Application of a class of D-π-A type passivation molecules with benzotricarbazole as donor in perovskite solar cells

Abstract

The present invention provides a D-π-A type molecule with benzotricarbazole as a donor, and also provides a D-π-A type molecule with benzotricarbazole as a donor as a passivator for use in the passivation of perovskite film defects, wherein the carboxyl group thereon can interact with lead ions, thereby passivating the unbonded lead ions in the lattice and reducing the recombination of photogenerated carriers. Moreover, the photosensitive dye itself contains a large conjugated system, which is beneficial to the transmission of photogenerated carriers in the perovskite, thereby improving the photoelectric conversion efficiency of the device. In addition, the deprotonation of the carboxyl group thereon can passivate the methylamine defects in the perovskite film, and the more alkyl chains in the molecule also improve the hydrophobicity of the perovskite film, effectively improving the water-oxygen stability of the battery. After passivation, the various photoelectric properties of the device are significantly improved, and the photoelectric conversion efficiency (PCE) is increased from 17.31% to 19.84%.

Description

Technical Field

[0001] The invention belongs to the field of perovskite solar cells, and particularly relates to application of a D-π-A type molecule using benzotricarbazole as a donor in the passivation of defects in a perovskite film. Background Art

[0002] The sun is the basis of all life on Earth. Among many renewable energy sources, solar energy has become the focus of scientists' research because of its wide range and not limited by geographical location. The sun contains huge energy, and studying the conversion and utilization of solar energy has become a new trend in the development of future energy. Solar cells are an efficient way to convert solar energy into directly usable electrical energy.

[0003] Today, solar cells have developed to the third generation and are still developing rapidly. Among them, perovskite solar cells are the most promising. They have the characteristics of high light absorption coefficient, long carrier diffusion length, wide light absorption range, and adjustable band gap, which makes them have good application prospects. Perovskite is developing very rapidly. In 2009, when it was applied to dye-sensitized solar cells, the efficiency was only 3.81%. Now, it has achieved a high efficiency of 25.5% when applied to perovskite solar cells.

[0004] Defects in perovskite films affect the photovoltaic parameters of the cell, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF) and PCE. There are four main types of defects in organic-inorganic hybrid perovskite films: (1) some intrinsic point defects. (2) impurities, such as Li from Spiro-OMETAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) + , as well as many defects from other raw materials. (3) Two-dimensional defects, including grain boundaries and surface defects. (4) Three-dimensional defects, such as lead clusters. These defects can cause non-radiative recombination of carriers, which in turn affects the photovoltaic parameters of solar cells. Therefore, it is necessary to select suitable molecules to passivate perovskite films.

[0005] There are two main types of passivation methods: (1) Lewis acids and Lewis bases act as electron acceptors and donors, respectively, and react with uncoordinated halide ions and PbI 3 - (2) Through the anion, cation and uncoordinated halide ion, anti-PbI 3 - 、MA + Vacancies form ionic bonds. Summary of the invention

[0006] In view of the above, the purpose of the present invention is to provide a D-π-A type passivation molecule referred to as AJ206 with significant effect, which is suitable for perovskite films of various compositions. The passivation molecule in the present invention is derived from the published article [ACSAppl.Mater. Interfaces 2020,12,46397-46405]

[0007] The passivation molecule can be used as a passivation material in a NiP-type perovskite solar cell for preparing a passivated perovskite film, comprising the following steps:

[0008] The passivation molecule is first dissolved in an anti-solvent to obtain a passivation molecule solution, and the passivation molecule solution is then spin-coated onto the perovskite film and then annealed to obtain a passivated perovskite film;

[0009] The passivation molecule has a structure shown in Formula I:

[0010]

[0011] Said R1 and R2 are independently the same or different C4-C8 alkyl groups, including n-butyl, isobutyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3, 3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1,1-dimethylpentyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1-ethylpentyl, 2-ethylpentyl, 3-ethylpentyl, 1-propylbutyl, n-octyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 1,1-dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5-dimethylhexyl, 1-ethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 1-propylpentyl, 2-propylpentyl;

[0012] The R3 is a C4-C8 alkyl group different from R1 and R2.

