An organic molecule additive for perovskite solar cells and a preparation method and application thereof

Abstract

The application provides an organic molecule additive for a perovskite solar cell and a preparation method and application thereof. A structural formula of the organic molecule additive is shown in the following; wherein R1 and R2 are each independently selected from any one of -H, -CH3, -OH, -COOH, -SO3H, -F, -Cl, -Br, -I, -O-CH3 or -NH2; and R3 is a pyridyl group. In the organic molecule additive provided by the application, an electron-rich carbonyl group and an electron donor unit -C=N- can be coordinated with Pb 2+ defects existing on the surface of a perovskite thin film, and the spatial configuration of N can increase the steric hindrance of the molecule, which is beneficial to the passivation of the perovskite thin film. In addition, R1 and R2 as substituents can further coordinate with Pb 2+ defects, and improve the film quality of the perovskite thin film. Therefore, the organic molecule additive in combination with the perovskite solar cell can significantly reduce defects and improve the film quality.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to an organic molecular additive for perovskite solar cells, its preparation method, and its application. Background Technology

[0002] With the continuous development of human society, the demand for energy is increasing. Traditional energy sources, such as oil, natural gas, and coal, are non-renewable. Not only are their reserves dwindling, but they also cause significant environmental pollution. Therefore, vigorously developing renewable, green, and clean energy is extremely urgent and important. Solar energy stands out in particular, as it is inexhaustible and does not impact the environment. Its application research has received increasing attention. Developing clean, pollution-free, and abundant solar energy has become a hot topic of research for scientists. Organic-inorganic hybrid perovskite solar cells, due to their significant advantages such as low cost, high conversion efficiency, and suitability for industrial production, have seen their photoelectric conversion efficiency rapidly rise to 26.7% since their introduction in 2009.

[0003] In the fabrication of perovskite solar cells, many factors significantly affect device performance. These include a rapid crystallization rate and numerous defects in the perovskite thin film during fabrication, which can impact carrier transport efficiency and hinder photoelectric conversion efficiency. Additionally, the perovskite surface contains a large number of unbonded Pb atoms. 2+ This is also the main reason for the formation of defects and the impact on film quality.

[0004] Therefore, how to reduce defects in perovskite thin films and improve their quality, thereby enhancing the photoelectric conversion efficiency and stability of devices, is an urgent technical problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an organic molecular additive for perovskite solar cells, its preparation method, and its applications. This invention provides a multifunctional organic molecular additive that, when used in perovskite solar cells, allows both electron-rich carbonyl groups and electron-donating units (-C=N-) to react with Pb present on the perovskite film surface. 2+ Defect bonding, coupled with the increased steric hindrance of N due to its spatial configuration, facilitates passivation of perovskite films. Furthermore, R1 and R2, as substituents, can further bind with Pb. 2+ The organic molecular additive coordinates and passivates defects in the perovskite film, thereby improving its uniformity. Therefore, this organic molecular additive can significantly reduce defects in perovskite films, improve their quality, and ultimately enhance the photoelectric conversion efficiency and stability of the device.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an organic molecular additive for perovskite solar cells, the structural formula of which is shown below:

[0008]

[0009] R1 and R2 are each independently selected from any one of -H, -CH3, -OH, -COOH, -SO3H, -F, -Cl, -Br, -I, -O-CH3 or -NH2; R3 is pyridyl.

[0010] This invention provides a multifunctional organic molecular additive for use in perovskite solar cells, where the electron-rich carbonyl group and the electron donor unit -C=N- can react with Pb present on the surface of the perovskite film. 2+ Defect bonding, coupled with the increased steric hindrance of N due to its spatial configuration, facilitates passivation of perovskite films. Furthermore, R1 and R2, as substituents, can further bind with Pb. 2+ The organic molecular additive coordinates and passivates defects in the perovskite film, thereby improving its uniformity. Therefore, this organic molecular additive can significantly reduce defects in perovskite films, improve their quality, and ultimately enhance the photoelectric conversion efficiency and stability of the device.

[0011] Preferably, R1 and R2 are not both -H.

[0012] Preferably, R1 and R2 are each independently selected from any one of -OH, -COOH, -SO3H, -F, -Cl, -Br or -I.

