Precursor solution preparation method and perovskite solar cell preparation method

Abstract

The invention discloses a precursor solution preparation method and a perovskite solar cell preparation method. The method comprises the following steps: preparing a perovskite precursor solution by taking dimethyl sulfoxide, 2-methyltetrahydrofuran and gamma-valerolactone as solvents; and adding a perovskite material into the solvent to form a perovskite precursor solution. A full-green solvent system composed of dimethyl sulfoxide, 2-methyltetrahydrofuran and gamma-valerolactone is adopted to prepare a precursor solution, the perovskite solar cell is prepared from the precursor solution, a specific solvent combination is matched with a corresponding coating rate and regulation and control crystallization kinetics, and a uniform and compact high-quality perovskite thin film can be prepared on a large area. The device efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a method for preparing a precursor solution and a method for preparing perovskite solar cells. Background Technology

[0002] The development of perovskite solar cells heavily relies on solution-based fabrication techniques for high-quality thin films. Traditional solvents used in perovskite thin film fabrication, such as N,N-dimethylformamide (DMF), 2-methoxyethanol (2-ME), and N-methylpyrrolidone (NMP), are volatile organic compounds (VOCs) or highly toxic, impacting the health of production workers. Production workshops require costly waste gas treatment systems, increasing manufacturing costs and failing to meet green manufacturing requirements. Furthermore, the slow evaporation rates of existing solvent systems are mismatched with the crystallization kinetics of perovskite, easily leading to defects such as voids at the bottom of the film and uneven coverage, restricting device performance and product yield. Moreover, the solvent systems lack adaptability to large-area film deposition processes, making it difficult to ensure film uniformity while increasing coating speed, ultimately affecting the performance of the final solar cell.

[0003] Based on the above problems, there is a need to provide a method for preparing precursor solutions and a method for preparing perovskite solar cells that takes into account the characteristics of low toxicity, rapid volatilization and crystallization control, so as to achieve the preparation of efficient, stable and large-area perovskite solar cells. Summary of the Invention

[0004] The purpose of this invention is to solve all or part of the above-mentioned problems by providing a precursor solution preparation method and a perovskite solar cell fabrication method. This method utilizes a fully green solvent system composed of dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerolactone, meeting the core industrialization requirements of environmental protection and safe production. This green solvent combination, combined with a slot coating process, optimizes crystallization kinetics, enabling the preparation of uniform, pore-free, high-quality perovskite films. This ensures the good crystallinity of the perovskite film, achieving the fabrication of high-efficiency, high-stability perovskite solar cell modules.

[0005] This invention provides a precursor solution preparation method, comprising the following steps: preparing a perovskite precursor solution using dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol as solvents; adding perovskite material to the solvents to form the perovskite precursor solution. The use of a completely green solvent system composed of dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol eliminates traditional toxic solvents, meeting the requirements of environmental protection and industrial production; and utilizing this solvent system to regulate crystallization kinetics, resulting in the preparation of uniform, dense, high-quality perovskite thin films.

[0006] The volume ratio of dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerolactone in the solvent is 1:(1~3):(1~3). This appropriate solvent ratio ensures that dimethyl sulfoxide provides strong coordination ability while 2-methyltetrahydrofuran effectively regulates the coordination strength and evaporation rate of γ-valerolactone, optimizing crystallization kinetics. Optimizing the ratio effectively avoids the problem of bottom pores in perovskite films caused by excessively slow solvent evaporation or excessively strong coordination, resulting in uniform, dense, and high-quality films.

[0007] The concentration of the perovskite precursor solution was 0.6–1 mol / L. This optimized crystallization kinetics and film quality, facilitating subsequent control of film thickness and ensuring film quality.

[0008] A method for fabricating a perovskite solar cell is also provided, comprising the following steps: S1: providing a conductive substrate and depositing a hole transport layer on the conductive substrate; S2: preparing a perovskite precursor solution using dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol as solvents, and forming a perovskite thin film on the hole transport layer; S3: forming an electron transport layer on the perovskite thin film; S4: forming an electrode layer on the electron transport layer. This solvent combination, combined with a corresponding coating rate, effectively controls crystallization kinetics, resulting in a uniform, dense, high-quality perovskite thin film, thus improving device efficiency; it is also suitable for producing large-area perovskite solar cell modules.

