Universal surface passivator based on two-dimensional nanosheet perovskite solar cell

Abstract

The invention discloses a universal surface passivator based on a two-dimensional nanosheet perovskite solar cell, and relates to the technical field of perovskite solar cells, and the universal surface passivator is technically characterized in that the universal surface passivator is a two-dimensional PbI2 nanosheet, the two-dimensional PbI2 nanosheet is prepared by a stripping method, and the two-dimensional PbI2 nanosheet is a PbI2 nanosheet. The method is suitable for perovskite solar cells with upright structures and inverted structures. The preparation of the solar cell is completed by forming the first charge transport layer on the surface of the substrate, coating the perovskite precursor solution and heating and curing the perovskite precursor solution to form the perovskite thin film, then coating the passivation solution and heating and curing the passivation solution to form the passivation layer, and finally forming the hole transport layer and evaporating the electrode. The two-dimensional PbI2 nanosheet passivation layer can effectively reduce the interface defect state density, and significantly improve the charge transfer efficiency and the long-term stability of the device. Experimental results show that the perovskite solar cell has higher photoelectric conversion efficiency and longer service life, and has important commercial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cells, and in particular to a universal surface passivator based on two-dimensional nanosheet perovskite solar cells. Background Art

[0002] Perovskite solar cells have attracted extensive attention due to their excellent photoelectric conversion efficiency and low-cost preparation process. In the study of surface passivation of perovskite solar cells, although traditional passivation materials such as organic molecules and inorganic oxides can improve device performance to a certain extent, their interface passivation effect is not ideal and cannot significantly improve the charge transfer efficiency and long-term stability of the device. Therefore, the development of new surface passivation materials is crucial to improving the performance of perovskite solar cells.

[0003] At present, a variety of surface passivation materials have been proposed in the field of perovskite solar cell technology, including organic molecules and inorganic oxides. These materials can improve the photoelectric performance of perovskite solar cells to a certain extent, but due to their limited interface passivation effect, the charge transfer efficiency and device stability have not been significantly improved. In addition, the chemical stability and charge transfer characteristics of these materials are also insufficient, which limits the commercialization process of perovskite solar cells.

[0004] Although existing passivation materials play a certain role in perovskite solar cells, their performance in terms of interface passivation effect, charge transfer efficiency and device stability is not satisfactory. The main problems include high interface defect state density, which leads to increased non-radiative recombination and affects the photoelectric conversion efficiency; and insufficient chemical stability and charge transfer characteristics, which affect the long-term stability and life of the device. Therefore, there is an urgent need to develop new surface passivation materials to achieve more effective interface passivation, improve charge transfer efficiency, and enhance the stability and life of the device. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problems and provide a universal surface passivator based on two-dimensional nanosheet perovskite solar cells. It not only solves the problem of unsatisfactory interface passivation effect in the prior art, but also significantly improves the performance of perovskite solar cells, providing a new technical approach for the further development and commercialization of perovskite solar cells.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is as follows: a universal surface passivator based on two-dimensional nanosheet perovskite solar cells, wherein the universal surface passivator is a two-dimensional PbI2 nanosheet, and the two-dimensional PbI2 nanosheet is prepared by a stripping method and is suitable for perovskite solar cells with upright structure and inverted structure.

[0007] Furthermore, the thickness of the surface passivator does not exceed 100 nm.

[0008] Furthermore, the preparation method of the two-dimensional PbI2 nanosheets includes mixing the two-dimensional PbI2 material with isopropanol, ultrasonically treating the mixture, centrifuging and taking the supernatant to obtain a passivation solution.

[0009] Furthermore, the concentration of the two-dimensional PbI2 nanosheets in the passivation solution is 1-10 mg / ml.

[0010] Furthermore, the two-dimensional PbI2 nanosheets are obtained by ultrasonic treatment for 1-10 hours and then centrifugation.

[0011] Furthermore, the two-dimensional PbI2 nanosheets are used as a passivation layer in perovskite solar cells, effectively reducing the interface defect state density and promoting charge transfer.

[0012] Another object of the present invention is to provide a perovskite solar cell using the above-mentioned two-dimensional PbI2 nanosheet as a universal surface passivator, which is characterized in that it includes an electron transport layer, a perovskite layer, a passivation layer and a hole transport layer, wherein the passivation layer is the two-dimensional PbI2 nanosheet.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned perovskite solar cell, comprising the following steps:

[0014] A) forming a first charge transport layer on the surface of the substrate;

[0015] B) coating a perovskite precursor solution on the surface of the first charge transport layer, heating and curing, and forming a perovskite film;

[0016] C) coating a passivation solution on the surface of the perovskite film, performing micro-etching, and then heating and curing to form a passivation layer; the passivation solution comprises isopropanol and two-dimensional PbI2 nanosheets, and the concentration of the two-dimensional PbI2 nanosheets is preferably 1-10 mg / ml;

[0017] D) forming a hole transport layer on the surface of the passivation layer, and evaporating an electrode on the surface of the hole transport layer to obtain a surface passivated perovskite solar cell.

