Manufacturing method of perovskite light absorption layer

Abstract

The invention relates to a manufacturing method of a perovskite light absorption layer, which comprises the following steps: preparing a perovskite precursor solution, performing primary coating and secondary coating, coating 0.05-0.25 g / ml CPZPY solution on the surface of a perovskite thin film by adopting a slit coating machine in the secondary coating, and performing flash evaporation on the CPZPY film to obtain the passivated perovskite thin film. According to the manufacturing method, lone pair electrons, which do not participate in conjugation, of CPZPY can interact with uncoordinated Pb < 2 + >, so that hole defects such as insufficient atom coordination, unsaturated bonds and dangling bonds on the surface of the perovskite thin film are passivated. Chloride ions can also be provided, the interaction between FA and iodide ions can be enhanced, and the stability of the FAPbI3 perovskite structure can be improved. Open-circuit voltage and short-circuit current density are slightly increased, filling factors are obviously increased, photoelectric conversion efficiency is improved, and it can be indicated that non-radiative recombination at the interface in a perovskite solar cell device is weakened, and the passivation effect is obvious.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for manufacturing a perovskite light-absorbing layer. Background Technology

[0002] Organic-inorganic metal halide perovskite hybrid materials have shown great application potential in the field of photovoltaic technology, with their photoelectric conversion efficiency now exceeding 26.8%. Compared with traditional materials, perovskites have excellent photoelectric properties such as high absorption coefficient, long carrier diffusion length and low trap density. Among them, formamidinium perovskite (FAPbI3) has become a widely studied material due to its ideal optical band gap and good thermal stability.

[0003] However, larger formamidin ions (FA) + The optically active α-FAPbI3 phase readily transforms into the non-optically active δ-FAPbI3 phase at room temperature, a common problem encountered in the fabrication of high-efficiency formamidinium perovskite solar cells. Currently, methylamine hydrochloride (MACl)-assisted crystallization of the δ-FAPbI3 phase is a simple and effective common method; however, the addition of MACl also introduces several challenges. The most obvious is that the addition of MACl leads to non-stoichiometric problems in the perovskite film, resulting in defect vacancies. This is because, during the annealing process of the perovskite film, the asynchronous volatilization of methylamine cations and chloride ions leads to insufficient coordination of local film atoms, forming vacancies. Halogen ion vacancies, due to their lower defect formation energy and higher carrier mobility, are more likely to form in large quantities. These vacancy defects act as non-radiative recombination centers, reducing the performance of perovskite solar cells, especially hindering the fabrication of large-area, high-quality perovskite films and ensuring film stability. This affects the repeatability and long-term stability of perovskite solar modules, limiting their commercial application.

[0004] Therefore, the present invention provides a new additive formulation to solve the above problems. Summary of the Invention

[0005] The main objective of this invention is to provide a method for manufacturing a perovskite light-absorbing layer, which enables the light-absorbing layer to have higher open-circuit voltage, short-circuit current density and fill factor after passivation, thereby improving the stability of the perovskite structure.

[0006] This invention achieves the above objective through the following technical solution: a method for manufacturing a perovskite light-absorbing layer, comprising the following steps: S1. Prepare the perovskite precursor solution: according to FA 0.95 Cs 0.05The perovskite precursor raw material with a molar concentration of 1.0~1.2 mol / L was prepared by mixing PbI3 in a 6:1 volume ratio of DMF / NMP mixed solvent, and 10~12.5 mol% MACl was added. The mixture was stirred until there was no precipitate, filtered, and the perovskite precursor solution was obtained. S2. One-time coating: The coating liquid is coated onto the substrate using a slot coater to form a perovskite wet film. The perovskite wet film is then subjected to a VCD flash annealing process to obtain a perovskite thin film. S3. Secondary coating: A 0.05-0.25 g / ml CPZPY chloroform solution is coated onto the surface of the perovskite film using a slot coater. The CPZPY film is then subjected to VCD flash annealing to obtain a passivated perovskite film.

[0007] Specifically, in step S1, a filter head with a 0.22µm pore size and PTFE material is used for filtration.

[0008] Specifically, in step S2, the coating speed of the slit coater is 30~50mm / s, and the distance between the substrate and the lip of the slit coater is 100~120um.