[0009] Before depositing the hole transport layer, the conductive substrate is scribing line P1; before forming the electrode layer, the electron transport layer is scribing line P2; after forming the electrode layer, the electrode layer is scribing line P3. The device is divided into multiple sub-cells to achieve a high output voltage for the perovskite solar cell.

[0010] In step S2, the volume ratio of dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol in the perovskite precursor solution is 1:(1~3):(1~3). Optimizing the solvent ratio and crystallization kinetics avoids the formation of pores at the bottom of the perovskite film, resulting in a uniform, dense, and high-quality film.

[0011] The perovskite thin film formation process is as follows: A perovskite precursor solution is coated onto the hole transport layer at a coating rate of 15-25 mm / s, followed by annealing at 130°C for 15-20 min to obtain the perovskite thin film. A high coating rate reduces the impact of wet film evaporation in air on perovskite crystallization; suitable heat treatment conditions promote grain growth and fusion, resulting in a uniform and dense thin film morphology and improved device performance.

[0012] The perovskite thin film has a thickness of 400 nm. This ensures the stability and uniformity of the film, thereby improving the reliability of the device.

[0013] The electron transport layer comprises sequentially deposited C 60 Electron transport layer and SnO2 electron transport layer; the C 60 The electron transport layer has a thickness of 10-30 nm, and the SnO2 electron transport layer has a thickness of 10-30 nm. This achieves a balance between charge extraction and conductivity, ensuring smooth charge transport.

[0014] The electrode layer is made of copper with a thickness of 100-200 nm. This forms a continuous, low-resistance conductive channel, reducing series resistance; it also facilitates uniform and controllable deposition over a large area, providing a key guarantee for the efficient, low-cost, and high-yield manufacturing of perovskite solar modules.

[0015] Compared with the prior art, the beneficial effects of the present invention are: it provides a method for preparing a precursor solution and a method for preparing perovskite solar cells, using a completely green solvent system composed of dimethyl sulfoxide, 2-methyltetrahydrofuran and γ-valerol, abandoning traditional toxic solvents and meeting the requirements of environmental protection and industrial production; this solvent combination, combined with a corresponding coating rate, effectively controls the crystallization kinetics, enabling the preparation of uniform, dense, high-quality perovskite thin films on a large area, thereby improving device efficiency; it is also suitable for the production of large-area perovskite solar cell modules. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The image shows a SEM image of the perovskite thin film prepared with the solvent in Example 1.

[0018] Figure 2 SEM images of perovskite films prepared with the solvent in the comparative example.

[0019] Figure 3 The image shows the XRD pattern of the perovskite thin film prepared by the solvent in Example 1.

[0020] Figure 4 The PL spectrum of the perovskite thin film prepared with the solvent in Example 1.

[0021] Figure 5 The graphs show the performance of the perovskite solar cells prepared in Examples 2-4 and the comparative examples. Detailed Implementation

[0022] The following description and accompanying drawings fully illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Some portions and features of some embodiments may be included in or replace portions and features of other embodiments.

[0023] Example 1 This embodiment provides a method for preparing a precursor solution, including the following steps: preparing a perovskite precursor solution using dimethyl sulfoxide (DMSO), 2-methyltetrahydrofuran (2-MeTHF), and γ-valerol (GVL) as solvents; adding perovskite material to the solvents to form a perovskite precursor solution; the volume ratio of DMSO, GVL, and 2-MeTHF is 1:(1~3):(1~3); in this embodiment, the concentration of the perovskite precursor solution is 0.6~1 mol / L, and the volume ratio of DMSO, GVL, and 2-MeTHF is 1:2:2.

[0024] Example 2 This embodiment provides a method for preparing a perovskite solar cell. Using the perovskite precursor solution described in Example 1, a 30cm × 40cm perovskite solar cell is prepared, including the following steps: S1: Provide a 30cm×40cm conductive substrate, perform P1 scribing on the conductive substrate, and ultrasonically treat the P1 scribing conductive substrate in deionized water, detergent and isopropanol for 15min respectively. Dry the cleaned conductive substrate with nitrogen gas; form a hole transport layer on the conductive substrate. In this embodiment, the conductive substrate is an FTO glass substrate, and the hole transport layer is nickel oxide. S2: A perovskite precursor solution was prepared using dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol as solvents, wherein the volume ratio of DMSO, GVL, and 2-MeTHF was 1:2:2, and Cs was selected as the perovskite material. 0.05 FA 0.95 PbI3 at a concentration of 0.6 mol / L was used to prepare a perovskite film on the hole transport layer using a slit coating method at a coating speed of 16 mm / s. The perovskite film with a thickness of 400 nm was obtained by super vacuum drying (VCD) to assist solvent evaporation and perovskite crystallization, followed by heating on a hot stage at 130 °C for 15 min. S3: Forming an electron transport layer on the perovskite film, specifically including depositing a C layer on the perovskite film using a vacuum method. 60 Atomic deposition method was used in C 60 Depositing a layer of SnO2, in this embodiment, C 60The thickness is 26nm, and the SnO2 thickness is 16nm; the electron transport layer is scribed with P2 lines. S4: A Cu electrode layer with a thickness of 200 nm is prepared on the electron transport layer by thermal evaporation. The electrode layer is then scribed with P3 lines and encapsulated to obtain a perovskite solar cell module.

