Perovskite precursor solution, perovskite light absorption layer, preparation method of perovskite light absorption layer and photoelectric device

Abstract

The invention relates to the technical field of perovskite preparation, in particular to a perovskite precursor solution, a perovskite light absorption layer, a preparation method of the perovskite light absorption layer and a photoelectric device. The perovskite precursor solution comprises lead halide, an organic ammonium salt, an organic solvent and a perovskite precursor solution additive; the perovskite precursor solution additive comprises an organic sulfur compound containing a thiazole ring and a sulfoxide group. An organic sulfur compound containing a thiazole ring and a sulfoxide group is introduced into the perovskite precursor solution as an additive, so that the stability of the precursor solution can be improved. The additive can effectively regulate and control crystal growth behaviors in a precursor solution and inhibit agglomeration of excessive lead halide and formation of large-size crystal grains, so that a uniform and compact perovskite light absorption layer can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite preparation, and particularly relates to a perovskite precursor solution, a perovskite light-absorbing layer, a preparation method thereof and a photoelectric device. BACKGROUND

[0002] Organic-inorganic hybrid perovskite materials (general formula is ABX3, wherein A is an organic cation such as methylammonium ion (MA + ), formamidinium ion (FA + ), B is a metal cation such as Pb 2+ , and X is a halide anion such as I - , Br - ) have caused a revolutionary research boom in the field of optoelectronics, especially in solar cells, due to their excellent photoelectric properties such as high absorption coefficient, long carrier diffusion length, adjustable band gap and low solution preparation cost.

[0003] Solution method spin coating technology is the mainstream method for laboratory research and future large-scale printing preparation of perovskite thin films. The core of this technology is to prepare a uniform and stable perovskite precursor solution, which is usually composed of a lead source (such as lead iodide, PbI2) and an organic ammonium salt (such as methylamine iodide, MAI or formamidinium iodide, FAI) dissolved in a polar aprotic solvent (such as N, N-dimethylformamide, DMF; dimethyl sulfoxide, DMSO).

[0004] However, the commercialization process of perovskite technology still faces many challenges, including not only the long-term running stability of the final device under light, heat and electric field, but also a problem that is equally important but severely underestimated in the context of industrialization: the perovskite precursor solution has poor stability and cannot be used after being placed for a period of time, which also seriously affects the performance of the device.

[0005] Therefore, the prior art needs to be improved. SUMMARY

[0006] The present application provides a perovskite precursor solution, a perovskite light-absorbing layer, a preparation method thereof and a photoelectric device, and aims to solve the problem of poor stability of the perovskite precursor solution.

[0007] In a first aspect, the present application provides a perovskite precursor solution, comprising a lead halide, an organic ammonium salt, an organic solvent and a perovskite precursor solution additive; the perovskite precursor solution additive comprises an organic sulfur compound containing a thiazole ring and a sulfoxide group.

[0008] Optionally, the organic sulfur compound containing a thiazole ring and a sulfoxide group is 2-methylisothiazolidine-1,1-dioxide (NMDI).

[0009] Optionally, the mass of the 2-methylisothiazolidin-1,1-dioxide is 0.2-2.0% of the total mass of the perovskite precursor solution.

[0010] Optionally, the perovskite precursor solution further includes CsI.

[0011] Optionally, the mass of CsI is 1-10% of the total mass of the perovskite precursor solution.

[0012] Optionally, the lead halide is PbI2, PbCl2, or PbBr2; The organic ammonium salt is HC(NH2)2I or CH6IH; The mass ratio of lead halide, organic ammonium salt, and perovskite precursor solution additive is 450-500: 130-170: 3-30. The volume-to-mass ratio of the organic solvent to the lead halide is 800-1000 μL: 450-500 mg; The organic solvent is a mixed solution of N,N-dimethylformamide and 1,3-dimethyl-2-imidazolinone in a volume ratio of 6-8:0.5-2.