[0013] In this invention, hydroxyl, carboxyl, or sulfonyl groups, etc., can further react with Pb. 2+ Coordination significantly reduces vacancy defects in perovskite films, effectively passivating defect sites. Meanwhile, halogen-terminated groups can fill halogen vacancies in perovskite, enhancing the bonding with the perovskite film through ionic bonds and improving the uniformity of the perovskite film.

[0014] Preferably, the structural formula of the organic molecular additive is selected from any one of structural formula I, structural formula II, or structural formula III, as shown below:

[0015]

[0016]

[0017] In a second aspect, the present invention provides a method for preparing an organic molecular additive as described in the first aspect, the method comprising the following steps:

[0018] The first reactant, the second reactant, the metal catalyst, the ligand, the strong base, and the organic solvent are mixed and reacted to obtain the organic molecular additive.

[0019] The chemical formula of the first reactant is:

[0020] The structural formula of the second reactant is as follows:

[0021] R1 and R2 are each independently selected from any one of -H, -CH3, -OH, -COOH, -SO3H, -F, -Cl, -Br, -I, -O-CH3 or -NH2.

[0022] In this invention, the metal catalyst plays a catalytic role in the reaction; the ligand can coordinate with the metal catalyst, enabling the metal catalyst to participate in the reaction in a more suitable active state, preventing catalyst deactivation or decomposition, thereby improving the efficiency and selectivity of the reaction; the strong base plays an auxiliary catalytic role.

[0023] Preferably, the first reactant is selected from any one of 2-(4-bromobenzoyl)pyridine, (4-bromophenyl)(pyridin-3-yl)methyl ketone, or (4-bromophenyl)(pyridin-4-yl)methyl ketone.

[0024] Preferably, the metal catalyst comprises palladium acetate.

[0025] Preferably, the ligand comprises tritert-butylphosphine tetrafluoroborate.

[0026] Preferably, the strong base includes sodium tert-butoxide.

[0027] Preferably, the organic solvent includes toluene. For example, it could be anhydrous toluene, etc.

[0028] Preferably, the reaction temperature is 110-120°C, for example, 110°C, 115°C or 120°C.

[0029] In this invention, a suitable reaction temperature helps the reaction to proceed completely. If the temperature is too low, the reaction will not be complete, and if the temperature is too high, the organic solvent will evaporate, resulting in an incomplete reaction. Moreover, the evaporated organic solvent gas is harmful to the human body.

[0030] Preferably, the reaction time is 20-30 hours, for example, 20 hours, 24 hours, 25 hours, 26 hours, or 30 hours.

[0031] Preferably, the preparation method includes the following steps:

[0032] Take a sealed tube, add the first reactant, the second reactant, the metal catalyst, the ligand and the strong base, remove the air from the tube and purge with an inert gas, then add the organic solvent, and stir the reaction at 110-120℃ for 20-30 h; after the reaction is complete, extract the product, purify it, and obtain the organic molecular additive.

[0033] Preferably, the inert gas includes nitrogen.

[0034] Preferably, the extractant for extracting the product includes ethyl acetate.

[0035] Preferably, the purification step includes:

[0036] The solution was purified by silica gel column chromatography using a mixture of ethyl acetate and n-hexane as the eluent.

[0037] Thirdly, the present invention provides an application of the organic molecular additive as described in the first aspect in perovskite solar cells, the method of application comprising the following steps:

[0038] A first carrier transport layer is formed on a transparent conductive substrate.

[0039] A perovskite precursor solution containing organic molecular additives is coated onto the first carrier transport layer, and then annealed to form a perovskite thin film.

[0040] A second carrier transport layer and an electrode layer are sequentially formed on the perovskite thin film to obtain the perovskite solar cell.

[0041] Preferably, in the perovskite precursor solution containing organic molecular additives, the molar ratio of perovskite precursor to organic molecular additives is 100:(0.01-2), for example, it can be 100:0.01, 100:0.05, 100:0.1, 100:0.5, 100:1, 100:1.5 or 100:2, etc., preferably 100:(0.1-1).

[0042] In this invention, the appropriate amount of organic molecular additives is beneficial for achieving efficient passivation of the perovskite layer. Too little additive will result in poor passivation effect, while too much additive may cause organic molecules to agglomerate in the perovskite film, forming new charge carrier recombination centers, thereby affecting battery efficiency.

