Perovskite solar cell preparation method based on redox dynamic passivation

Abstract

The invention relates to the technical field of solar cells, in particular to a preparation method of a perovskite solar cell based on redox dynamic passivation, which comprises the step of adding 2-4mg / mL of anthraquinone compound in the process of preparing a lead iodide film or a perovskite light absorption layer. The anthraquinone compound is introduced as a redox reaction mediator in the process of preparing the perovskite solar cell to dynamically oxidize and reduce generated ions and simple substances, so that harmful defects are passivated, and the stability and efficiency of a device are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a preparation method of a perovskite solar cell based on redox dynamic passivation. Background Art

[0002] Due to its excellent carrier mobility, high defect tolerance, adjustable bandgap, and low cost, perovskite solar cells have received extensive attention from researchers worldwide in recent years and are considered the most promising new generation of photovoltaic technologies.

[0003] However, the main factor currently limiting its commercial application and development is the stability problem, especially the stability problem related to defects. The intrinsic properties of perovskite materials make it inevitable to generate multiple types and high concentrations of defects during the preparation process. These defects will combine with photo-generated carriers, causing serious non-radiative recombination, thereby reducing the open-circuit voltage, fill factor, and efficiency of the device. More importantly, defects can also serve as active sites for water and oxygen invasion, inducing device / film degradation and seriously affecting the stability of the device. In addition, new defects will also be generated during the operation of the device. For example, under light illumination conditions, ion migration will occur, and the migrating ions will leave a large number of vacancies and interstitial ions, thus forming more charge defects in the perovskite film, ultimately leading to phenomena such as phase separation, current density-voltage hysteresis, and phase segregation. Moreover, a low-bandgap iodine-rich phase will be formed as a charge recombination center, resulting in a decrease in open-circuit voltage and device photo-instability. Especially for perovskite films with PbI2 at grain boundaries, there will be a large amount of lead iodide at the grain boundaries of two-step perovskite films. The Pb 2+ ions are easily reduced to metallic lead, which is not conducive to the stability and efficiency of the device. Summary of the Invention

[0004] In order to solve the defects existing in the prior art, the present invention provides a preparation method of a perovskite solar cell based on redox dynamic passivation. By introducing anthraquinone compounds as redox reaction mediators during the preparation of perovskite solar cells, the generated ions and elemental substances are dynamically oxidized and reduced to passivate harmful defects, ultimately improving the stability and efficiency of the device.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a preparation method of a perovskite solar cell based on redox dynamic passivation, including: adding 2-4 mg / mL of anthraquinone compounds during the preparation of lead iodide film or the preparation of perovskite light-absorbing layer.

[0007] Preferably, the anthraquinone compound is selected from any one or more of 2-chloroanthraquinone, 2-bromoanthraquinone, 2-aminoanthraquinone, 2-anthraquinone sulfonic acid, anthraquinone-2-carbonyl chloride, 1-amino-4-bromoanthraquinone-2-sulfonic acid, 1-anthraquinone oxide, 1-nitroanthraquinone ester, 2-nitroanthraquinone-8-sulfonic acid, 1-nitroanthraquinone-5-sodium sulfonate, 1,5-dinitroanthraquinone, 1,5-diaminoanthraquinone, 1,2-dihydroxy-3-nitroanthraquinone, 1-nitro-2-methylanthraquinone, and 1,4-dihydroxyanthraquinone-2-sulfonic acid.

[0008] Preferably, the process for preparing the lead iodide film includes: adding the anthraquinone compound to a lead iodide precursor solution, and then spin-coating on a substrate and annealing.

[0009] Preferably, the process for preparing the perovskite light-absorbing layer includes: adding an anthraquinone compound to a perovskite precursor solution, and then spin-coating on a substrate and annealing.

[0010] Preferably, the solute in the perovskite precursor solution includes an organic halide of the chemical formula AX type, where A includes one or more of formamidine or methylamine; where X is a halogen element, and the halogen element includes one or more of F, I, Br, and Cl elements.

