Hybrid self-assembly monomolecular layer construction method for improving stability of NiOx interface of semitransparent perovskite solar cell

Abstract

The invention discloses a hybrid self-assembly monomolecular layer construction method for improving the stability of a NiOx interface of a semitransparent perovskite solar cell, and belongs to the technical field of perovskite solar cells. The invention relates to a method for constructing a mixed self-assembled monomolecular layer by co-assembling 1, 2, 4-benzene tricarboxylic acid and [4-(3, 6-dimethyl-9H-carbazole-9-yl) butyl] phosphoric acid, which is used for enhancing the stability and wettability of a nickel oxide interface in a perovskite solar cell. The constructed mixed SAM effectively relieves the damage of traditional polar solvent scouring to a monomolecular layer, and reduces the defects of interface nano holes and grain boundaries, thereby obtaining a compact and continuous ultrathin perovskite film. The semitransparent perovskite solar device prepared by the method shows lower defect density, better interface coupling and remarkably improved photoelectric conversion efficiency and long-term stability.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically, it relates to a hybrid self-assembled monolayer construction method for improving the NiOx interface stability of semi-transparent perovskite solar cells. Background Technology

[0002] Perovskite solar cells have become a research hotspot in the photovoltaic field due to their excellent photoelectric conversion efficiency and relatively low manufacturing costs. Among them, inverted (pin) structure devices show broad application prospects in flexible, semi-transparent, and tandem cells due to their simple process, low-temperature fabrication, and good stability. Nickel oxide (NiOx), as a common inorganic hole transport material, possesses high optical transmittance, suitable band structure, and excellent chemical stability, and is widely used in inverted perovskite cells and all-perovskite tandem devices. However, the ubiquitous oxygen vacancies and uncoordinated Ni on the NiOx surface... 2+ Defect states, such as perovskite precursors, are prone to react with the perovskite precursors, inducing nonradiative recombination at the interface, which leads to a decrease in the open-circuit voltage and a decline in long-term stability of the device.

[0003] Furthermore, to improve the applicability of perovskite solar cells in building-integrated photovoltaics (BIPV) and other scenarios, semi-transparent devices need to maintain high photoelectric conversion efficiency while possessing good visible light transmittance. Therefore, the thickness of the perovskite absorber layer typically needs to be reduced to below 200 nm, and a low-concentration precursor solution is used to minimize light absorption loss. However, these ultrathin perovskite films face two major challenges during deposition: First, commonly used self-assembled monolayer materials such as Me-4PACz (Me-4PACz, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate) are hydrophobic and have poor compatibility with highly polar perovskite precursor solvents (such as DMF and DMSO), which can easily lead to uneven wetting at the interface, causing local dewetting, rearrangement of the self-assembled layer, and even partial detachment, resulting in nanopores, discontinuous crystallization, and increased defect state density at the interface. Second, low-concentration precursors have less solvent and a narrow crystallization window during film formation, which can easily lead to a decrease in perovskite grain size, an increase in grain boundaries, and a decrease in film compactness, thereby reducing carrier transport efficiency and exacerbating interfacial recombination.

[0004] In summary, the poor wettability, numerous defect states, and difficulty in controlling the crystallization quality of ultrathin perovskite films at the NiOx / self-assembled monolayer interface severely restrict the development of high-efficiency, high-stability, semi-transparent perovskite solar cells. These problems urgently need to be addressed to meet the higher demands of the perovskite solar cell technology field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hybrid self-assembled monolayer construction method for improving the NiOx interface stability of semi-transparent perovskite solar cells.