[0043] Preferably, the perovskite precursor has the general chemical formula ABX3, wherein the A-site cation includes at least one of cesium ion, rubidium ion, formamidinium ion and methylamine ion, the B-site cation includes at least one of lead ion, tin ion and germanium ion, and X is a halide ion.

[0044] Preferably, the method for preparing the perovskite precursor solution containing organic molecular additives includes:

[0045] A perovskite precursor mother liquor is provided, and then the organic molecular additive is added to obtain a perovskite precursor solution containing the organic molecular additive.

[0046] Preferably, the solvent of the perovskite precursor mother liquor includes any one or a combination of at least two of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), 1,3-dimethyl-2-imidazolinone (DMI), dimethylacetamide (DMAC), N,N-dimethylpropenylurea (DMPU), acetonitrile (ACN), or 2-mercaptoethanol (ME).

[0047] Preferably, the coating method includes any one of spin coating, blade coating, or application coating.

[0048] Preferably, the coating method is spin coating, wherein the spin coating rate is 4000-6000 rpm, for example, 4000 rpm, 5000 rpm or 6000 rpm, the spin coating time is 40-60 s, for example, 40 s, 50 s or 60 s, and the acceleration of the spin coating rate is 800-1200 rpm / s, for example, 800 rpm / s, 900 rpm / s, 1000 rpm / s, 1100 rpm / s or 1200 rpm / s.

[0049] Preferably, the annealing temperature is 100-150℃, for example, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, and the annealing time is 15-30min, for example, 15min, 20min, 25min or 30min.

[0050] In this invention, the annealing temperature is mainly related to the crystallization and film formation of perovskite. If the temperature is too low, the solvents that dissolve the perovskite (such as DMF and DMSO) cannot be completely removed, resulting in poor film formation. If the temperature is too high, since perovskite is a material that is sensitive to high temperatures, it may decompose and affect film formation.

[0051] Preferably, the thickness of the perovskite film is 300-700 nm, for example, it can be 300 nm, 400 nm, 500 nm, 600 nm or 700 nm.

[0052] Preferably, the charges transported by the first carrier transport layer and the second carrier transport layer are of opposite polarity.

[0053] Preferably, the material of the first carrier transport layer is a p-type semiconductor, and the material of the second carrier transport layer is an n-type semiconductor.

[0054] For example, the p-type semiconductor can be any one or more of the following materials: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), 4-butyl-N,N-diphenylaniline homopolymer (Ploy-TPD), polyvinylcarbazole (PVK), CuI, CuSCN, (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz) and its derivatives.

[0055] For example, an n-type semiconductor may be a C-type semiconductor. 60 One or more of the following materials: BCP, PCBM, TiO2, SnO2, ZnO, or ZnO-ZnS.

[0056] Preferably, the material of the electrode layer includes any one of Au, Ag, Al, Cu or C.

[0057] Preferably, an interface passivation layer is further disposed between the perovskite thin film and the second carrier transport layer, and the material of the interface passivation layer includes phenylethyl iodide.

[0058] Preferably, the thickness of the interface passivation layer is 1-3 nm, for example, it can be 1 nm, 2 nm or 3 nm.

[0059] Preferably, the method for preparing the interface passivation layer includes spin coating.

[0060] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] This invention provides a multifunctional organic molecular additive for use in perovskite solar cells, where the electron-rich carbonyl group and the electron donor unit -C=N- can react with Pb present on the surface of the perovskite film. 2+ Defect bonding, coupled with the increased steric hindrance of N due to its spatial configuration, facilitates passivation of perovskite films. Furthermore, R1 and R2, as substituents, can further bind with Pb. 2+The organic molecular additive coordinates and passivates defects in the perovskite film, thereby improving its uniformity. Therefore, this organic molecular additive can significantly reduce defects in perovskite films, improve their quality, and ultimately enhance the photoelectric conversion efficiency and stability of the device. Attached Figure Description

[0063] Figure 1 These are XRD comparison images of the perovskite thin films provided in Example 1 and Comparative Example 1 of the present invention.

[0064] Figure 2 The ultraviolet spectra of the perovskite thin films provided in Example 1 and Comparative Example 1 of the present invention are shown.

