A method for preparing a perovskite cell by modifying an electron transport layer with a natural organic molecule

Abstract

The application discloses a method for preparing a perovskite cell by modifying an electronic transmission layer with a natural organic molecule, and relates to the technical field of photovoltaic devices. The technical scheme is as follows: tin dioxide solution is mixed with ectoine, and after ultrasonic treatment, a mixed solution of tin dioxide and ectoine is obtained by filtration; an ITO transparent conductive glass substrate which is cleaned and dried is subjected to ozone treatment, and then an Ec-SnO2 electronic transmission layer is deposited on the treated ITO substrate; a perovskite precursor solution is prepared, a perovskite thin film is prepared on the ITO substrate by using a spin coating method, and then is transferred to a heating table to perform annealing; a hole transmission layer is spin-coated on the perovskite thin film; finally, a silver electrode is deposited on the hole transmission layer by using a thermal evaporation technology. The method significantly improves the photoelectric conversion efficiency and stability of the perovskite solar cell, and the manufacturing process is simple and has low difficulty.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic device technology, and more specifically, to a method for preparing perovskite solar cells by modifying the electron transport layer with natural organic molecules. Background Technology

[0002] Perovskite solar cells have attracted widespread attention in recent years due to their high power conversion efficiency, low manufacturing cost, and solution processing characteristics. Their photoelectric conversion efficiency has rapidly increased from an initial 3.8% to over 26%, approaching the level of silicon-based cells. However, the main obstacle to their practical application is stability, particularly performance degradation caused by interface defects and residual stress. In typical nip structures, the electron transport layer (ETL) plays a crucial role in charge extraction and transport; tin dioxide (SnO2) is particularly valuable due to its high electron mobility (240 cm⁻¹). 2 With its wide bandgap (3.6 eV), high light transmittance (>85%), and low photocatalytic activity, it is widely used as an ETL material.

[0003] However, SnO2 still has the following problems in practical applications:

[0004] Poor dispersibility: SnO2 nanoparticles tend to agglomerate in the dispersion, resulting in poor film coverage and high porosity, which affects the crystallization quality and interfacial contact of the perovskite layer.

[0005] Surface defects: oxygen vacancies and uncoordinated Sn 4+ Ions exacerbate interfacial recombination, significantly reducing charge extraction efficiency and affecting photoelectric conversion performance;

[0006] Interface stress and poor contact: The difference in thermal expansion coefficients between SnO2 and perovskite leads to residual stress at the interface, which further weakens the interface stability and device performance.

[0007] Unoptimized SnO2 films result in nonradiative recombination rates as high as 10. 4 s -1 This directly limits battery efficiency and stability;

[0008] Low adjustability of processing materials: The properties of industrial SnO2 materials are fixed, making it difficult to achieve personalized interface optimization, which restricts further performance improvement.

[0009] Therefore, the present invention aims to provide a method for preparing perovskite solar cells by modifying the electron transport layer with natural organic molecules, in order to solve the above-mentioned problems. Summary of the Invention

[0010] The purpose of this invention is to provide a method for preparing perovskite solar cells by modifying the electron transport layer with natural organic molecules. This invention can effectively improve the performance of the SnO2 electron transport layer, passivate its surface defects through the interaction between edokines and SnO2, reduce electron-hole recombination, and improve the photoelectric conversion efficiency and stability of perovskite solar cells. At the same time, this invention does not require changes to the existing cell preparation process, is simple and easy to implement, and can significantly improve the stability of the device, especially the stability under long-term humid heat and ultraviolet light irradiation conditions.

[0011] The above-mentioned technical objective of this invention is achieved through the following technical solution: a method for preparing perovskite solar cells by modifying the electron transport layer with natural organic molecules, comprising the following steps:

[0012] S1. Prepare a 10wt% SnO2 colloidal dispersion, add a certain concentration of ectoine, perform ultrasonic treatment, and let stand to ensure thorough mixing to obtain a mixed solution of tin dioxide and ectoine.

[0013] S2. Place the cleaned ITO glass substrate in a spin coating device, add the mixed solution and spin coat at a certain speed, and then perform annealing treatment to form a SnO2 electron transport layer on the ITO glass substrate.

[0014] S3. N,N-dimethylformamide and dimethyl sulfoxide were mixed as a mixed solvent to prepare a 1.3M PbI2 solution. 0.2M methylammonium chloride and formamidinium iodide were mixed in a certain proportion to prepare a mixed organic halide solution.