[0011] Preferably, the preparation method further includes cleaning the conductive glass, preparing the electron transport layer, preparing the hole transport layer, and preparing the back electrode.

[0012] Preferably, the material of the electron transport layer is selected from any one or more of C 60 、PCBM, TiO2, SnO2, Nb2O5.

[0013] Preferably, the process for preparing the hole transport layer includes: mixing Spiro-OMeTAD, a dopant, a lithium salt, and a cobalt salt and then spin-coating.

[0014] In a second aspect, the present invention provides a perovskite solar cell prepared by the above preparation method.

[0015] Preferably, the structure of the perovskite solar cell includes a conductive glass, an electron transport layer, a lead iodide film, a perovskite light-absorbing layer, a hole transport layer, and a back electrode.

[0016] The beneficial effects of the present invention are:

[0017] When preparing the perovskite solar cell of the present invention, anthraquinone compounds are added during the preparation of the lead iodide film or the preparation of the perovskite light-absorbing layer. On the one hand, the anthraquinone compounds can dynamically oxidize and reduce the ions and simple substances generated by the perovskite, and can passivate some harmful defects newly generated during the operation of the device, so as to improve the stability and efficiency of the device; on the other hand, the functional groups on the anthraquinone compound molecules, such as amino groups, carboxyl groups, sulfonate groups, etc., have the role similar to Lewis acids or bases, and can coordinate with the uncoordinated lead ions or lead iodide in the perovskite, and the halogen atoms in the functional groups can fill into the anion vacancies in the perovskite. The present invention can passivate the defects in the perovskite precursor solution by regulating these functional groups, reduce the hysteresis effect, and reduce the halide segregation existing therein, effectively regulate the growth process of the perovskite film, and contribute to obtaining a high-quality light-absorbing material with few defects, further improving the stability and efficiency of the device.

[0018] The perovskite solar cell prepared by the method of the present invention has excellent electrochemical performance, the cell efficiency is above 24%, and the storage stability is above 90%. Brief Description of the Drawings

[0019] Figure 1 It is the J-V characteristic curve diagram of the solar cells obtained in Example 1 and Comparative Example 1.

[0020] Figure 2 It is the EQE characteristic curve diagram of the solar cells obtained in Example 1 and Comparative Example 1.

[0021] Figure 3 It is the AFM characterization diagram of the perovskite light-absorbing layer prepared in Example 1 and Comparative Example 1.

[0022] Figure 4 It is the SEM characterization diagram of the perovskite light-absorbing layer prepared in Example 1 and Comparative Example 1.

[0023] Figure 5 It is the photoluminescence characterization diagram of the perovskite light-absorbing layer prepared in Example 1 and Comparative Example 1. Detailed Description of the Invention

[0024] In order to enable those skilled in the art to better understand the technical solution of the invention, the present invention will be further described in detail below in conjunction with the specific embodiments.

[0025] In order to passivate the harmful defects of the perovskite and improve the stability and efficiency of the solar cell. The present invention first provides a preparation method of a perovskite solar cell based on redox dynamic passivation, including: adding 2-4 mg / mL of anthraquinone (AQ) compounds during the preparation of the lead iodide film or the preparation of the perovskite light-absorbing layer.

[0026] The concentration of the anthraquinone compound in the present invention is the concentration of the mass of the anthraquinone compound in the volume of the precursor solvent when preparing the lead iodide film or the perovskite light-absorbing layer. For example, when preparing the lead iodide film, the volume of the solvent in the lead iodide precursor solution is 1 mL, and 2 mg of the anthraquinone compound is added, then the concentration of the anthraquinone compound is 2 mg / mL.