[0065] Figure 3 The photoluminescence comparison curves of the perovskite thin films provided in Example 1 and Comparative Example 1 of the present invention are shown.

[0066] Figure 4 The fluorescence lifetime spectra of the perovskite thin films provided in Example 1 and Comparative Example 1 of this invention are shown.

[0067] Figure 5 The JV comparison curves are for the perovskite solar cells provided in Example 1 and Comparative Example 1 of the present invention, respectively. Detailed Implementation

[0068] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0069] Example 1

[0070] This embodiment provides an organic molecular additive for perovskite solar cells, the structural formula of which is shown below:

[0071] In this case, both R1 and R2 are -OH.

[0072] This embodiment also provides a method for preparing the above-mentioned organic molecular additive, including the following steps:

[0073] (a) Take a dry 100 mL sealed tube and add (4-bromophenyl)(pyridin-3-yl) methyl ketone (2 g, 7.6 mmol), substance I (7.6 mmol), palladium acetate (0.085 g, 5 mol% (based on (4-bromophenyl)(pyridin-3-yl) methyl ketone), tritert-butylphosphine tetrafluoroborate (0.33 g, 1.14 mmol) and sodium tert-butoxide (1.5 g, 15 mmol).

[0074] The structural formula of substance I is: In this case, both R1 and R2 are -OH.

[0075] (b) After purging the air from the sealed tube, the sealed tube was purged with nitrogen. This process was repeated three times. Then, 40 mL of anhydrous toluene was added, and the mixture was stirred at 115 °C for 24 h. After the reaction was completed, the toluene was removed under reduced pressure, and the product was extracted with ethyl acetate to obtain a mixed product (containing ethyl acetate, the extracted product, and the incompletely removed toluene). The mixed product was concentrated under reduced pressure. Finally, the mixed product was purified by silica gel column chromatography using ethyl acetate / n-hexane (volume ratio = 1:1) as the eluent to obtain the organic molecular additive.

[0076] This embodiment also provides the application of the above-mentioned organic molecular additives in perovskite solar cells, and the method of application includes the following steps:

[0077] (1) Clean the FTO conductive glass, specifically by ultrasonic cleaning with detergent, deionized water, acetone and anhydrous ethanol respectively, and then drying it with a nitrogen gun; wherein the ultrasonic cleaning power is 100Hz and the ultrasonic cleaning time is 15min.

[0078] (2) A hole transport layer is prepared on FTO conductive glass by spin coating. The specific steps include:

[0079] A hole transport layer solution with a concentration of 0.5 mg / mL, prepared from [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), was dropped onto an FTO conductive glass substrate and spin-coated at 3000 rpm for 30 s. The substrate was then annealed at 100 °C for 10 min to obtain a hole transport layer with a thickness of 2 nm.

[0080] (3) A perovskite thin film is prepared on the upper surface of the hole transport layer. The specific steps include:

[0081] CsI ​​(108.33 mg), FAI (1218.34 mg), MAI (132.50 mg), PbI2 (4033.76 mg), and MACl (83.27 mg) were added to a mixed solvent containing DMF (4200 μL) and DMSO (840 μL), and stirred thoroughly for more than 12 hours to obtain a 1.67 mol / L perovskite precursor mother liquor with the chemical formula CsI. 0.05 MA 0.1 FA 0.85 PbI3;

[0082] 0.042 mol of the above-mentioned organic molecular additive was added to the perovskite precursor mother liquor to obtain a perovskite precursor solution containing the organic molecular additive. Then, the perovskite precursor solution was spin-coated onto the hole transport layer by spin coating at a speed of 5000 rpm for 50 s with an acceleration of 1000 rpm / s. At the 35th second of spin coating, 200 μL of chlorobenzene was added dropwise as an anti-solvent. After spin coating, the film was annealed at 120 °C for 15 min to obtain a perovskite film with a thickness of 550 nm.

[0083] In the perovskite precursor solution containing organic molecular additives, the molar ratio of perovskite precursor to organic molecular additives is 100:0.5.