[0015] S4. Spin-coat a PbI2 solution onto the SnO2 electron transport layer, anneal to form a PbI2 film, and continue to spin-coat a mixed organic halide solution onto the PbI2 film, anneal to form a perovskite film.

[0016] S5. Spin-coat the hole transport layer material Spiro-OMeTAD onto the perovskite thin film to form a hole transport layer;

[0017] S6. A silver electrode is deposited on the hole transport layer using thermal evaporation technology.

[0018] The present invention is further configured such that: in step S1, the concentration of ectoine added is 0.25 mg / mL, the ultrasonic treatment time is 30 minutes, and the standing time is 30 minutes.

[0019] The present invention is further configured such that: the spin coating conditions in step S2 are 3000 rpm / 30 seconds, the annealing temperature is 150°C, and the time is 20 minutes.

[0020] The present invention is further configured such that the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide in step S3 is 4:1.

[0021] The present invention is further configured such that: in step S4, the spin-coating conditions for the PbI2 solution are 1500 rpm / 30 seconds, the heating conditions for the PbI2 film are 70°C / 10 minutes, the spin-coating conditions for the mixed organic halide solution are 2000 rpm / 30 seconds, and the annealing conditions for the perovskite film are 100°C / 10 minutes.

[0022] The present invention is further configured such that the spin coating condition for the hole transport layer in step S5 is 3000 rpm / 30 seconds.

[0023] The present invention is further configured such that: in step S6, the thickness of the silver electrode is 100 nm, and the evaporation rate is...

[0024] In summary, the present invention has the following beneficial effects:

[0025] 1. This invention effectively passivates defects on the SnO2 surface through the interaction between edokine molecules and SnO2, reduces non-radiative recombination, and improves electron extraction efficiency.

[0026] 2. The preparation method provided by the present invention is simple and easy to implement, and can significantly improve the photoelectric conversion efficiency and stability of perovskite solar cells, especially the stability under humid heat and ultraviolet light irradiation conditions.

[0027] 3. The preparation method in this invention does not require changes to the existing battery manufacturing process and is suitable for large-scale production. Attached Figure Description

[0028] Figure 1 This is a top-view AFM diagram of the top of SnO2 and Ec-SnO2 in an embodiment of the present invention ((a) is a top-view AFM diagram of the top of SnO2, and (b) is a top-view AFM diagram of the top of Ec-SnO2).

[0029] Figure 2 This is a schematic diagram of the effect of edokine on the crystallinity of PVK and the ultraviolet-visible spectrum in the embodiments of the present invention ((a) is a diagram of the effect of pre-embedded edokine on the crystallinity of PVK by X-ray diffraction analysis, and (b) is a diagram of ultraviolet-visible spectrum).

[0030] Figure 3 These are top-view SEM images of PVK deposition in the embodiments of the present invention ((a) is a top-view SEM image of the top of PVK deposition on SnO2, and (b) is a top-view SEM image of the top of PVK deposition on Ec-SnO2).

[0031] Figure 4 This is a comparison chart of the forward and reverse voltage scan efficiency of the control group and the experimental group in this embodiment of the invention;

[0032] Figure 5 This is a schematic diagram of the long-term stability test results of perovskite solar cells in an embodiment of the present invention. ((a) shows the long-term stability results of unencapsulated PSCs stored in air with a relative humidity of 15-20%, and (b) shows the results of continuous ultraviolet irradiation (365nm, 50mW / cm²). 2 (See the long-term operational stability results diagram). Detailed Implementation

[0033] The following is in conjunction with the appendix Figure 1-5 The present invention will be described in further detail below.

[0034] Example: A method for preparing perovskite solar cells by modifying the electron transport layer with natural organic molecules, comprising the following steps:

[0035] S1: Take 10 mL of SnO2 colloidal dispersion with a concentration of 10 wt%.

[0036] S2: Add ectoine molecules to the SnO2 dispersion at a ratio of 0.25 mg / mL and sonicate at room temperature for 30 minutes to ensure that ectoine is fully dispersed and bound to SnO2.

[0037] S3: Let the above mixture stand for 30 minutes to ensure the homogeneity and stability of the solution.

[0038] S4: Place the cleaned ITO glass substrate in a spin coater, drop 0.1 mL of SnO2 / edokine mixed solution onto the substrate surface, and spin coat at 3000 rpm for 30 seconds to ensure the film is uniform and form a SnO2 electron transport layer.