[0013] In a second aspect, the present invention provides a perovskite light-absorbing layer prepared from the perovskite precursor solution.

[0014] In a third aspect, the present invention provides a method for preparing a perovskite light-absorbing layer, comprising taking a substrate, placing the perovskite precursor solution on the substrate, and then annealing to obtain the perovskite light-absorbing layer.

[0015] Optionally, the perovskite precursor solution is applied to the substrate by a blade coating method at a rate of 3-10 mm / s; the annealing includes annealing at 75°C for 3-15 min and annealing at 130°C for 5-25 min.

[0016] In a fourth aspect, the present invention provides an optoelectronic device comprising the aforementioned perovskite light-absorbing layer.

[0017] Beneficial effects: Introducing an organic sulfur compound containing a thiazole ring and a sulfoxide group as an additive into the perovskite precursor solution of the present invention can improve the stability of the precursor solution. This additive can effectively regulate crystal growth behavior in the precursor solution, inhibit the agglomeration of excess lead halide and the formation of large-sized grains, thereby obtaining a uniform and dense perovskite light-absorbing layer. Attached Figure Description

[0018] Figure 1 The XRD patterns are for different NMDI concentrations, with the left image representing the fresh solution and the right image representing the aged solution.

[0019] Figure 2 The XRD patterns are for different NMDI concentrations over a small range, with the left image showing the fresh solution and the right image showing the aged solution.

[0020] Figure 3 The figures show the PCE of perovskite devices with different NMDI concentrations, with the left figure showing the fresh solution and the right figure showing the aged solution.

[0021] Figure 4 SEM image of the perovskite light-absorbing layer without NMDI doping.

[0022] Figure 5 SEM image of the perovskite light-absorbing layer after NMDI doping. Detailed Implementation

[0023] This invention provides a perovskite precursor solution, a perovskite light-absorbing layer, a method for preparing the same, and an optoelectronic device. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] Due to the poor stability of existing perovskite precursor solutions, they become unusable after being left for a period of time, severely affecting device performance.

[0025] Based on this, this embodiment provides a perovskite precursor solution, comprising lead halide, an organic ammonium salt, an organic solvent, and a perovskite precursor solution additive; the perovskite precursor solution additive comprises an organic sulfur compound containing a thiazole ring and a sulfoxide group.

[0026] This embodiment introduces an organic sulfur compound containing a thiazole ring and a sulfoxide group into the precursor solution. This compound can form stable coordination bonds with metal ions in the perovskite precursor solution, effectively inhibiting the spontaneous aggregation and crystallization of lead halides, such as lead iodide. Simultaneously, the thiazole ring and sulfoxide group in this compound have antioxidant properties, reducing the oxidation rate of iodide ions and delaying discoloration and degradation of the precursor solution. Furthermore, the sulfur-containing compound can adsorb onto the surface of PbI colloidal particles, preventing further colloid growth and maintaining a small and uniform particle size in the solution. Through these multiple effects, the compound significantly improves the storage stability of the perovskite precursor solution and obtains a uniform and dense perovskite light-absorbing layer during film formation, thereby reducing defects and the formation of the δ phase and improving the long-term stability of the device.

[0027] In one embodiment, the organosulfur compound containing a thiazole ring and a sulfoxide group is 2-methylisothiazolidin-1,1-dioxide (NMDI).

[0028] In some embodiments, the mass of the 2-methylisothiazolidin-1,1-dioxide is 0.2-2.0% of the total mass of the perovskite precursor solution. Extensive experiments have shown that within this range, the additive 2-methylisothiazolidin-1,1-dioxide most effectively improves the quality of the perovskite film and the stability of the device without introducing negative effects. Below 0.2%, the effect is not significant, while above 2.0% may produce adverse effects.