[0009] Furthermore, in step S2, the flash evaporation temperature is 140-200℃, the pressure is 5-10Pa, the flash evaporation time is 10-20s, and the annealing time is 30-60min.

[0010] Specifically, in step S3, the coating speed of the slot coater is 60~100mm / s, and the distance between the perovskite film and the lip of the slot coater is 100~120um.

[0011] Specifically, the flash evaporation pressure in step S3 is 5~10 Pa, the flash evaporation time is 8~15 s, and the annealing time is 5~8 min.

[0012] The beneficial effects of the technical solution of this invention are: 1. CPZPY has a small molecular size and high flexibility, which avoids large steric hindrance. It can be attached to the film surface through a twisted structure, improving stability. Its unconjugated lone pair electrons can interact with uncoordinated Pb. 2+ The interaction between CPZPY and FAPbI3 perovskite film surfaces passesivates defects such as insufficient atomic coordination, unsaturated bonds, and dangling bonds. Compared with PZPY, CPZPY exhibits stronger polarity and interacts more readily with the film surface. It can also provide chloride ions, which can enhance the interaction between FA and iodide ions, thus helping to improve the stability of the FAPbI3 perovskite structure. 2. The efficiency of the CPZPY passivated device is better than that of the blank example. The open-circuit voltage and short-circuit current density are slightly increased, the fill factor is significantly increased, and the photoelectric conversion efficiency is increased. This indicates that the non-radiative recombination at the interface of the perovskite solar cell device is weakened and the passivation effect is obvious. Attached Figure Description

[0013] Figure 1 This is a SEM image of the perovskite film before passivation treatment; Figure 2 SEM images of the perovskite film after CPZPY passivation treatment; Figure 3 SEM images of perovskite films after PZPY passivation treatment; Figure 4 This is a comparison chart of IV test results for perovskite solar devices before passivation, after CPZPY passivation, and after PZPY passivation. Detailed Implementation

[0014] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0015] Example: A method for manufacturing a perovskite light-absorbing layer includes the following steps: S1. Preparation of perovskite precursor solution: Weigh out 14.71~17.64g of FAI (formamidinium hydroiodide), 1.17~1.404g of CsI (cesium iodide), 41.49~49.79g of PbI2 (lead iodide), and 0.6075~0.7594g of MACl (methylamine hydrochloride) sequentially. Disperse these components in 60mL of DMF (N,N-dimethylformamide) and 10mL of NMP (N-methylpyrrolidone) solvent, and stir until homogeneous and free of precipitate. Filter the solution using a 0.22µm PTFE filter to obtain the perovskite precursor solution.

[0016] The perovskite precursor solution contains the film-forming solid components of perovskite. To ensure better mixing, these solid components need to be dispersed in the solution first to make the solute homogeneous and remove impurities. Because the substances in the perovskite precursor solution have purity issues, impurities will form, which will disrupt the homogeneity of the coating solution and thus affect the quality of the perovskite film. Therefore, a filtration is required here to trap larger molecular weight impurities in the PTFE filter head.

[0017] S2. Single Coating: The coating liquid is applied to the substrate using a slot coater at a speed of 30-50 mm / s. The distance between the substrate and the lip of the slot coater is 100-120 μm, forming a perovskite wet film. This wet film is then subjected to a VCD flash annealing process to obtain a perovskite thin film. The flash annealing temperature is 140-200℃, the pressure is 5-10 Pa, the flash annealing time is 10-20 s, and the annealing time is 30-60 min.

[0018] The main purpose of a single coating is to adhere the perovskite solution to the substrate and complete the curing process in advance. The passivation solution (CPZPY solution) must not be mixed with the perovskite solution during coating, otherwise it will significantly affect the Oswald ripening process during the nucleation and crystallization of the perovskite film, which is detrimental to crystal growth. Therefore, after coating, the wet perovskite film needs to be annealed to dryness before passivation treatment.