[0084] (4) An interface passivation layer is prepared on the upper surface of the perovskite film. The specific steps include:

[0085] 150 μL of 3 mg / mL phenylethyl iodide (isopropanol as solvent) solution was spin-coated onto a perovskite film at a spin-coating rate of 4000 rpm for 40 s. The film was then annealed at 100 °C for 10 min to obtain an interface passivation layer with a thickness of 2 nm.

[0086] (5) Fabricating an electron transport layer on the interface passivation layer, the specific steps of which include:

[0087] A 20nm thick C layer was deposited on the interface passivation layer using vacuum evaporation. 60 The layer, the vapor deposition is carried out under a vacuum of 5×10 -4 The deposition was carried out under Pa conditions, with a evaporation rate of [missing information].

[0088] Vacuum evaporation deposition method, in C 60 A copper bath (BCP) layer with a thickness of 8 nm is deposited on the layer by vapor deposition at a vacuum degree of 5 × 10⁻⁶. -4 The deposition was carried out under Pa conditions, with a evaporation rate of [missing information].

[0089] (6) Fabricating an electrode layer on the electron transport layer, the specific steps of which include:

[0090] In a metal evaporation chamber, a 100 nm thick silver electrode is formed on the surface of the copper bath layer using a thermal evaporation process; wherein the vacuum degree of the evaporation chamber is 5 × 10⁻⁶. -4 Pa, evaporation rate is

[0091] Example 2

[0092] The difference between this embodiment and Example 1 is that the (4-bromophenyl)(pyridin-3-yl) methyl ketone and substance I are replaced in step (a), so that the organic molecular additive provided in this embodiment has the following structural formula:

[0093] Where R1 is -COOH and R2 is -H.

[0094] The remaining preparation methods and parameters are consistent with those in Example 1.

[0095] Example 3

[0096] The difference between this embodiment and Example 1 is that the (4-bromophenyl)(pyridin-3-yl) methyl ketone and substance I are replaced in step (a), so that the organic molecular additive provided in this embodiment has the following structural formula:

[0097] In this case, both R1 and R2 are -Br.

[0098] The remaining preparation methods and parameters are consistent with those in Example 1.

[0099] Example 4

[0100] The difference between this embodiment and Embodiment 1 is that substance I in step (a) is replaced, so that the organic molecular additive provided in this embodiment has the following structural formula:

[0101] Where R1 is -Cl and R2 is -H.

[0102] The remaining preparation methods and parameters are consistent with those in Example 1.

[0103] Example 5

[0104] The difference between this embodiment and Example 1 is that the (4-bromophenyl)(pyridin-3-yl) methyl ketone and substance I are replaced in step (a), so that the organic molecular additive provided in this embodiment has the following structural formula:

[0105] Where R1 is -CH3 and R2 is -H.

[0106] The remaining preparation methods and parameters are consistent with those in Example 1.

[0107] Example 6

[0108] The difference between this embodiment and Example 1 is that the (4-bromophenyl)(pyridin-3-yl) methyl ketone and substance I are replaced in step (a), so that the organic molecular additive provided in this embodiment has the following structural formula:

[0109] Where R1 is -O-CH3 and R2 is -H.

[0110] The remaining preparation methods and parameters are consistent with those in Example 1.

[0111] Example 7

[0112] The difference between this embodiment and embodiment 1 is that the amount of organic molecular additive added in step (3) is adjusted to 0.84 mmol, so that the molar ratio of perovskite precursor to organic molecular additive is 100:0.01.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Example 8

[0115] The difference between this embodiment and embodiment 1 is that the amount of organic molecular additive added in step (3) is adjusted to 0.168 mol, so that the molar ratio of perovskite precursor to organic molecular additive is 100:2.

[0116] The remaining preparation methods and parameters are consistent with those in Example 1.

[0117] Example 9

[0118] The difference between this embodiment and embodiment 1 is that the amount of organic molecular additive added in step (3) is adjusted to 0.42 mmol, so that the molar ratio of perovskite precursor to organic molecular additive is 100:0.005.

[0119] The remaining preparation methods and parameters are consistent with those in Example 1.

[0120] Example 10

[0121] The difference between this embodiment and embodiment 1 is that the amount of organic molecular additive added in step (3) is adjusted to 0.421 mol, so that the molar ratio of perovskite precursor to organic molecular additive is 100:5.

[0122] The remaining preparation methods and parameters are consistent with those in Example 1.

