Defect passivation material based on asymmetric dipole structure and application thereof

Abstract

This invention belongs to the field of perovskite solar cell technology, specifically a defect passivation material based on an asymmetric dipole structure and its application. The defect passivation material of this invention has an asymmetric dipole structure. In its general formula, the two terminal cation groups are an ammonium cation group and an alkylated A cation group, connected by a carbon chain or aromatic ring; B is a neutralizing anionic group, and the A cation represents elements such as nitrogen, phosphorus, sulfur, selenium, and oxygen; B can be independently selected from fluoride ions, chloride ions, bromide ions, iodide ions, etc. The defect passivation material of this invention can be applied to the field of solar cell technology, including perovskite solar cells and multi-junction tandem solar cells. The defect passivator of this invention has multiple functions: effectively passivating energy level defects at grain boundaries and interfaces, inhibiting ion migration behavior, and simultaneously imparting certain hydrophobic properties to the thin film surface, thereby synergistically improving the long-term stability of the interface under humid and hot environments.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a defect passivation material based on an asymmetric dipole structure and its application as a defect passivation layer in perovskite-based tandem solar cells. Background Technology

[0002] Perovskite solar cells, as an emerging third-generation photovoltaic technology, utilize a perovskite photoactive layer with an ABX3 lattice structure as their core. They possess excellent photoelectric properties such as tunable bandgap, high light absorption coefficient, low exciton binding energy, and fast charge migration rate. Multi-junction tandem photovoltaic devices based on perovskite materials exhibit high theoretical photoelectric conversion efficiencies. For example, the theoretical efficiency of perovskite / perovskite tandem solar cells is greater than 45%, perovskite / silicon tandem solar cells are greater than 45%, and perovskite / perovskite / silicon triple-junction solar cells are greater than 50%, far exceeding the current theoretical upper limit of 29.4% for commercial silicon solar cells. This makes them a promising candidate for breaking through the current photovoltaic efficiency bottleneck and achieving technological innovation. Furthermore, perovskite solar cells offer advantages such as solution-based fabrication, low raw material costs, and flexibility, showing broad prospects in emerging application scenarios such as next-generation building-integrated photovoltaics, vehicle-mounted photovoltaics, and space photovoltaics.

[0003] In the fabrication of perovskite solar cells, the rapid low-temperature crystallization process often leads to numerous intrinsic defects on the perovskite's interior and surface, including ion vacancy defects, antisite defects, and dangling bond defects. These defects act as carrier trapping centers, resulting in undesirable nonradiative recombination of electrons and holes, causing energy loss and reducing device conversion efficiency. Furthermore, the presence of interface and bulk defects exacerbates ion migration. Simultaneously, under the influence of external moisture and oxygen, interfacial chemical reactions occur at the defect sites, further disrupting the material's crystal structure and accelerating perovskite degradation, thereby reducing the long-term operational stability of the device. Therefore, defect passivation technology is a key technique for achieving high-efficiency and stable perovskite solar cells.

[0004] Currently, numerous surface passivation technologies are used to mitigate interface defects and suppress nonradiative recombination at the interface. Mainstream passivating agents include organic molecular passivating agents, inorganic salt passivating agents, and low-dimensional perovskite passivating agents. Organic ammonium salts, especially the widely used ethylenediamine (EDAI) series, are typical long-chain diammonium salt passivating agents, exhibiting effective chemical coordination and field-effect passivation effects. Furthermore, organic ammonium salts can also effectively regulate carrier transport and separation by forming unique gradient band structures through the formation of low-dimensional perovskites (1D, 2D, etc.). However, in widely used 2D / 3D heterostructures, low-dimensional perovskites suffer from uncontrollable crystal orientation and energy level mismatch, leading to charge recombination channels, hindering charge transport, and compromising long-term stability. Although these passivating agents can improve the photoelectric performance of perovskite solar cells, their applicability is limited to specific perovskite compositions, restricting their reproducibility and universality. Another key issue is that high-efficiency passivating organic ammonium salts often face passivation failure under photothermal aging. Deprotonation and interfacial desorption of amino ligands can lead to interfacial passivation failure, impairing the long-term operational stability of devices. For example, widely used passivating agents such as phenylethylamine (PEA) exhibit desorption under photothermal stress. Furthermore, amino passivating agents also face protonation under photothermal stress. Therefore, developing a novel passivating agent that can universally and synergistically repair multiple interfacial defects while also possessing good process adaptability is of significant scientific and application value for promoting the industrialization of perovskite multi-junction tandem solar cells. Summary of the Invention

[0005] To address the shortcomings of existing passivation technologies, this invention provides a defect passivation material based on an asymmetric dipole structure and its application in perovskite multijunction tandem solar cells, aiming to solve the problems of photothermal instability and insufficient passivation of existing defect passivation agents.