[0018] Furthermore, the perovskite precursor solution includes an organic salt and an inorganic salt; the organic salt is one or more of FAI, MAI, MACl, FABr and MABr; the inorganic salt is one or more of PbI2, PbBr2, PbCl2, CsBr, CsI and SnI2.

[0019] Compared with the prior art, the beneficial effects of this solution are as follows: The present invention uses two-dimensional PbI2 nanosheets as the surface passivation material of perovskite solar cells, which has significant beneficial effects. First, the two-dimensional structure of the two-dimensional PbI2 nanosheets can be tightly combined with the surface of the perovskite layer, providing a larger interface contact area and effectively reducing the interface defect state density. This structural advantage makes the two-dimensional PbI2 nanosheets far superior to traditional organic molecules and inorganic oxides in terms of interface passivation effect, and can significantly improve the charge transfer efficiency and long-term stability of the device. Secondly, the two-dimensional PbI2 nanosheets exhibit higher chemical stability and better charge transfer characteristics, which are crucial to the commercialization of perovskite solar cells because they can improve the photoelectric conversion efficiency and stability of the battery and extend the service life of the battery.

[0020] In addition, the introduction of two-dimensional PbI2 nanosheets in the present invention not only improves the photoelectric performance of perovskite solar cells, but also further improves the photoelectric conversion efficiency of the cells by reducing interface defects and inhibiting non-radiative recombination. Experimental results show that perovskite solar cells using two-dimensional PbI2 nanosheet passivation layers are superior to the prior art in key performance indicators such as open circuit voltage, short circuit current, fill factor and efficiency. Therefore, the performance improvement and long-term stability of the perovskite solar cells of the present invention provide a new technical approach with important commercial application prospects and market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a box diagram of the open circuit voltage of the perovskite battery in the embodiment of the present invention and the comparative example;

[0022] Figure 2 It is a box plot of the filling factor of the perovskite battery in the embodiment of the present invention and the comparative example;

[0023] Figure 3 1 is a box plot of the efficiency of the perovskite battery in the embodiment of the present invention and the comparative example;

[0024] Figure 4 It is a schematic diagram of the structure of the surface passivated perovskite solar cell in the present invention;

[0025] Among them, 1 is a hole transport layer, 2 is a passivation layer, 3 is a perovskite layer, 4 is an electron transport layer, and 5 is a substrate. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0028] Embodiment 1: A method for preparing a perovskite solar cell, comprising the following steps:

[0029] Backing: 1.5*1.5cm 2 ITO film (glass thickness 1mm, ITO film thickness 150nm); SnO2 film (thickness 20nm) set on the surface of the substrate; 1.5*1.5cm 2 Indium tin oxide (ITO) glass (glass thickness 2 mm, ITO film thickness 150 nm) was cleaned with ethanol, isopropyl alcohol (IPA) and acetone for 30 minutes each, and then dried with a nitrogen gun.

[0030] The tin dioxide (SnO2) stock solution was diluted with ultrapure water in a volume ratio of 1:3, and the SnO2 precursor solution was obtained by thorough stirring; 40 μL of the SnO2 precursor solution was evenly spread on the surface of the ITO conductive glass, and the parameters of the coating machine were set to a speed of 4000 rpm / s and a time of 30 seconds; then it was placed on a 150°C hot stage for annealing for 30 minutes to obtain a SnO2 film (20 nm). The SnO2 film prepared above was placed in a UV ozone cleaner for 30 minutes for subsequent spin coating.

[0031] Weigh 600 mg of lead iodide (PbI2) and 17 mg of cesium iodide (CsI) and dissolve them in 900 μL of N,N-dimethylformamide (DMF) and 100 μL of dimethyl sulfoxide (DMSO) solution, heat and stir at 70°C to fully dissolve them, and obtain PbI2 precursor solution A. Dissolve 110 mg of formamidine hydroiodide (FAI) and 23.15 mg of methylamine chloride (MACl) in 1 mL of IPA solution, stir to fully dissolve them, and obtain organic salt solution B.