[0029] In one embodiment, the perovskite precursor solution further includes CsI. The purpose of adding CsI in this embodiment is to alloy the components of the perovskite material. It typically partially replaces conventional organic cations (such as formamidinium, FA). + Or ammonium methylamine, MA + This process forms mixed cationic perovskites, thereby improving thermal stability and phase stability. It can also regulate the crystallization process and improve film quality. (Cs) + The introduction of [a specific substance] can increase the nucleation barrier in the crystallization process, making the crystallization process slower and more controllable. This helps to obtain perovskite films with larger grains, more uniform size, and more complete coverage.

[0030] In some embodiments, the mass of CsI is 1-10% of the total mass of the perovskite precursor solution. When the amount of CsI added is less than 1%, its concentration may be insufficient to produce the desired technical effects. For example, in perovskite solar cells, CsI is typically added to improve the thermal and phase stability of the device and to adjust the band gap. If the amount added is too small, these improvements will be negligible and will not achieve the purpose of the invention. When the amount added exceeds 10%, it may introduce negative effects. For example, excessive CsI may disrupt the crystallinity of the perovskite material, leading to a decrease in film quality, the introduction of defects, and consequently reducing the photoelectric conversion efficiency or long-term stability of the cell. An appropriate amount of CsI is the key balance range for achieving performance improvements (stability, efficiency, etc.) while avoiding negative effects. Any embodiment falling within this range can reliably reproduce the excellent effects of the invention.

[0031] In some embodiments, the lead halide is PbI2, PbCl2, or PbBr2.

[0032] In some embodiments, the organic ammonium salt is HC(NH2)2I or CH6IH.

[0033] In some embodiments, the mass ratio of lead halide, organic ammonium salt, and perovskite precursor solution additive is 450-500:130-170:3-30.

[0034] In some embodiments, the volume-to-mass ratio of the organic solvent to the lead halide is 800-1000 μL: 450-500 mg.

[0035] In some embodiments, the organic solvent is a mixed solution of N,N-dimethylformamide and 1,3-dimethyl-2-imidazolinone in a volume ratio of 6-8:0.5-2.

[0036] This embodiment also provides a perovskite light-absorbing layer, which is prepared from the perovskite precursor solution.

[0037] This embodiment also provides a method for preparing a perovskite light-absorbing layer, wherein a substrate is taken, the perovskite precursor solution is placed on the substrate, and then annealed to obtain the perovskite light-absorbing layer.

[0038] In some embodiments, the pre-perovskite precursor solution is applied to the substrate by a blade coating method at a rate of 3-10 mm / s; the annealing includes annealing at a temperature of 75-125°C for 3-15 min and annealing at a temperature of 130-180°C for 5-25 min.

[0039] This embodiment also provides an optoelectronic device, including the perovskite light-absorbing layer.

[0040] It should be noted that the coating of the perovskite light-absorbing layer is completed in a glove box, and after coating, it needs to undergo flash evaporation, which is completed by evaporating air in a vacuum flash evaporator.

[0041] The substrate is an ITO substrate with an electron transport layer spin-coated, and the fabrication process includes: The patterned ITO substrate was sequentially cleaned with an ultrasonic bath using diluted detergent, deionized water, and IPA for 20 minutes; after drying, the cleaned ITO substrate was subjected to ultraviolet ozone treatment for 30 minutes to obtain a clean ITO substrate. Me-4PACz solution (0.4 mg / mL dissolved in ethanol) was then spin-coated onto the ITO substrate at 3000 rpm for 30 seconds, followed by annealing at 100 °C for 10 minutes.

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] Example 1 1. The perovskite precursor solution comprises the following steps: adding 472 mg PbI2, 154.8 mg FAI, 26.0 mg CsI, and 0.7 mg NMDI to a mixed solution of 800 μL DMF and 100 μL DMI and shaking. In this embodiment, the concentration of NMDI is 0.5%.