[0019] S3. Secondary Coating: A 0.05-0.25 g / ml CPZPY chloroform (CHCl3) solution is coated onto the surface of the perovskite film using a slot coater. The CPZPY film is then subjected to VCD flash annealing to obtain a passivated perovskite film. The coating speed of the slot coater is 60-100 mm / s, and the lip distance between the perovskite film and the slot coater is 100-120 μm. The flash pressure is 5-10 Pa, the flash time is 8-15 s, and the annealing time is 5-8 min.

[0020] The molecular structure of CPZPY (5-chloro-2-(1H-pyrazol-1-yl)pyridine) is as follows:

[0021] This demonstrates that CPZPY has a small molecular size and high flexibility, avoiding significant steric hindrance. It can adhere to film surfaces through a twisted structure, enhancing stability. Its unconjugated lone pair electrons can interact with uncoordinated Pb. 2+ The interaction between CPZPY and FAPbI3 perovskite films passesivates defects such as insufficient atomic coordination, unsaturated bonds, and dangling bonds on the film surface. Compared with PZPY, CPZPY exhibits stronger polarity and interacts more readily with the film surface. It can also provide chloride ions, which can enhance the interaction between FA and iodide ions, thus contributing to the improvement of the stability of the FAPbI3 perovskite structure.

[0022] Meanwhile, CPZPY exhibits excellent chemical and thermal stability and will not decompose during subsequent perovskite solar cell fabrication and encapsulation processes.

[0023] A comparative experiment was conducted on a perovskite solar cell device manufactured according to the steps of the embodiment (designated CPZPY in the figure), a perovskite solar cell device without passivation treatment (designated control in the figure), and a perovskite solar cell device passivated with PZPY (designated PZPY in the figure). The results are shown in [Figure Number]. Figures 1-4 .

[0024] Depend on Figures 1 to 3 It can be seen that, under the same SEM magnification ratio, the crystalline structure of the perovskite film treated with CPZPY is comparable to that of the control, while the perovskite film treated with PZPY has a fragmented structure, which means that CPZPY only has a surface passivation effect.

[0025] Depend on Figure 4 As can be seen from the IV test results, the efficiency of the CPZPY passivated device is better than that of the blank example (control). The open-circuit voltage and short-circuit current density are slightly increased, the fill factor is significantly increased, and the photoelectric conversion efficiency is increased. This indicates that the non-radiative recombination at the interface of the perovskite solar cell device is weakened and the passivation effect is obvious.

[0026] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing a perovskite light-absorbing layer, characterized in that... The steps include: S1. Prepare the perovskite precursor solution: according to FA 0.95 Cs 0.05 The perovskite precursor raw material with a molar concentration of 1.0~1.2 mol / L was prepared by mixing PbI3 in a 6:1 volume ratio of DMF / NMP mixed solvent, and 10~12.5 mol% MACl was added. The mixture was stirred until there was no precipitate, filtered, and the perovskite precursor solution was obtained. S2. One-time coating: The coating liquid is coated onto the substrate using a slot coater to form a perovskite wet film. The perovskite wet film is then subjected to a VCD flash annealing process to obtain a perovskite thin film. S3. Secondary coating: A 0.05-0.25 g / ml CPZPY chloroform solution is coated onto the surface of the perovskite film using a slot coater. The CPZPY film is then subjected to VCD flash annealing to obtain a passivated perovskite film.

2. The method for manufacturing the perovskite light-absorbing layer according to claim 1, characterized in that: In step S1, a filter head with a 0.22µm pore size and PTFE material is used for filtration.

3. The method for manufacturing the perovskite light-absorbing layer according to claim 1, characterized in that: In step S2, the coating speed of the slit coater is 30~50mm / s, and the distance between the substrate and the lip of the slit coater is 100~120um.

4. The method of using the additive according to claim 3, characterized in that: The flash evaporation temperature in step S2 is 140-200℃, the pressure is 5-10Pa, the flash evaporation time is 10-20s, and the annealing time is 30-60min.

5. The method of using the additive according to claim 1, characterized in that: In step S3, the coating speed of the slot coater is 60~100mm / s, and the distance between the perovskite film and the lip of the slot coater is 100~120um.

6. The method of using the additive according to claim 1, characterized in that: The flash evaporation pressure in step S3 is 5~10 Pa, the flash evaporation time is 8~15 s, and the annealing time is 5~8 min.

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