[0027] The addition of the anthraquinone compound in the present invention mainly has two aspects of functions: on the one hand, through its reversible redox characteristics, it can dynamically passivate the newly generated ionic defects and elemental substances during the operation of the device; on the other hand, functional groups such as amino, carboxyl, and sulfonate groups on its molecule can act as Lewis acids / bases to coordinate with the uncoordinated lead ions or lead iodide in the perovskite, and at the same time, the halogen atoms in the functional groups can effectively fill the anion vacancies in the perovskite lattice. This dual action mechanism can not only passivate the defects in the precursor solution, reduce the hysteresis effect, but also inhibit the segregation of halides, thereby regulating the growth kinetics of the perovskite film, and finally obtaining a light-absorbing layer material with high crystal quality and low defect density, realizing the synergistic improvement of device efficiency and stability.

[0028] In some embodiments of the present invention, the anthraquinone compound is selected from any one or more of 2-chloroanthraquinone, 2-bromoanthraquinone, 2-aminoanthraquinone, 2-anthraquinonesulfonic acid, anthraquinone-2-carbonyl chloride, 1-amino-4-bromoanthraquinone-2-sulfonic acid, 1-oxoanthraquinone, 1-nitroanthraquinone ester, 2-nitroanthraquinone-8-sulfonic acid, 1-nitroanthraquinone-5-sodium sulfonate, 1,5-dinitroanthraquinone, 1,5-diaminoanthraquinone, 1,2-dihydroxy-3-nitroanthraquinone, 1-nitro-2-methylanthraquinone, 1,4-dihydroxyanthraquinone-2-sulfonic acid.

[0029] The process of preparing the lead iodide film in the present invention includes: adding the anthraquinone compound to the lead iodide precursor solution, and then spin-coating on a substrate and annealing.

[0030] The lead iodide precursor solution in the present invention contains inorganic halides commonly used in the art, including but not limited to chlorides, bromides, and iodides. In some embodiments of the present invention, the lead iodide solution further includes rubidium chloride and cesium iodide. In some embodiments of the present invention, the mass ratio of lead iodide, rubidium chloride, cesium iodide, and anthraquinone compound is 695:5.4:7.8:(2-4).

[0031] In some embodiments of the present invention, the spin-coating rate when preparing the lead iodide film is 1500 rpm, the acceleration is 1500 rpm / s, and the spin-coating time is 30 s. In some embodiments of the present invention, the annealing temperature when preparing the lead iodide film is 70 °C, and the annealing time is 1 min.

[0032] The process for preparing the perovskite light-absorbing layer in the present invention is as follows: adding an anthraquinone compound to the perovskite precursor solution, and then spin-coating it on a substrate and annealing.

[0033] The solute in the perovskite precursor solution described in the present invention includes an organic halide of the chemical formula AX type, where A includes one or more of formamidine or methylamine; where X is a halogen element, and the halogen element includes one or more of F, I, Br, and Cl elements. In some embodiments of the present invention, the perovskite precursor solution is formamidine iodide and methylamine chloride. The mass ratio of formamidine iodide, methylamine chloride, and anthraquinone compound is 85.3:14:(2 - 4).

[0034] In some embodiments of the present invention, the spin-coating rate during the preparation of the perovskite light-absorbing layer is 2000 rpm, the acceleration is 2000 rpm / s, and the spin-coating time is 30 s. In some embodiments of the present invention, the annealing temperature during the preparation of the perovskite light-absorbing layer is 150 °C, and the annealing time is 15 min.

[0035] The preparation method described in the present invention further includes cleaning the conductive glass, preparing the electron transport layer, preparing the hole transport layer, and preparing the back electrode.

[0036] The material of the electron transport layer is selected from any one or more of C 60 , PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), TiO2 (titanium oxide), SnO2 (tin oxide), Nb2O5 (niobium oxide).

[0037] The process for preparing the hole transport layer includes: mixing Spiro-OMeTAD, a dopant, a lithium salt, and a cobalt salt and then spin-coating.