[0044] 2. Fabrication of optoelectronic devices, including the following steps: 1) The patterned ITO substrate was sequentially cleaned for 20 minutes using an ultrasonic bath with diluted detergent, deionized water, and IPA. After drying, the cleaned ITO substrate was subjected to ultraviolet ozone treatment for 30 minutes to obtain a clean ITO substrate.

[0045] 2) Me-4PACz solution (0.4 mg / mL dissolved in ethanol) was spin-coated onto a clean ITO substrate at 3000 rpm for 30 seconds, followed by annealing at 100 °C for 10 minutes.

[0046] 3) First, clean the glove box with dry air for about 1 hour. Then, take 20 μL of the precursor and drop it into the gap between the doctor blade and the substrate. Spread it at a speed of 6 mm / s. After the spread is completed, put the sample into a vacuum flash evaporator to remove air. After the flash evaporation is completed, pre-anneal the obtained sample at 105°C for more than 5 minutes on a hot stage. Then, raise the temperature of the hot stage to 150°C and anneal for 10 minutes to obtain the perovskite light-absorbing layer.

[0047] 4) A PC61BM solution (10 mg / mL dissolved in chlorobenzene) was spin-coated onto the perovskite light-absorbing layer at 3000 rpm for 40 s. A 10 nm C60, a 10 nm SnO2, and a 90 nm silver electrode were deposited by thermal evaporation at an evaporation rate of 0.1–0.5 Å / s.

[0048] Example 2 The difference between this embodiment and Embodiment 1 is that the NMDI in this embodiment is 1.4 mg, and the concentration of NMDI in this embodiment is 1.0%.

[0049] Example 3 The difference between this embodiment and Embodiment 1 is that the NMDI in this embodiment is 2.8 mg, and the concentration of NMDI in this embodiment is 2.0%.

[0050] Comparative Example 1 The difference between this comparative example and Example 1 is that the NMDI content in this example is 0g.

[0051] Powder diffraction was performed on the perovskite light-absorbing layers of Examples 1, 2, 3, and Comparative Example 1, and the results are as follows: Figure 1 , 2 As shown. Figure 1 XRD patterns of different NMDI concentrations are shown, with the left image representing the fresh solution and the right image representing the aged solution. The left image shows that the addition of 0.05% NMDI resulted in the lowest PbI2 peak intensity (12.7°), indicating that reducing PbI2 concentration improves device stability. The right image (CT) represents the aged solution without NMDI, demonstrating that adding NMDI to the aged solution effectively suppresses the formation of the δ phase (11.6°).

[0052] Figure 2The XRD patterns for different NMDI concentrations are shown in the left figure, which represents the fresh solution, and the right figure represents the aged solution. The left figure clearly shows that the PbI2 peak intensity is lowest after adding 0.05% NMDI. The right figure also clearly shows that adding NMDI effectively suppresses the formation of the δ phase (11.6°).

[0053] The photoelectric conversion efficiency of the perovskite devices in Examples 1, 2, 3 and Comparative Example 1 was tested, and the results are as follows: Figure 3 As shown. Figure 3 The figure shows the PCE of perovskite devices with different NMDI concentrations. The left figure represents the fresh solution, and the right figure represents the aged solution. The left figure shows that adding 0.05% NMDI to the fresh perovskite solution improves the performance of the perovskite devices; further increasing the concentration actually reduces performance. The right figure shows that after 720 hours of aging in the perovskite solution, the undoped perovskite device performs extremely poorly, while adding 0.05% NMDI results in a PCE of 11.5%. Therefore, it can be concluded that NMDI helps alleviate the aging problem of perovskite precursor solutions.

[0054] Figure 4 SEM image of the perovskite light-absorbing layer without NMDI doping. Figure 5 SEM image of the perovskite light-absorbing layer after NMDI doping. Figure 4 The image on the left is a 30,000x SEM of a thin film without NMDI doping, and the image on the right is a 10,000x SEM of a thin film without NMDI doping. Figure 5 The image on the left is a 30,000x SEM image of a thin film doped with 0.05% perovskite solution, and the image on the right is a 10,000x SEM image of a thin film doped with 0.05% perovskite solution. It can be seen that doping with 0.05% NMDI can effectively reduce the size of lead iodide on the surface of the perovskite light-absorbing layer, proving that NMDI interacts with PbI2, improves the quality of the perovskite light-absorbing layer, and enhances device performance.