[0006] The objective of this invention can be achieved through the following technical solutions: A hybrid self-assembled monolayer construction method for improving NiOx interface stability in semi-transparent perovskite solar cells includes the following steps: S1. The ITO conductive glass substrate is ultrasonically cleaned sequentially with glass cleaner, deionized water, acetone and ethanol. After cleaning, it is dried with nitrogen to obtain clean ITO glass. S2. Add nickel oxide powder to deionized water and ultrasonically disperse for 2-5 minutes to obtain a uniform NiOx dispersion. Then spin-coat the NiOx dispersion onto a clean ITO glass. After spin-coating, perform annealing to form a uniform NiOx film. S3. Add 1,2,4-benzenetricarboxylic acid (TMLA) and Me-4PACz to isopropanol, dissolve them under magnetic stirring at room temperature, prepare a solution, spin coat it onto the surface of NiOx film, and after spin coating for 30-60s, perform annealing treatment to obtain a substrate with surface covered by mixed SAM. S4. Add methylammonium chloride, lead iodide, lead bromide, cesium iodide, formamidinium hydroiodate, and methylammonium bromide to a solvent to prepare Cs. 0.05 (FA 0.95 MA 0.05 ) 0.95 Pb(I 0.95 Br 0.05 )3. Precursor fluids; S5. Spin-coat the precursor liquid onto the substrate covered with mixed SAM using a two-step spin-coating method. First, spin-coat slowly for 8-10 seconds, then spin-coat quickly for 30-50 seconds. In the last 5-10 seconds of spin-coating, add chlorobenzene anti-solvent for solvent extraction. Finally, perform annealing to form a well-crystallized perovskite film. S6. Prepare solutions of phenylethyl ammonium iodide (PEAI), isomethyl [6,6]-phenyl-C61-butyrate (PCBM), and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), and spin-coat them sequentially onto the surface of the perovskite film for 30 seconds to form an electron transport layer / passivation layer structure. Finally, use thermal evaporation to sequentially deposit a silver film and a molybdenum trioxide film to complete the self-assembled monolayer construction and obtain a semi-transparent perovskite film.

[0007] Preferably, the spin coating speed in steps S2 and S3 is 3000-5000 rpm.

[0008] Preferably, the annealing temperature in step S2 is 100-150℃ and the time is 15-30 min.

[0009] Preferably, in step S3, the concentration of 1,2,4-benzenetricarboxylic acid in the prepared solution is 0.1-0.2 mg / mL, and the concentration of Me-4PACz is 0.5-1 mg / mL.

[0010] Preferably, the annealing temperature in step S3 is 100-120℃ and the time is 10-20 min.

[0011] Preferably, the solvent in step S4 is a mixed solvent of N,N-dimethylformamide and N-methylpyrrolidone, with a volume ratio of 7:1.

[0012] Preferably, the concentration of the precursor fluid in step S4 is 0.5 mol / L.

[0013] Preferably, in step S5, the rotation speed for slow spin coating is 800-1000 rpm; and the rotation speed for fast spin coating is 4000-5000 rpm.

[0014] Preferably, the annealing temperature in step S5 is 100-120℃ and the time is 20-40 min.

[0015] Preferably, the spin coating speed in step S6 is 3000-6000 rpm.

[0016] Preferably, in step S6, the concentration of the phenylethyl ammonium iodide solution is 1-5 mg / mL; the concentration of the [6,6]-phenyl-C61-butyric acid isomethyl ester solution is 15-20 mg / mL; and the concentration of the 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline solution is 0.5-1 mg / mL.

[0017] The mechanism of the construction method of this invention is as follows: 1. First, a TMLA molecule containing three carboxyl groups is introduced and co-assembled with the commonly used Me-4PACz molecule. The multi-carboxyl structure of the TMLA molecule can form a strong bond with the NiOx surface, enhancing the affinity of the SAM layer for the precursor. Simultaneously, the π-π interaction between TMLA and Me-4PACz can inhibit the aggregation of Me-4PACz molecules, thereby achieving a more uniform SAM distribution at the nanoscale. Previous studies have shown that co-adsorption of multi-carboxyl molecules can significantly improve the wettability of the precursor on hydrophobic SAM surfaces, effectively fill interfacial voids, and alleviate stress in perovskite films. 2. Secondly, the multiple carboxylic acid anchoring groups of TMLA not only enhance the contact with NiOx but also provide additional interfacial passivation, partially neutralizing NiOx surface defects. Under the action of co-assembled SAM, the nucleation and growth of perovskite crystals at the interface can be promoted, while suppressing non-radiative recombination and the formation of interfacial defects. Literature reports that modifying the NiOx interface with a Co-SAM strategy can promote perovskite crystal growth, accelerate carrier transport, and alleviate thin film stress, thereby significantly improving the optoelectronic performance and stability of the device. Therefore, this invention simultaneously improves interfacial passivation and carrier extraction efficiency through a TMLA / Me-4PACz hybrid SAM, thereby increasing the open-circuit voltage and conversion efficiency of the device. 3. Finally, thanks to the enhanced interfacial wettability and stability, the ultrathin perovskite layer prepared by this invention has higher density and lower defect density, ensuring the continuity and uniformity of the film and effectively improving the optoelectronic performance of the device.