[0038] The present invention uses a two-step method to prepare perovskite solar cells, which has the following advantages compared with the one-step preparation process commonly used in the prior art: (1) Facilitating the reaction: Since it has a great relationship with the solution concentration during the dissolution to recrystallization process, the principle of separating inorganic components and organic components is adopted in the process of preparing perovskite thin films by the two-step method, and there is greater flexibility in the selection of components and solutions; (2) Facilitating the action of anthraquinone compounds: For a series of molecules with an anthraquinone skeleton, a better selection range can be provided according to their different solubilities in different solvents; (3) Facilitating crystal growth: The two-step spin-coating method can achieve the controllable growth of perovskite crystals to obtain higher stability and efficiency.

[0039] The present invention also provides a perovskite solar cell prepared by the above preparation method.

[0040] In the present invention, the structure of the perovskite solar cell includes a conductive glass, an electron transport layer, a lead iodide thin film, a perovskite light-absorbing layer, a hole transport layer, and a back electrode.

[0041] The perovskite solar cell prepared by the method of the present invention has excellent electrochemical performance, with a cell efficiency of more than 24% and a storage stability of more than 90%.

[0042] The above is a detailed description of the technical solution of the present invention, and the following are specific examples.

[0043] Example 1

[0044] This example provides a method for preparing a perovskite solar cell, which includes the following steps:

[0045] S1. Clean the conductive glass: Ultrasonically clean the indium tin oxide (ITO) conductive glass with pure water, deionized water, acetone, and ethanol for 20 minutes respectively, and then dry it for standby.

[0046] S2. Prepare the electron transport layer: Use a pipette to take 40 μl of tin oxide (SnO2), and spin-coat a layer of tin oxide (SnO2) thin film on the cleaned indium tin oxide (ITO) conductive glass with a spin coater at a spin rate of 2400 rpm, an acceleration of 2400 rpm / s, and a spin time of 30 s, and then anneal at 150 °C for 15 minutes.

[0047] S3. Prepare the lead iodide thin film: Dissolve 0.695 g of lead iodide, 5.4 mg of rubidium chloride (RbCl), 7.8 mg of cesium iodide (CsI), and 2 mg of anthraquinone compound (i.e., 2-chloroanthraquinone, as shown in Formula 1) together in 1 mL of a mixed solvent (DMF:DMSO volume ratio of 9:1), and then use a pipette to take 40 μl of this solution and spin-coat it on the substrate of the electron transport layer at a spin rate of 1500 rpm, an acceleration of 1500 rpm / s, and a spin time of 30 s, and then anneal at 70 °C for 1 minute.

[0048]

[0049] S4. Prepare the perovskite light-absorbing layer: Dissolve 85.3 mg of formamidinium iodide (FAI) and 14 mg of methylammonium chloride (MACl) together in 1 ml of isopropanol (IPA), and then use a pipette to take 50 μl of this solution and spin-coat it on the lead iodide thin film at a spin rate of 2000 rpm, an acceleration of 2000 rpm / s, and a spin time of 30 s, and then anneal at 150 °C for 15 minutes.

[0050] S5. Preparation of hole transport layer: Dissolve 91.4 mg of 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 35.6 μl of 4-tert-butylpyridine (tBP), 21.5 μl of lithium salt, and 11.4 μl of cobalt salt in 1 ml of chlorobenzene, and spin-coat it on the perovskite light-absorbing layer at a spin-coating rate of 4000 rpm, an acceleration of 2000 rpm / s, and a spin-coating time of 30 s.

[0051] S6. Preparation of back electrode: Evaporate 100 nm of silver (Ag) as the back electrode on the hole transport layer, with a vacuum degree < 1×10 -4 Pa, and the speed is

[0052] Example 2

[0053] Same as Example 1, except that in step S3, the dosage of 2-chloroanthraquinone is 4 mg.

[0054] Example 3

[0055] Same as Example 1, except that in step S3, 2-chloroanthraquinone is not added, and in step S4, 2 mg of 2-chloroanthraquinone is added. After mixing 2-chloroanthraquinone with FAI and MACl, dissolve them in 1 ml of isopropanol (IPA), and then carry out the subsequent operations.