[0032] Take 20 μL of solution A and spread it evenly on the surface of the above SnO2 film. The parameters of the coating machine are set to a speed of 2000 rpm / s and a time of 50 s. At the 30th second, take 40 μL of solution B and spread it evenly on the surface of the coating formed after the prepared solution A. Then place it on a 150°C hot plate for annealing for 15 minutes to obtain a perovskite film (400 nm).

[0033] Weigh 10 mg of lead iodide and add it to 10 ml of isopropanol. Ultrasonicate it in an ultrasonic machine for 6 hours, then centrifuge it in a centrifuge at 3000 rpm / min for 30 minutes, take 8 ml of the supernatant, and obtain a translucent yellow solution C. Take 40 μl of solution C and spread it evenly on the surface of the above perovskite film. The parameters of the coating machine are set to 3000 rpm / s for 30 seconds; then place it on a hot plate at 100°C for annealing for 1 minute to form a passivation layer;

[0034] Weigh 520 mg of bis(trifluoromethanesulfonyl)imide lithium salt (Li-TFSI) and dissolve it in 1 mL of acetonitrile (CAN), and stir it thoroughly to obtain a Li-TFSI solution. Then weigh 36.15 mg of 2,2,7,7-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (Spiro-OMeTAD) and dissolve it in 1 mL of chlorobenzene, and stir it thoroughly until dissolved; then add 8.75 μL of 4-tert-butylpyridine (TBP) solution and 20 μL of Li-TFSI solution, and stir it thoroughly to obtain a hole transport layer solution.

[0035] Take 40 μL of the hole transport layer solution and spread it evenly on the surface of the passivation layer. Set the parameters of the coating machine to 4000 rpm / min and 30 s to obtain a hole transport layer (50 nm). Transfer the hole transport layer to the thermal evaporation equipment and the vacuum degree reaches 1×10 -5 Pa, the electrode (Ag) was evaporated to a thickness of 100 nm; it was then placed in an oxygen glove box for one night for oxidation to obtain a battery.

[0036] Example 2: A perovskite solar cell was prepared according to the method of Example 1, except that solution C was annealed on a hot plate at 100° C. for 5 min to form a passivation layer.

[0037] Example 3: A perovskite solar cell was prepared according to the method of Example 1, except that solution C was annealed on a hot plate at 150° C. for 1 min to form a passivation layer.

[0038] Example 4: A perovskite solar cell was prepared according to the method of Example 1, except that solution C was annealed on a hot plate at 150° C. for 5 min to form a passivation layer.

[0039] Example 5: A preparation device for a perovskite solar cell

[0040] Substrate: 1.5*1.5cm 2 ITO film (glass thickness 1mm, ITO film thickness 150nm);

[0041] 1.5*1.5cm 2 Indium tin oxide (ITO) glass (glass thickness 2mm, ITO film thickness 150nm) was cleaned with detergent, pure water, anhydrous ethanol and acetone for 30 minutes each, and dried with nitrogen gas. NiOx was ultrasonically dispersed in ultrapure water at 10mg / ml, and 60μL of NiOx dispersion was spread on the surface of ITO conductive glass. The parameters of the coating machine were set to 2000rpm / s and 30s; then it was placed on a 120℃ hot plate for annealing for 15min to obtain a NiOx film (20nm).

[0042] Weigh 691.5 mg of lead iodide (PbI2) and dissolve it in 900 μL of N,N-dimethylformamide (DMF) and 100 μL of dimethyl sulfoxide (DMSO) solution, heat and stir at 70°C to fully dissolve it, and obtain PbI2 precursor solution D. Dissolve 90 mg of formamidine hydroiodide (FAI), 6.4 mg of potassium ammonium iodide (MAI), and 18 mg of methylamine chloride (MACl) in 1 mL of IPA solution, stir to fully dissolve it, and obtain organic salt solution E.

[0043] Take 40 μL of solution D and spread it evenly on the surface of the above NiOx film. The parameters of the spreader are set to a speed of 2000 rpm / s and a time of 20 s. Take 40 μL of solution E and spread it evenly on the surface of the coating formed after the prepared solution D. The parameters of the spreader are set to a speed of 2500 rpm / s and a time of 30 s. Then place it on a 100°C hot plate for annealing for 20 minutes to obtain a perovskite film (600 nm).