[0013] Furthermore, the anti-solvent is ethyl acetate or chlorobenzene.

[0014] Furthermore, the concentration of the passivation molecule solution is 0.05-2.0 mg / ml.

[0015] Furthermore, the spin coating parameters are as follows: 200-250 μl of the passivation molecule solution is dropped at 16 seconds after starting at 5000 rpm, and the spin coating is performed for 14 seconds.

[0016] Furthermore, the annealing temperature is 100° C. and the annealing time is 50 min.

[0017] Furthermore, the passivation molecule solution is spin-coated onto a Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 or Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 in perovskite films.

[0018] The invention provides a passivated perovskite film obtained by applying a passivation molecule in a perovskite solar cell and used for preparing a perovskite solar cell device.

[0019] The present invention provides a device manufacturing example containing the passivation molecule AJ206 and some test data. By testing and comparing the test data of the passivation molecule AJ206 with different contents, it is concluded that the optimal doping concentration of the passivation molecule AJ206 is 0.1 mg / ml. The following table I shows the various photovoltaic characteristic values ​​of the device at different passivation molecule AJ206 concentrations.

[0020] Table I

[0021]

[0022] The invention prepares a perovskite solar cell device under the optimal concentration of the passivation molecule AJ206. The device consists of a conductive layer, an electron transport layer, a perovskite active layer, a hole transport layer and a metal electrode layer from bottom to top.

[0023] In the above perovskite device, the conductive substrate is glass.

[0024] In the above perovskite device, the electron transport layer material is titanium dioxide (TiO 2 ) film or tin dioxide (SnO 2 ) film.

[0025] In the above perovskite device, the perovskite active layer is made of Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3 (MA:CH 3 NH 3； FA:CH5ClN2) material.

[0026] In the above perovskite device, the hole transport layer is a Spiro-OMeTAD chlorobenzene solution doped with 4-tert-butylpyridine (TBP), lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and FK209 Co(III)TFSI.

[0027] In the above perovskite device, the metal electrode layer material is Ag or Au, with a thickness of about 90 nm.

[0028] The advantages of the present invention are:

[0029] The carboxyl groups on the passivation molecule AJ206 can interact with lead ions, thereby passivating unbonded lead ions in the lattice and reducing their recombination with photogenerated carriers. Moreover, the photosensitizing dye itself contains a large conjugated system, which is beneficial to the transmission of photogenerated carriers in the perovskite, thereby improving the photoelectric conversion efficiency of the device. In addition, the deprotonation of the carboxyl groups on it can passivate the methylamine defects in the perovskite film, and the more alkyl chains in the molecule also improve the hydrophobicity of the perovskite film, effectively improving the water-oxygen stability of the battery. The photoelectric conversion efficiency (PCE) of the passivated device increased from 17.31% to 19.84%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The UV absorption spectra of the perovskite films doped with 0.1 mg / ml AJ206 and undoped AJ206 in the present invention are shown.

[0031] Figure 2 It shows the steady-state fluorescence spectra of the perovskite film doped with 0.1 mg / ml AJ206 and the perovskite film not doped with AJ206 in the present invention.

[0032] Figure 3 The X-ray diffraction patterns of the perovskite films doped with 0.1 mg / ml AJ206 and those without AJ206 in the present invention are shown.

[0033] Figure 4 Scanning electron microscope images of the perovskite film doped with 0.1 mg / ml AJ206 and the perovskite film without AJ206 in the present invention.

[0034] Figure 5 The water contact angle test graph of the perovskite film doped with 0.1 mg / ml AJ206 and the perovskite film not doped with AJ206 in the present invention is shown.