[0056] Example 4

[0057] Same as Example 3, except that the dosage of 2-chloroanthraquinone is 4 mg.

[0058] Example 5

[0059] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the backbone is Formula 2 (2-bromoanthraquinone).

[0060]

[0061] Example 6

[0062] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the backbone is Formula 3 (2-aminoanthraquinone).

[0063]

[0064] Example 7

[0065] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the backbone is Formula 4 (2-anthraquinonesulfonic acid).

[0066]

[0067] Example 8

[0068] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 5 (anthraquinone-2-carbonyl chloride).

[0069]

[0070] Example 9

[0071] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 6 (1-amino-4-bromoanthraquinone-2-sulfonic acid).

[0072]

[0073] Example 10

[0074] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 7 (1-anthraquinone oxide).

[0075]

[0076] Example 11

[0077] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 8 (1-nitroanthraquinone ester).

[0078]

[0079] Example 12

[0080] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 9 (2-nitroanthraquinone-8-sulfonic acid).

[0081]

[0082] Example 13

[0083] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 10 (sodium 1-nitroanthraquinone-5-sulfonate).

[0084]

[0085] Example 14

[0086] Same as Example 1, except that in S3, the molecule with anthraquinone (AQ) as the skeleton has the molecular formula of Formula 11 (1,5-dinitroanthraquinone).

[0087]

[0088] Example 15

[0089] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the skeleton added is Formula 12 (1,5-diaminoanthraquinone).

[0090]

[0091] Example 16

[0092] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the skeleton added is Formula 13 (1,2-dihydroxy-3-nitroanthraquinone).

[0093]

[0094] Example 17

[0095] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the skeleton added is Formula 14 (1-nitro-2-methylanthraquinone).

[0096]

[0097] Example 18

[0098] Same as Example 1, except that in S3, the molecular formula of the molecule with anthraquinone (AQ) as the skeleton added is Formula 15 (1,4-dihydroxyanthraquinone-2-sulfonic acid).

[0099]

[0100] Comparative Example 1

[0101] Same as Example 1, except that 2-chloroanthraquinone is not added in step S3.

[0102] Comparative Example 2

[0103] Same as Example 1, except that the dosage of 2-chloroanthraquinone is 8 mg.

[0104] Effect Example 1 Electrochemical performance test of solar cells

[0105] The solar cell devices prepared in the examples and comparative examples were subjected to electrochemical performance tests to explore their stability and efficiency.

[0106] Test conditions: The open-circuit voltage V measured under 1 sunlight condition OC and short-circuit current J SC, fill factor FF, efficiency PCE; stability is the storage stability efficiency measured after storing the battery in a drying oven (24 °C) for 1500 hours relative to the initial efficiency.

[0107] The electrochemical performance test data of Examples 1-18 and Comparative Examples 1-2 are shown in Table 1. Among them, the J-V characteristic curves of the solar cells in Example 1 and Comparative Example 1 are shown in Figure 1 . The EQE characteristic curves of the solar cell devices obtained in Example 1 and Comparative Example 1 were measured as shown in Figure 2 to verify the accuracy of the test data.

[0108] Table 1

[0109]

[0110]

[0111] It can be seen from Table 1 that in the examples of the present invention, due to the addition of 2-4 mg / mL of anthraquinone compounds during the preparation of lead iodide thin films or perovskite light-absorbing layers, the battery efficiency and storage stability of the battery are significantly improved. In Comparative Example 1, since no anthraquinone compounds were added, both the efficiency and storage stability of the battery decreased significantly. Although anthraquinone compounds were also added in Comparative Example 2, since its concentration exceeded the range defined in the present invention, it would also affect the efficiency and stability of the battery.

[0112] Effect Example 2 Characterization of the passivation performance of anthraquinone compounds

[0113] AFM characterization was performed on the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1, as shown in Figure 3 . It can be seen that compared with Comparative Example 1, after adding anthraquinone compounds in Example 1 of the present invention, the average surface roughness decreased, indicating that anthraquinone compounds can passivate the defects of perovskite, effectively regulate the growth process of perovskite thin films, and thus improve the quality of perovskite thin films.