[0044] Weigh 10 mg of lead iodide and add it to 10 ml of isopropanol. Ultrasonicate it in an ultrasonic machine for 6 hours, then centrifuge it in a centrifuge at 3000 rpm / min for 30 minutes, take 8 ml of the supernatant, and obtain a translucent yellow solution C. Take 40 μl of solution C and spread it evenly on the surface of the above perovskite film. The parameters of the coating machine are set to 3000 rpm / s for 30 seconds; then place it on a hot plate at 100°C for annealing for 1 minute to form a passivation layer;

[0045] The film forming the passivation layer is transferred to the thermal evaporation equipment, and the vacuum degree reaches 1×10 -5 Pa, the hole transport layer (C 60 ), bathocuproin (BCP) and electrode (Ag) with thicknesses of 30nm, 6nm and 100nm respectively; and a battery was obtained.

[0046] Comparative Example 1: A perovskite solar cell was prepared according to the method of Example 1, except that solution C, a two-dimensional PbI2 solution, was not used, but isopropanol was used.

[0047] Comparative Example 2: A perovskite solar cell was prepared according to the method of Example 5, except that solution C (two-dimensional PbI2 dispersion) was not used but isopropanol was used.

[0048] Performance test: PCE was used to test the current density-voltage (JV) curves of the batteries prepared in the embodiment and the comparative example. The test was completed on the Keysight 2400 system. Test conditions: the simulated light intensity was 100 mW cm -2 (AM 1.5G) scanning rate is 0.1Vs -1 (step size is 0.02V, time delay is 200ms), the scanning interval is 1.2V to -0.2V, and the power output of the xenon lamp is calibrated by the KG5 standard Si battery of the NERL (National Renewable Energy Laboratory). The test results are as follows Figures 1 to 4 And as shown in Table 1.

[0049] Table 1 Battery performance test results prepared in Examples and Comparative Examples

[0050] Open circuit voltage(V) <![CDATA[Short-circuit current (mAcm -2 )]]> Fill factor (%) efficiency(%) Comparative Example 1 1.12 23.24 73.08 19.1 Example 1 1.12 23.52 70.36 18.59 Example 2 1.13 23.5 72.70 19.34 Example 3 1.13 23.55 75.00 20.02 Example 4 1.15 23.69 75.53 20.58 Comparative Example 2 1.12 25.15 77.37 21.85 Example 5 1.13 25.13 80.66 22.85

[0051] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. Universal surface passivator based on two-dimensional nanosheet perovskite solar cells, characterized by: The universal surface passivator is a two-dimensional PbI2 nanosheet, which is prepared by a stripping method and is suitable for perovskite solar cells with an upright structure and an inverted structure.

2. The universal surface passivator according to claim 1, characterized in that: The thickness of the surface passivating agent does not exceed 100 nm.

3. The universal surface passivator according to claim 1, characterized in that: The preparation method of the two-dimensional PbI2 nanosheet comprises mixing the two-dimensional PbI2 material with isopropanol, performing ultrasonic treatment, centrifuging and taking the supernatant to obtain a passivation solution.

4. The universal surface passivator according to claim 1, characterized in that: The concentration of the two-dimensional PbI2 nanosheets in the passivation solution is 1-10 mg / ml.

5. The universal surface passivator according to claim 1, characterized in that: The two-dimensional PbI2 nanosheets are obtained by ultrasonic treatment for 1-10 hours and then centrifugation.

6. The universal surface passivator according to claim 1, characterized in that: The two-dimensional PbI2 nanosheet is used as a passivation layer in a perovskite solar cell, effectively reducing the interface defect state density and promoting charge transfer.

7. A perovskite solar cell using the two-dimensional PbI2 nanosheet as claimed in any one of claims 1 to 6 as a universal surface passivator, characterized in that: It includes an electron transport layer, a perovskite layer, a passivation layer and a hole transport layer, wherein the passivation layer is the two-dimensional PbI2 nanosheet.

8. A method for preparing a perovskite solar cell as claimed in claim 7, characterized in that: The following steps are involved: A) forming a first charge transport layer on the surface of the substrate; B) coating a perovskite precursor solution on the surface of the first charge transport layer, heating and curing, and forming a perovskite film; C) coating the passivation solution on the surface of the perovskite film, performing micro-etching, and then heating and curing to form a passivation layer; The passivation solution comprises isopropanol and two-dimensional PbI2 nanosheets, and the concentration of the two-dimensional PbI2 nanosheets is preferably 1-10 mg / ml; D) forming a hole transport layer on the surface of the passivation layer, and evaporating an electrode on the surface of the hole transport layer to obtain a surface passivated perovskite solar cell.

9. The method according to claim 8, characterized in that: The perovskite precursor solution includes an organic salt and an inorganic salt; the organic salt is one or more of FAI, MAI, MACl, FABr and MABr; the inorganic salt is one or more of PbI2, PbBr2, PbCl2, CsBr, CsI and SnI2.

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