[0035] Figure 6The composition of the present invention doped with 0.1 mg / ml AJ206 and undoped AJ206 is Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 JV curve of perovskite solar cell.

[0036] Figure 7 The composition of the present invention doped with 0.1 mg / ml AJ206 and undoped AJ206 is Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 JV curve of perovskite solar cell. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific embodiments and comparative examples so that those skilled in the art can better understand the present invention. However, the examples described here are only used to explain the present invention, and the present invention is not limited thereto.

[0038] The experimental drugs used in the following examples were all analytically pure reagents and could be used directly unless otherwise specified.

[0039] Example 1

[0040] The manufacturing process of the perovskite solar cell device used in this patent is as follows:

[0041] (1) Treatment method of FTO conductive glass

[0042] Wipe the conductive glass with a dust-free cloth dipped in a detergent solution to preliminarily remove impurities on the glass surface. Then ultrasonically clean it with a detergent solution, deionized water (twice), acetone, and isopropanol for 20 minutes respectively, and blow it dry with a nitrogen spray gun for later use.

[0043] (2) Preparation method of electron transport layer

[0044] The cleaned conductive glass is first treated with an ozone-plasma cleaning machine before use to remove organic impurities on the surface and increase hydrophilicity. 2 The aqueous solution was prepared according to SnO 2 Aqueous solution: deionized water (containing 3.75 mg / ml KCl) = 1:4 (v / v) dilution ratio, then filter with a 0.22 μm polyethersulfone filter. Spin-coat the prepared tin oxide solution on a conductive glass substrate at a speed of 4000 rpm for 30 seconds. Then anneal at 170°C for 30 minutes.

[0045] (3) Preparation method of perovskite layer

[0046] Dissolve 0.1 mg of AJ206 solid powder in 1 ml of ethyl acetate or chlorobenzene and dissolve it in ultrasound. As the concentration increases, the color gradually deepens. After dissolution, set aside for later use. Prepare the perovskite composition of FAI (1M), PbBr in a vacuum glove box. 2 (0.2M), MABr(0.2M), PbI 2 The precursor solution of (1.1M) and CsI (0.06M) was prepared. The solvent was a mixed solution of dimethyl sulfoxide and N,N-dimethylformamide (1:4, v / v). The prepared precursor solution was stirred for more than 4 hours. The perovskite precursor solution was filtered with a 0.22μm polytetrafluoroethylene filter membrane before spin coating. Before preparing the perovskite film, the glass substrate was first placed in a plasma cleaner for at least 3 minutes to enhance the hydrophilicity of the substrate. The perovskite film was prepared by a one-step method. The substrate was placed on a spin coater, 50μl of the precursor solution was dripped, and the spin coating was first performed at 1000rpm for 9s, then at 5000rpm for 30s. After starting at 5000rpm, 230μl of ethyl acetate doped with AJ206 was dripped at 16s, and the spin coating was performed. After the spin coating parameters were supplemented, the spin coating parameters were added. After the end, it was annealed at 100℃ for 50min. After natural cooling, the composition of the black mirror surface was Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 Passivated perovskite films.

[0047] (4) Preparation method of hole transport layer

[0048] Prepare the hole transport layer precursor in a vacuum glove box. The hole transport layer solution is made by dissolving a mixture of SpiroOMeTAD (72.3 mg), t-BP (28.8 μl) and Li-TFSI (17.5 μl) (520 mg Li-TFSI / 1 mL acetonitrile) in 1 mL chlorobenzene and stirring for more than 2 hours. Filter with a 0.22 μm polytetrafluoroethylene filter before use. Take 50 μL of the hole transport layer precursor drop on the surface of the substrate coated with the perovskite film, spin coat at 3000 rpm for 30 seconds, and return at 50 ° C for 5 minutes after the end.