[0018] The beneficial effects of this invention are: This invention improves the physical and chemical environment of the NiOx / SAM interface by co-assembling TMLA with Me-4PACz to form a hybrid SAM, reducing buried interface defects and thus improving the device efficiency and long-term stability of semi-transparent perovskite solar cells. Compared with other methods, the thin perovskite film prepared has lower pinhole rate and lower defect density, and the corresponding device has high photoelectric conversion efficiency and excellent visible light transmittance, which has important application value in the field of perovskite solar cell technology. Attached Figure Description

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 This is a SEM image of the semi-transparent perovskite film of Embodiment 1 of the present invention.

[0021] Figure 2 The images show the XRD patterns of the semi-transparent perovskite films of Embodiment 1 and Comparative Example 1 of the present invention.

[0022] Figure 3 This is a comparison chart of the stability of the semi-transparent perovskite devices in Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 A hybrid self-assembled monolayer construction method for improving NiOx interface stability in semi-transparent perovskite solar cells includes the following steps: S1. The ITO conductive glass substrate is ultrasonically cleaned for 5 minutes in sequence with glass cleaner, deionized water, acetone and ethanol. After cleaning, it is dried with nitrogen to obtain clean ITO glass. S2. Add 10mg of nickel oxide powder to 1mL of deionized water and ultrasonically disperse for 2-5min to obtain a uniform NiOx dispersion. Then spin-coat the NiOx dispersion onto a clean ITO glass at 4000rpm for 30s. After spin-coating, anneal in an oven at 100℃ for 15min to form a uniform NiOx film. S3. Add 0.106 mg of 1,2,4-benzenetricarboxylic acid and 0.5 mg of Me-4PACz (molar ratio 1:3) to 1 mL of isopropanol and stir magnetically at room temperature for 1 h to fully dissolve them and prepare a solution. Place the solution on a spin coater and spin coat it at 3000 rpm for 10 s to spread it. Then spin coat it at 5000 rpm for 30 s to form a uniform film. Finally, heat treat it at 110 °C for 10 min to obtain a substrate with a surface covered with mixed SAM. S4. According to the stoichiometric ratio, methylammonium chloride, lead iodide, lead bromide, cesium iodide, formamidinium hydroiodate, and methylammonium bromide are added to a mixed solvent of N,N-dimethylformamide and N-methylpyrrolidone (volume ratio 7:1) to prepare a 0.5 mol / L Cs solution. 0.05 (FA 0.95 MA 0.05 ) 0.95 Pb(I 0.95 Br 0.05 )3. Precursor fluids; S5. Spin-coat the precursor solution onto the substrate with mixed SAM on the surface using a two-step spin-coating method. First, spin-coat the precursor solution at 1000 rpm for 10 seconds to spread it evenly. Then, spin-coat at 4500 rpm for 40 seconds to accelerate solvent removal (add chlorobenzene anti-solvent dropwise at the last 10 seconds to promote crystal nucleation). Immediately after spin-coating, place the substrate in a furnace at 100°C for annealing for 30 minutes to form a well-crystallized perovskite film. S6. Prepare phenylethyl ammonium iodide solution (solvent isopropanol, concentration is 1 mg / mL), [6,6]-phenyl-C61-butyric acid isomethyl ester solution (solvent chlorobenzene, concentration is 15 mg / mL) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline solution (solvent chlorobenzene, concentration is 0.5 mg / mL), and spin-coat them sequentially on the surface of the perovskite film at rotation speeds of 4000 rpm, 3000 rpm and 5000 rpm for 30 s respectively to form an electron transport layer / passivation layer structure. Finally, use thermal evaporation to sequentially deposit a silver film and a molybdenum trioxide film to complete the self-assembled monolayer construction and obtain a translucent perovskite film. The SEM image of the semi-transparent perovskite film of Example 1 was obtained using an electron microscope, as shown below. Figure 1 As shown in the figure, the prepared perovskite film is dense and free of pinholes.

[0025] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, 1,2,4-benzenetricarboxylic acid is not added in step S3; only Me-4PACz is used to complete the construction and obtain the film.

[0026] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, in step S3, the molar ratio of 1,2,4-benzenetricarboxylic acid and Me-4PACz is controlled at 1:2 to complete the construction and obtain a thin film.

[0027] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, in step S3, the molar ratio of 1,2,4-benzenetricarboxylic acid and Me-4PACz is controlled at 1:4 to complete the construction and obtain a thin film.