[0123] Comparative Example 1

[0124] The difference between this comparative example and Example 1 is that no organic molecular additives are added to the perovskite precursor mother liquor in step (3).

[0125] The remaining preparation methods and parameters are consistent with those in Example 1.

[0126] Figure 1The XRD patterns of the perovskite films provided in Example 1 and Comparative Example 1 are shown. As can be seen from the figures, the XRD diffraction peak positions of the perovskite films without organic additive treatment and those treated with organic additives are the same, and there are no other impurity peaks, indicating that the organic additives have not entered the perovskite lattice. Furthermore, the figures also show a significant decrease in the relative height of the PbI2 diffraction peak in the treated perovskite film, further indicating that the pyridine and ketone groups, as well as the new substituent hydroxyl groups in the organic additives, can bond with the unbonded Pb on the perovskite surface. 2+ Coordination passesivates lead defects on the surface and reduces non-radiative recombination.

[0127] Figure 2 The UV spectra of the perovskite films provided in Example 1 and Comparative Example 1 are shown. As can be seen from the figures, the absorption peaks of the perovskite films treated with organic molecular additives show a slight red shift. This is mainly because the electron-rich ketone groups and pyridines contained in the organic molecular additives can react with Pb in the perovskite. 2+ This combination reduces defects and effectively promotes the crystallization of perovskite films, resulting in larger sizes of the final perovskite films. Figure 3 The photoluminescence curves of the perovskite films provided in Example 1 and Comparative Example 1 are shown. As can be seen from the figure, the emission peak of the perovskite film after treatment with organic molecular additives is significantly enhanced. Figure 4 The fluorescence lifetime spectra of the perovskite films provided in Example 1 and Comparative Example 1 are shown. As can be seen from the figures, the fluorescence lifetime of the perovskite films treated with organic molecular additives is significantly improved. All of these indicate that the perovskite films treated with organic molecular additives have fewer defects, and also demonstrate that the perovskite film formation quality is higher.

[0128] Figure 5 The JV comparison curves of the perovskite solar cells provided in Example 1 and Comparative Example 1 are shown. As can be seen from the figure, the perovskite solar cells treated with organic molecular additives have significantly improved open-circuit voltage, short-circuit current, fill factor and photoelectric conversion efficiency.

[0129] Comparative Example 2

[0130] The difference between this comparative example and Example 1 is that the organic molecular additive added to the perovskite precursor mother liquor in step (3) has the following structural formula:

[0131] In this case, both R1 and R2 are -Br.

[0132] The remaining preparation methods and parameters are consistent with those in Example 1.

[0133] Comparative Example 3

[0134] The difference between this comparative example and Example 1 is that, in step (3), an equal amount of substance of perovskite precursor mother liquor was added.

[0135] The remaining preparation methods and parameters are consistent with those in Example 1.

[0136] Performance testing

[0137] The photoelectric performance of the perovskite solar cells provided in the above embodiments and comparative examples was tested under the following conditions: AM1.5, 1000 W / m 2 , 25±2℃.

[0138] The test results are shown in Table 1.

[0139] Table 1

[0140]

[0141]

[0142] analyze:

[0143] As shown in Table 1, the present invention provides a multifunctional organic molecular additive that, when used in perovskite solar cells, can significantly reduce defects in perovskite films, improve the quality of perovskite films, and significantly enhance the open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency of perovskite solar cells.

[0144] As can be seen from the comparison between Example 1 and Examples 9-10, if the concentration of the organic molecular additive is too low, the passivation groups in the additive will decrease, and the lead defects in the perovskite film cannot be effectively passivated, resulting in poor film stability and decreased battery efficiency; if the concentration of the organic molecular additive is too high, new carrier recombination centers may be formed in the perovskite film, affecting battery efficiency.

[0145] As can be seen from the comparison between Example 1 and Comparative Example 1, if the perovskite thin film is not subjected to defect passivation treatment, the open-circuit voltage, short-circuit current, fill factor and photoelectric conversion efficiency of the perovskite solar cell are all poor.

[0146] As can be seen from the comparison between Example 1 and Comparative Example 2, if pyridine is not present in the organic molecular additive, the passivation effect of the organic molecular additive on the perovskite film is poor and cannot play a significant improvement role.