[0049] (5) Preparation method of counter electrode

[0050] After the hole transport layer is spin-coated, a scraper is used to etch the opposite side to scrape out a 3×15 mm blank area, exposing the FTO layer as the negative electrode of the battery. The processed film is neatly placed on the customized mask plate, and the evaporation rate is adjusted to 0.02 nm / s under vacuum conditions (1×10 -4 Pa) Use a vacuum coating machine to evaporate a layer of 80nm thick gold or silver electrode.

[0051] Comparative Example 1

[0052] FTO / SnO 2 / Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 / Spiro-OMeTAD / Ag Devices

[0053] (1) Treatment method of FTO conductive glass

[0054] The method is the same as in Example 1

[0055] (2) Preparation method of electron transport layer

[0056] The method is the same as in Example 1

[0057] (3) Preparation method of perovskite layer

[0058] The method is the same as that of Example 1, except that ethyl acetate without AJ206 doping is used as the anti-solvent, and the other steps are the same.

[0059] (4) Preparation method of hole transport layer

[0060] The method is the same as in Example 1

[0061] (5) Preparation method of counter electrode

[0062] The method is the same as in Example 1

[0063] The perovskite films described in Example 1 and Comparative Example 1 were subjected to UV-visible light absorption tests. The test spectra are shown in FIG. Figure 1 It can be seen that the diffraction peak position of the perovskite film with 0.1 mg / ml AJ206 added is basically the same as that without addition, the absorption intensity is enhanced at a wavelength of 550-750 nm, and the light absorption performance is significantly improved.

[0064] The perovskite films described in Example 1 and Comparative Example 1 were subjected to steady-state fluorescence testing. The test spectra are shown in FIG. Figure 2As shown in Figure 2, the PL intensity increased significantly after AJ206 passivation, indicating that the non-radiative recombination process caused by defects was reduced and the quality of the perovskite film was significantly improved.

[0065] The perovskite films described in Example 1 and Comparative Example 1 were subjected to X-ray diffraction tests, and the test spectra were as follows: Figure 3 As shown in the figure, the perovskite characteristic peak intensity of the perovskite film after passivation with AJ206 is significantly enhanced, and the characteristic peak intensity of lead iodide is significantly reduced. It can be seen that AJ206 passivates the unbonded lead ions in the lattice, reduces their recombination with photogenerated carriers, and improves the quality of the perovskite film.

[0066] The perovskite films described in Example 1 and Comparative Example 1 were tested using a scanning electron microscope. The test spectra are shown in FIG. Figure 4 As shown. It can be seen that the surface of the perovskite film passivated by AJ206 is more dense, the grains are larger, and there are fewer grain boundaries, which helps the perovskite layer to have good contact with the hole layer, promotes hole transport, blocks electrons from entering the hole layer, reduces non-radiative recombination, and helps improve device efficiency.

[0067] The water contact angle of the perovskite film described in Example 1 and Comparative Example 1 was tested. The test results are as follows: Figure 5 As shown in Figure 2, the water contact angle increases from 63° to 89°, which shows that the hydrophobicity of the perovskite film after AJ206 passivation increases, thus significantly improving the humidity stability of the perovskite film.

[0068] The perovskite solar cell device was prepared according to the method of Example 1, and the JV test was carried out under AM 1.5G simulated sunlight. The results are as follows: Figure 6 As shown, it can be seen that the photovoltaic performance of the device after passivation is improved, and the photoelectric conversion efficiency is increased from 17.31% to 19.84%.

[0069] Example 2

[0070] FTO / SnO 2 / Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 / Spiro-OMeTAD / Ag Devices

[0071] (1) Treatment method of FTO conductive glass

[0072] The method is the same as in Example 1

[0073] (2) Preparation method of electron transport layer

[0074] The method is the same as in Example 1

[0075] (3) Preparation method of perovskite layer

[0076] The method is the same as that of Example 1. The difference from Example 1 is that the composition of the perovskite precursor solution is different. Here, the composition is FAI (1 M), PbBr 2 (0.53M), PbI 2 (1.8M) and CsI (0.18M) to obtain a precursor solution with a composition of Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 Passivated perovskite films.