[0025] Example 3 This embodiment provides a method for preparing a perovskite solar cell. The difference from Embodiment 2 is that in this embodiment, the volume ratio of DMSO, GVL, and 2-MeTHF is 1:3:1, while the other preparation methods and parameters remain the same as in Embodiment 1.

[0026] Example 4 This embodiment provides a method for preparing a perovskite solar cell. The difference from Embodiment 2 is that in this embodiment, the volume ratio of DMSO, GVL, and 2-MeTHF is 1:1:3, while the other preparation methods and parameters remain the same as in Embodiment 1.

[0027] Comparative Example This embodiment provides a method for preparing perovskite solar cells. The difference from Embodiment 1 is that, in this embodiment, the solvent for preparing the perovskite precursor solution does not include 2-MeTHF, but consists only of DMSO and GVL, with a volume ratio of DMSO to GVL of 1:4. The remaining preparation methods and parameters are consistent with those in Embodiment 1.

[0028] The perovskite solar cells prepared in Examples 2-4 and the comparative examples were characterized structurally and their performance was tested. Figure 1 , 2 As shown in the SEM images, perovskite films prepared with a precursor solution without 2-MeTHF (w / o 2-MeTHF) exhibit numerous pores. This is because GVL and DMSO have high boiling points, low saturated vapor pressures, and slow volatilization, and their strong interactions with perovskite molecules lead to the formation of numerous pores between the perovskite film and the substrate, affecting film quality and thus reducing device performance. However, the introduction of 2-MeTHF (w / 2-MeTHF) eliminates the pores and increases grain size. Figure 3As shown, the XRD results indicate that the perovskite film prepared in Example 1 has good crystal orientation. The PL spectrum also shows that the perovskite film prepared by the method in Example 1 has a low defect state density and high film quality. GVL was used as a moderately coordinated green solvent (MVCS), whose coordination ability is comparable to DMF but with low toxicity (LD50 > 2000 mg / kg), and is defined as a green solvent, which can completely replace traditional toxic solvents. Meanwhile, volatile 2-MeTHF, also defined as a green solvent, was selected as a non-coordinated green solvent (VNCS). On the one hand, mixing 2-MeTHF with GVL can change the boiling point and saturated vapor pressure of the mixed solvent, thereby increasing the evaporation rate of GVL. On the other hand, due to the dipole-dipole interaction between 2-MeTHF and GVL, the force of GVL on the perovskite is weakened, optimizing the crystallization kinetics. During the evaporation of GVL / DMSO, it is less likely to generate pores at the bottom of the perovskite film, resulting in a high-quality film. Meanwhile, the ternary solvent system evaporates quickly, and when used in conjunction with a high coating rate, the impact of the wet film evaporating freely in the air on the perovskite crystallization is reduced.

[0029] The photoelectric performance of the perovskite titanium solar cells in Examples 2-4 and the comparative examples was tested, and the test results are shown in Table 1: Table 1 Comparison of photoelectric performance of each embodiment and comparative example Samples Isc(A) Voc(V) FF(%) PCE (%) Comparative Example 0.543 47.76 74.8 19.08 Example 2 0.543 48.91 77.7 20.26 Example 3 0.547 47.68 75.3 19.33 Example 4 0.545 47.82 77.5 19.86 As shown in the table above, compared to perovskite devices prepared with a precursor solution without 2-MeTHF, the introduction of 2-MeTHF significantly improves device efficiency. This is mainly due to the fact that the introduction of 2-MeTHF optimizes crystallization kinetics, resulting in a denser perovskite film with fewer defects. Simultaneously, the solvent ratio was optimized, and further optimization was achieved, such as... Figure 5 As shown, compared with Examples 3 and 4, the solar cell prepared with the solvent ratio of DMSO:GVL:2-MeTHF=1:2:2 has higher performance, indicating that this solvent ratio can effectively suppress the generation of pores at the bottom of the thin film and improve device performance.