[0114] SEM characterization was performed on the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1, as shown in Figure 4 . It can be seen that compared with Comparative Example 1, the surface morphology of Example 1 is flatter, with fewer impurities and defects, indicating that after adding anthraquinone compounds in Example 1, the defects in the perovskite precursor solution can be passivated, reducing the strong hysteresis existing in it, and reducing the halide segregation existing inside it, reducing the lead iodide content on the surface of the perovskite thin film, and thus improving the quality of the perovskite thin film, which is beneficial to the improvement of the stability and efficiency of the device.

[0115] Photoluminescence (PL) characterization was performed on the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1, as shown in Figure 5It can be seen that, compared with Comparative Example 1, the peak intensity of Example 1 becomes higher, indicating that its defects are reduced. Furthermore, it shows that anthraquinone compounds have a passivation effect and can passivate the defects of perovskite.

[0116] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limitations on the present invention. The protection scope of the present invention should be defined by the scope of the claims. For those of ordinary skill in the art, several improvements and refinements can be made without departing from the spirit and scope of the present invention, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a perovskite solar cell based on redox dynamic passivation, characterized in that, Comprising: Adding 2 - 4 mg / mL of anthraquinone compounds during the preparation of lead iodide thin films or the preparation of perovskite light - absorbing layers.

2. The preparation method according to claim 1, wherein, The anthraquinone compounds are selected from any one or more of 2 - chloroanthraquinone, 2 - bromoanthraquinone, 2 - aminoanthraquinone, 2 - anthraquinonesulfonic acid, anthraquinone - 2 - carbonyl chloride, 1 - amino - 4 - bromoanthraquinone - 2 - sulfonic acid, 1 - anthraquinone oxide, 1 - nitroanthraquinone ester, 2 - nitroanthraquinone - 8 - sulfonic acid, 1 - nitroanthraquinone - 5 - sodium sulfonate, 1,5 - dinitroanthraquinone, 1,5 - diaminoanthraquinone, 1,2 - dihydroxy - 3 - nitroanthraquinone, 1 - nitro - 2 - methylanthraquinone, 1,4 - dihydroxyanthraquinone - 2 - sulfonic acid.

3. The preparation method according to claim 1 or 2, characterized in that, The process for preparing the lead iodide thin film includes: adding the anthraquinone compound into the lead iodide precursor solution, and then spin - coating it on a substrate and annealing.

4. The preparation method according to claim 1 or 2, characterized in that The process for preparing the perovskite light - absorbing layer includes: adding anthraquinone compounds into the perovskite precursor solution, and then spin - coating it on a substrate and annealing.

5. The preparation method according to claim 4, characterized in that, The solute in the perovskite precursor solution includes an organic halide of the chemical formula AX type, where A includes one or more of formamidine or methylamine; where X is a halogen element, and the halogen element includes one or more of F, I, Br, Cl elements.

6. The preparation method according to claim 1 or 2, characterized in that, The preparation method further includes cleaning the conductive glass, preparing the electron transport layer, preparing the hole transport layer, and preparing the back electrode.

7. The preparation method according to claim 6, characterized in that, The material of the electron transport layer is selected from any one or more of C 60 , PCBM, TiO2, SnO2, and Nb2O5.

8. The preparation method according to claim 6, wherein, The process for preparing the hole transport layer includes: mixing Spiro - OMeTAD, a dopant, a lithium salt, and a cobalt salt and then depositing.

9. A perovskite solar cell prepared by the preparation method according to any one of claims 1 - 8.

10. The perovskite solar cell according to claim 9, characterized in that, The structure of the perovskite solar cell includes a conductive glass, an electron transport layer, a lead iodide thin film, a perovskite light - absorbing layer, a hole transport layer, and a back electrode.

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