[0028] The X-ray diffraction patterns of Example 1 and the comparative example were obtained using an X-ray diffractometer, as shown below. Figure 2 As shown in the figure, the diffraction peak intensity of Example 1 is higher than that of Comparative Example 1, which indicates that the perovskite film of Example 1 has better crystal quality. Examples 1 and 1 Comparative Example were assembled into a semi-transparent perovskite solar cell device. Stability test plots were obtained using maximum power point tracking, as shown below. Figure 3 As shown in the figure, it can be seen that compared with Comparative Example 1, the unencapsulated semi-transparent perovskite solar cell of Example 1 is more stable in the maximum power point stability test under the conditions of 25°C and 45% humidity.

[0029] The above-described Examples 1, 1, 2, and 3 were assembled into semi-transparent perovskite solar cells, and the efficiency and transmittance data (average transmittance from 400nm to 800nm) were measured and are shown in Table 1. Table 1 As can be seen from the test results in Table 1, the photoelectric conversion efficiency of Example 1 of the present invention is 14.90%, the average transmittance in the 300-800nm ​​band is 30%, and the open-circuit voltage is 1.15V. Compared with the comparative example, the present invention demonstrates excellent device efficiency and light transmission performance. Furthermore, the performance is best when the molar ratio of 1,2,4-phenyltricarboxylic acid and Me-4PACz is controlled at 1:3. Therefore, the present invention has important application value in the field of perovskite solar cell technology.

[0030] In the description of this specification, the 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 present invention. In this specification, the 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.

[0031] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for constructing a hybrid self-assembled monolayer to improve the NiOx interface stability of semi-transparent perovskite solar cells, characterized in that, Includes the following steps: S1. Clean the ITO conductive glass substrate and dry it to obtain clean ITO glass. S2. Add nickel oxide powder to deionized water, ultrasonically disperse for 2-5 minutes, then spin-coat it onto a clean ITO glass. After spin-coating, anneal to form a uniform NiOx film. S3. Add 1,2,4-benzenetricarboxylic acid and Me-4PACz to isopropanol and dissolve them under magnetic stirring at room temperature to prepare a solution. Spin-coat the solution onto the surface of a NiOx film. After spin-coating for 30-60 seconds, perform annealing to obtain a substrate with a surface covered by mixed SAM. S4. Add methylammonium chloride, lead iodide, lead bromide, cesium iodide, formamidinium hydroiodate, and methylammonium bromide to a solvent to prepare Cs. 0.05 (FA 0.95 MA 0.05 ) 0.95 Pb(I 0.95 Br 0.05 )3. Precursor fluids; S5. Spin-coat the precursor liquid onto the substrate covered with mixed SAM using a two-step spin-coating method. First, spin-coat at a slow speed for 8-10 seconds, then spin-coat at a fast speed for 30-50 seconds. In the last 5-10 seconds of spin-coating, add chlorobenzene for extraction. Finally, perform annealing to form a well-crystallized perovskite film. S6. Prepare solutions of phenylethyl ammonium iodide, isomethyl [6,6]-phenyl-C61-butyrate and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and spin-coat them sequentially onto the surface of the perovskite film for 30 seconds to form an electron transport layer / passivation layer structure. Finally, use thermal evaporation to sequentially deposit a silver film and a molybdenum trioxide film to complete the self-assembled monolayer construction and obtain a translucent perovskite film.

2. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In steps S2 and S3, the spin coating speed is 3000-5000 rpm.

3. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S2, the annealing temperature is 100-150℃ and the time is 15-30 min.

4. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S3, the concentration of 1,2,4-benzenetricarboxylic acid in the prepared solution is 0.1-0.2 mg / mL, and the concentration of Me-4PACz is 0.5-1 mg / mL.

5. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S3, the annealing temperature is 100-120℃ and the time is 10-20min.

6. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S4, the solvent is a mixture of N,N-dimethylformamide and N-methylpyrrolidone in a volume ratio of 7:

1.

7. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S4, the concentration of the precursor fluid is 0.5 mol / L.

8. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S5, the rotation speed for slow spin coating is 800-1000 rpm; the rotation speed for fast spin coating is 4000-5000 rpm.

9. The method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S5, the annealing temperature is 100-120℃ and the time is 20-40 min.

10. A method for constructing a hybrid self-assembled monolayer for improving the NiOx interface stability of a semi-transparent perovskite solar cell according to claim 1, characterized in that, In step S6, the concentration of the phenylethyl ammonium iodide solution is 1-5 mg / mL; the concentration of the [6,6]-phenyl-C61-butyric acid isomethyl ester solution is 15-20 mg / mL; and the concentration of the 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline solution is 0.5-1 mg / mL.

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