[0030] Example 5 This embodiment provides a method for fabricating a perovskite solar cell, used to fabricate a large-area perovskite solar cell of 600mm×1200mm, including the following steps: S1: Provide a 600mm×1200mm conductive substrate, perform P1 scribing on the conductive substrate, ultrasonically treat the P1 scribing conductive substrate in deionized water, detergent and isopropanol for 15min respectively, and dry the cleaned conductive substrate with nitrogen gas; form a hole transport layer on the conductive substrate. In this embodiment, the conductive substrate is an FTO glass substrate, and the hole transport layer is nickel oxide. S2: A perovskite precursor solution was prepared using dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol as solvents, wherein the volume ratio of DMSO, GVL, and 2-MeTHF was 1:2:2, and Cs was selected as the perovskite material. 0.05 FA 0.95 PbI3 at a concentration of 0.6 mol / L was used to prepare a perovskite film on the hole transport layer using a slit coating method at a coating speed of 16 mm / s. The perovskite film with a thickness of 400 nm was obtained by super vacuum drying (VCD) to assist solvent evaporation and perovskite crystallization, followed by heating on a hot stage at 130 °C for 20 min. S3: Forming an electron transport layer on the perovskite film, specifically including depositing a C layer on the perovskite film using a vacuum method. 60 Atomic deposition method was used in C 60 Depositing a layer of SnO2, in this embodiment, C 60 The thickness is 26nm, and the SnO2 thickness is 16nm; the electron transport layer is scribed with P2 lines. S4: A Cu layer is prepared on the electron transport layer by thermal evaporation as an electrode layer. The electrode layer is then scribed with P3 lines and encapsulated to obtain a perovskite solar cell module.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a precursor solution, characterized in that, Includes the following steps: Perovskite precursor solutions were prepared using dimethyl sulfoxide, 2-methyltetrahydrofuran and γ-valerol as solvents; The perovskite material is added to the solvent to form a perovskite precursor solution.

2. The method for preparing the precursor solution according to claim 1, characterized in that, The volume ratio of dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol in the solvent is 1:(1~3):(1~3).

3. The precursor solution preparation method according to claim 2, characterized in that, The concentration of the perovskite precursor solution is 0.6~1 mol / L.

4. A method for fabricating a perovskite solar cell, characterized in that, Includes the following steps: S1: Provide a conductive substrate, and deposit a hole transport layer on the conductive substrate; S2: A perovskite precursor solution is prepared using dimethyl sulfoxide, 2-methyltetrahydrofuran and γ-valerol as solvents, and a perovskite film is formed on the hole transport layer. S3: An electron transport layer is formed on the perovskite thin film; S4: An electrode layer is formed on the electron transport layer.

5. The method for preparing a perovskite solar cell according to claim 4, characterized in that, Before depositing the hole transport layer, the conductive substrate is scribing P1; before forming the electrode layer, the electron transport layer is scribing P2; after forming the electrode layer, the electrode layer is scribing P3.

6. The method for preparing a perovskite solar cell according to claim 4, characterized in that, In step S2, the volume ratio of dimethyl sulfoxide, 2-methyltetrahydrofuran, and γ-valerol in the perovskite precursor solution is 1:(1~3):(1~3).

7. The method for preparing a perovskite solar cell according to claim 4, characterized in that, The perovskite thin film formation process is as follows: The perovskite precursor solution is coated onto the hole transport layer at a coating rate of 15-25 mm / s, and then annealed at 130°C for 15-20 min to obtain a perovskite film.

8. The method for preparing a perovskite solar cell according to claim 4, characterized in that, The thickness of the perovskite film is 400 nm.

9. The method for preparing a perovskite solar cell according to claim 4, characterized in that, The electron transport layer comprises sequentially deposited C 60 Electron transport layer and SnO2 electron transport layer; the C 60 The thickness of the electron transport layer is 10-30 nm, and the thickness of the SnO2 electron transport layer is 10-30 nm.

10. The method for preparing a perovskite solar cell according to claim 4, characterized in that, The electrode layer is a copper electrode layer with a thickness of 100-200nm.

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