[0055] Scanning electron microscopy (SEM) characterization results showed that the introduction of the additive significantly reduced the size of lead iodide particles in the film, improving the uniformity and density of the film. X-ray diffraction (XRD) results showed that after 720 hours of storage at room temperature, a distinct δ phase appeared in the perovskite absorbing layer without the additive, while no δ phase was detected in the perovskite absorbing layer prepared using the precursor solution of this invention, maintaining excellent crystal phase stability.

[0056] In summary, this invention adds specific organic sulfur compounds to the perovskite precursor solution. These compounds form stable coordination bonds with metal ions in the perovskite precursor solution, effectively inhibiting the spontaneous aggregation and crystallization of lead halides (lead iodide). Simultaneously, the thiazole ring and sulfoxide groups in these compounds have antioxidant properties, reducing the oxidation rate of iodide ions and delaying discoloration and degradation of the precursor solution. Furthermore, the sulfur-containing compounds can adsorb onto the surface of PbI colloidal particles, preventing further colloid growth and maintaining a small and uniform particle size in the solution. Through these multiple effects, the compound significantly improves the storage stability of the perovskite precursor solution and obtains a uniform and dense perovskite light-absorbing layer during film formation, thereby reducing defects and the formation of the δ phase and improving the long-term stability of the device.

[0057] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A perovskite precursor solution, characterized in that, It includes lead halides, organic ammonium salts, organic solvents, and perovskite precursor solution additives; the perovskite precursor solution additives include organic sulfur compounds containing thiazole rings and sulfoxide groups.

2. The perovskite precursor solution according to claim 1, characterized in that, The organosulfur compound containing a thiazole ring and a sulfoxide group is 2-methylisothiazolidin-1,1-dioxide.

3. The perovskite precursor solution according to claim 2, characterized in that, The mass of the 2-methylisothiazolidin-1,1-dioxide is 0.2-2.0% of the total mass of the perovskite precursor solution.

4. The perovskite precursor solution according to claim 1, characterized in that, The perovskite precursor solution also includes CsI.

5. The perovskite precursor solution according to claim 4, characterized in that, The mass of CsI is 1-10% of the total mass of the perovskite precursor solution.

6. The perovskite precursor solution according to claim 1, characterized in that, The lead halide is PbI2, PbCl2, or PbBr2; The organic ammonium salt is HC(NH2)2I or CH6IH; The mass ratio of lead halide, organic ammonium salt, and perovskite precursor solution additive is 450-500: 130-170: 3-30. The volume-to-mass ratio of the organic solvent to the lead halide is 800-1000 μL: 450-500 mg; The organic solvent is a mixed solution of N,N-dimethylformamide and 1,3-dimethyl-2-imidazolinone in a volume ratio of 6-8:0.5-2.

7. A perovskite light-absorbing layer, characterized in that, It is prepared from the perovskite precursor solution according to any one of claims 1-6.

8. A method for preparing a perovskite light-absorbing layer, characterized in that, Take a substrate, place the perovskite precursor solution of any one of claims 1-6 on the substrate, and then anneal it to obtain the perovskite light-absorbing layer.

9. The method for preparing a perovskite light-absorbing layer according to claim 8, characterized in that, The perovskite precursor solution is applied to the substrate by a blade coating method at a rate of 3-10 mm / s; the annealing includes annealing at a temperature of 75-125 °C for 3-15 min and annealing at a temperature of 130-180 °C for 5-25 min.

10. An optoelectronic device, characterized in that, Includes the perovskite light-absorbing layer as described in claim 7.

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