[0039] S5: Place the deposited ITO glass slide on a hot stage at 150°C and heat for 20 minutes to form a dense and crack-free SnO2 electron transport layer.

[0040] S6: Perovskite films were prepared using a two-step spin-coating method. First, a 1.2M PbI2 solution (DMF and DMSO in a volume ratio of 4:1) was prepared and spin-coated at 1500 rpm for 30 seconds, followed by heating at 70°C for 10 minutes to form a PbI2 film. Then, a 0.2M solution of methylammonium iodide (MAI) and methylammonium bromide (MABr) (molar ratio of 4:1) was prepared and spin-coated onto the PbI2 film at 2000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes to form a perovskite film.

[0041] S7: Spiro-OMeTAD hole transport layer material was spin-coated onto a perovskite film. The solution was 70 mg / mL Spiro-OMeTAD dissolved in chlorobenzene, with a drop volume of 0.1 mL. The spin-coating speed was 3000 rpm, and the spin-coating time was 30 seconds.

[0042] S8: A silver (Ag) electrode is deposited on top of the hole transport layer using thermal evaporation technology. The electrode thickness is 100 nm, and the evaporation rate is [missing information].

[0043] In this preferred embodiment, the method also includes testing the photoelectric performance of the perovskite solar cell, specifically including photoelectric conversion efficiency (PCE), open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF), such as... Figure 4 As shown in the figure, it is clear that the forward and reverse scanning efficiency of the experimental group is much higher than that of the control group. This indicates that passivating the surface defects of SnO2 with edokine has a significant effect, thus achieving an efficiency improvement of more than 3%. In addition, long-term stability tests were also conducted in this embodiment under 365nm ultraviolet light (50mW / cm²). 2 After 90 hours of irradiation, the efficiency decay was observed. Figure 5 (a) The control group retained approximately 67.79% of its original efficiency, while the experimental group retained 85.19% of its initial efficiency; after storage for 1700 hours at a relative humidity of 15%-20% ( Figure 5 (b) The control group retained 81.52% of the initial efficiency, while the experimental group's efficiency remained almost unchanged, maintaining 93.21% of the initial efficiency.

[0044] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing a perovskite cell by modifying an electron transport layer with a natural organic molecule, characterized in that: The method comprises the following steps: S1, preparing a SnO2 colloidal dispersion solution with a concentration of 10wt%, adding a certain concentration of ectoine, performing ultrasonic treatment, and standing to ensure sufficient mixing, to obtain a mixed solution of SnO2 and ectoine; S2, placing a cleaned ITO glass substrate in a spin coating device, dropping the mixed solution and spin coating at a certain speed, and then performing annealing treatment to form a SnO2 electron transport layer on the ITO glass substrate; S3, mixing N,N-dimethylformamide and dimethyl sulfoxide as a mixed solvent to prepare a PbI2 solution with a concentration of 1.3M, and mixing 0.2M methylammonium chloride and formamidinium iodide in a certain proportion to prepare a mixed organic halide solution; S4, spin coating the PbI2 solution on the SnO2 electron transport layer, annealing to form a PbI2 film, and then spin coating the mixed organic halide solution on the PbI2 film, and annealing to form a perovskite film; S5, spin coating a hole transport layer material Spiro-OMeTAD on the perovskite film to form a hole transport layer; S6, depositing a silver electrode on the hole transport layer by using a thermal evaporation technology.

2. The method of claim 1, wherein the method is characterized in that: In the step S1, the added concentration of ectoine is 0.25mg / mL, the ultrasonic treatment time is 30 minutes, and the standing time is 30 minutes.

3. The method of claim 1, wherein the method is characterized in that: In the step S2, the spin coating condition is 3000rpm / 30 seconds, the annealing temperature is 150℃, and the time is 20 minutes.

4. The method of claim 1, wherein the method is characterized in that: In the step S3, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is 4:

1.

5. The method of claim 1, wherein the method is characterized by: In the step S4, the spin coating condition of the PbI2 solution is 1500rpm / 30 seconds, the heating condition of the PbI2 film is 70℃ / 10 minutes, the spin coating condition of the mixed organic halide solution is 2000rpm / 30 seconds, and the annealing condition of the perovskite film is 100℃ / 10 minutes.

6. The method of claim 1, wherein the method is characterized by: In the step S5, the spin coating condition of the hole transport layer is 3000rpm / 30 seconds.

7. The method of claim 1, wherein the method is characterized by: The thickness of the silver electrode in step S6 is 100 nm, and the evaporation rate is 0.1 nm / s

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