[0147] As can be seen from the comparison between Example 1 and Comparative Example 3, when the organic molecular additive is added in two parts, the two molecules may not be able to exert their effects simultaneously due to the interaction between the molecules, resulting in poor performance of the perovskite solar cell.

[0148] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An organic molecular additive for perovskite solar cells, characterized in that, The structural formula of the organic molecular additive is shown below: R1 and R2 are each independently selected from any one of -H, -CH3, -OH, -COOH, -SO3H, -F, -Cl, -Br, -I, -O-CH3 or -NH2; R3 is pyridyl.

2. The organic molecular additive according to claim 1, characterized in that, R1 and R2 are each independently selected from any one of -OH, -COOH, -SO3H, -F, -Cl, -Br or -I.

3. The organic molecular additive according to claim 1 or 2, characterized in that, The structural formula of the organic molecular additive is selected from any one of structural formula I, structural formula II, or structural formula III, as shown below:

4. A method for preparing an organic molecular additive as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: The first reactant, the second reactant, the metal catalyst, the ligand, the strong base, and the organic solvent are mixed and reacted to obtain the organic molecular additive. The chemical formula of the first reactant is: The structural formula of the second reactant is as follows: R1 and R2 are each independently selected from any one of -H, -CH3, -OH, -COOH, -SO3H, -F, -Cl, -Br, -I, -O-CH3 or -NH2.

5. The preparation method according to claim 4, characterized in that, The first reactant is selected from any one of 2-(4-bromobenzoyl)pyridine, (4-bromophenyl)(pyridin-3-yl)methyl ketone, or (4-bromophenyl)(pyridin-4-yl)methyl ketone; Preferably, the metal catalyst comprises palladium acetate; Preferably, the ligand comprises tritert-butylphosphine tetrafluoroborate; Preferably, the strong base includes sodium tert-butoxide; Preferably, the organic solvent includes toluene; Preferably, the reaction temperature is 110-120°C; Preferably, the reaction time is 20-30 hours.

6. The application of an organic molecular additive as described in any one of claims 1-3 in perovskite solar cells, characterized in that, The method of application includes the following steps: A first carrier transport layer is formed on a transparent conductive substrate; A perovskite precursor solution containing organic molecular additives is coated onto the first carrier transport layer, and then annealed to form a perovskite film. A second carrier transport layer and an electrode layer are sequentially formed on the perovskite thin film to obtain the perovskite solar cell.

7. The application according to claim 6, characterized in that, In the perovskite precursor solution containing organic molecular additives, the molar ratio of perovskite precursor to organic molecular additives is 100:(0.01-2), preferably 100:(0.1-1). Preferably, the perovskite precursor has the general chemical formula ABX3, wherein the A-site cation includes at least one of cesium ion, rubidium ion, formamidinium ion and methylamine ion, the B-site cation includes at least one of lead ion, tin ion and germanium ion, and X is a halide ion.

8. The application according to claim 6 or 7, characterized in that, Methods for preparing perovskite precursor solutions containing organic molecular additives include: A perovskite precursor mother liquor is provided, and then the organic molecular additive is added to obtain a perovskite precursor solution containing the organic molecular additive. Preferably, the solvent of the perovskite precursor mother liquor includes any one or a combination of at least two of N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolinone, dimethylacetamide, N,N-dimethylpropenylurea, acetonitrile, or 2-mercaptoethanol.

9. The application according to any one of claims 6-8, characterized in that, The coating method includes any one of spin coating, blade coating, or application coating. Preferably, the coating method is spin coating, wherein the spin coating rate is 4000-6000 rpm, the spin coating time is 40-60 s, and the acceleration of the spin coating rate is 800-1200 rpm / s. Preferably, the annealing temperature is 100-150℃ and the annealing time is 15-30 min; Preferably, the thickness of the perovskite film is 300-700 nm.

10. The application according to any one of claims 6-9, characterized in that, The charges transported by the first carrier transport layer and the second carrier transport layer are of opposite electrical properties; Preferably, the material of the first carrier transport layer is a p-type semiconductor, and the material of the second carrier transport layer is an n-type semiconductor; Preferably, the material of the electrode layer includes any one of Au, Ag, Al, Cu or C.

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