[0077] (4) Preparation method of hole transport layer

[0078] The method is the same as in Example 1

[0079] (5) Preparation method of counter electrode

[0080] The method is the same as in Example 1

[0081] Comparative Example 2

[0082] FTO / SnO 2 / Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 / Spiro-OMeTAD / Ag devices.

[0083] (1) Treatment method of FTO conductive glass

[0084] The method is the same as in Example 1

[0085] (2) Preparation method of electron transport layer

[0086] The method is the same as in Example 1

[0087] (3) Preparation method of perovskite layer

[0088] The method is the same as that of Example 1. The difference from Example 1 is that the composition of the perovskite precursor solution is different. Here, the composition is FAI (1M), PbBr 2 (0.53M), PbI 2 The precursor solutions were AJ206 (1.8 M) and CsI (0.18 M), and the anti-solvent was ethyl acetate without AJ206 doping. The other steps were the same.

[0089] (4) Preparation method of hole transport layer

[0090] The method is the same as in Example 1

[0091] (5) Preparation method of counter electrode

[0092] The method is the same as in Example 1

[0093] The PSCs obtained in Example 2 and Comparative Example 2 were subjected to JV tests under AM 1.5G simulated sunlight. Figure 7 The data of the unpassivated device are as follows: open circuit voltage V OC =1.11V, short circuit current J SC =22.5 mA cm 2 , fill factor FF = 69%, PCE = 17.3%. The data of the AJ206 passivated device are: V OC =1.15V, J SC =23.4 mA cm 2 , FF=72%, PCE=19.3%, both the voltage and photoelectric conversion efficiency are significantly improved.

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Application of a D-π-A type perovskite film defect passivation molecule with benzotricarbazole as a donor in a perovskite solar cell, characterized in that: The passivation molecule can be used as a passivation material in a NiP-type perovskite solar cell for preparing a passivated perovskite film, comprising the following steps: The passivation molecule is first dissolved in an anti-solvent to obtain a passivation molecule solution, and the passivation molecule solution is then spin-coated onto the perovskite film and then annealed to obtain a passivated perovskite film; The passivation molecule has a structure shown in Formula I: The R1 and R2 are independently the same or different C4-C8 alkyl groups, including n-butyl, isobutyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, n-heptyl, methylpentyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1-ethylpentyl, 2-ethylpentyl, 3-ethylpentyl, 1-propylbutyl, n-octyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 1,1-dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5-dimethylhexyl, 1-ethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 1-propylpentyl, 2-propylpentyl; The R3 is a C4-C8 alkyl group different from R1 and R2.

2. The use of the passivation molecule in a perovskite solar cell according to claim 1, characterized in that: The anti-solvent is ethyl acetate or chlorobenzene.

3. The use of the passivation molecule in a perovskite solar cell according to claim 1, characterized in that: The concentration of the passivation molecule solution is 0.05-2.0 mg / ml.

4. The use of the passivation molecule in a perovskite solar cell according to claim 1, characterized in that: The spin coating parameters are as follows: 200-250 μl of the passivation molecule solution is dropped at 16 seconds after starting at 5000 rpm, and the spin coating is performed for 14 seconds.

5. The use of the passivation molecule in a perovskite solar cell according to claim 1, characterized in that: The annealing temperature is 100° C. and the annealing time is 50 min.

6. The use of the passivation molecule in a perovskite solar cell according to claim 1, characterized in that: The passivation molecule solution is spin-coated onto a Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.83 Br 0.17 )3 or Cs 0.15 FA 0.85 PbI 2.55 Br 0.45 in perovskite films.

7. The passivated perovskite film obtained by using the passivation molecules according to claims 1 to 6 in perovskite solar cells is used to prepare perovskite solar cell devices.

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