solution.

2. The method for preparing a perovskite precursor solution according to claim 1, characterized in that: In step (1), weigh FaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir at room temperature for 12 - 14 hours.

3. The method for preparing a perovskite precursor solution according to claim 1, characterized in that: In step (2), weigh MaI and PbI2, dissolve them in 2ME (ethylene glycol monomethyl ether), and stir at room temperature for 12 - 14 hours.

4. The method for preparing a perovskite precursor solution according to claim 1, characterized in that: In step (3), weigh MaI and PbI2, dissolve them in a mixed solution of DMF and DMSO, and stir at room temperature for 12 - 14 hours.

5. The method for preparing a perovskite precursor solution according to claim 1, characterized in that: In step (3), the mixed solution of DMF and DMSO is obtained by mixing DMF and DMSO in a volume ratio of 4:1 and stirring evenly.

6. A method for preparing a perovskite thin film, characterized in that, It includes the following steps: (A) Obtain a perovskite precursor solution, which is the perovskite precursor solution described in any one of claims 1 - 5; (B) After coating the perovskite precursor solution in step (A) onto a flexible substrate, perform annealing treatment to obtain a perovskite thin film.

7. The method for preparing a perovskite thin film according to claim 6, characterized in that: In step (B), after coating the perovskite precursor solution onto a flexible substrate, spin coating treatment or blade coating treatment is adopted.

8. The method for preparing a perovskite thin film according to claim 6, characterized in that: In step (B), the temperature of the annealing treatment is 100°C - 120°C.

9. The method for preparing a perovskite thin film according to claim 6, characterized in that: In step (B), the time of the annealing treatment is 5 minutes - 10 minutes.

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