[0006] The defect passivation material based on an asymmetric dipole structure provided by this invention has an asymmetric dipole structure, and its general chemical formula is:

[0007] ;

[0008] (I)

[0009] In the formula, the two terminal cationic groups are an ammonium cationic group and an alkylated A cationic group, respectively, connected by a carbon chain or an aromatic ring; n is an integer from 1 to 20, and B is an anionic group that neutralizes the charge.

[0010] The A cation represents elements such as nitrogen, phosphorus, sulfur, selenium, and oxygen.

[0011] The group represented by X can be independently selected from: hydrogen atom (H), methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), butyl (-CH2CH2CH2CH3) and other alkyl, phenyl, benzyl, naphthyl, anthracene, phenanthrene, pyrene, thiophene, selenophenol, furanyl, pyrrolyl, pyridyl, indolyl, imidazolyl, thiazolyl, pyrimidinyl, cycloheptyl, cyclohexyl, cyclopentyl, cyclobutyl, cyclopropyl, cyclopentenyl, cyclopentadienyl.

[0012] The anionic group represented by B can be independently selected from: fluoride ions (F... - ), chloride ions (Cl) - ), bromide ions (Br) - ), iodide ions (I - ), thiocyanate (SCN) - ), cyanate (OCN) - ), cyanide (CN) - ), hexafluorophosphate ([PF6]) - ), tetrafluoroborate ([BF4]) - ), perrhenate ([ReO4]) - ), nitrate ([NO3]) - ), formate (HCOO) - Acetate (CH3COO) - ), trifluoroacetate (CF3COO) - ), Methylsulfonate (CH3SO3) - ), trifluoromethanesulfonate (CF3SO3) - ), bis(trifluoromethanesulfonyl)([N(SO2CF3)2) - ).

[0013] More preferably, the asymmetric dipole defect passivating agent material is any one of the following compounds 1-35:

[0014] .

[0015] The present invention also provides that the asymmetric dipole defect passivation material can be applied to the field of solar cell technology, including perovskite solar cells and their multijunction tandem solar cells.

[0016] In the perovskite solar cell described above, this passivating agent material can be passivated and processed by spin coating, inkjet printing, vacuum evaporation, dip coating or molecular beam evaporation. It can be applied to the passivation treatment of the perovskite buried interface (perovskite / hole transport layer) and the perovskite upper interface (perovskite / electron transport layer), with a thickness of 1 to 20 nm, preferably 1 to 10 nm.

[0017] The present invention also provides the application of the molecular passivation material with the asymmetric dipole structure in perovskite-based tandem solar cells.

[0018] Compared with existing perovskite defect passivating agents, the technical features of this invention are as follows:

[0019] (1) Excellent photothermal stability: In traditional perovskite solar cell passivation materials, organic ammonium salts such as phenylethylammonium salt, ethylenediammonium salt, and malonic acid diammonium salt are widely used. These ammonium salts have inherent photothermal instability and are prone to deprotonation and desorption under photothermal aging, resulting in passivation failure. The technical approach provided by this invention is to introduce a permanent positive charge at the terminal group to suppress or avoid the deprotonation process. The first characteristic of the passivation molecule of this invention is that the terminal group modification is achieved by introducing alkyl chain groups and aromatic groups to form a positive charge. At the same time, the passivation molecule material with terminal group modification has enhanced interfacial bonding ability and reduces the possibility of interfacial desorption.

[0020] (2) The second feature of the passivated molecule of the present invention is that the skeletal carbon chain in the middle of the molecule can be controlled by carbon chain engineering or conformational engineering to reduce the quantum confinement and strengthen the interlayer electronic coupling in the formation of low-dimensional perovskite phase.

[0021] (3) The third feature of the passivated molecule of the present invention is that the terminal cation can be replaced by elements, and the molecular dipole can be amplified by using atoms or groups with larger size or more polarizable electron clouds.

[0022] (4) The fourth feature of the passivating molecule of the present invention is that such passivating agent is a divalent cation that can form Dion-Jacobson (DJ) type two-dimensional perovskite.

[0023] The gain effect of the present invention:

[0024] (1) Compared with traditional passivating agents, the defect passivating agent provided by this invention has multiple functions: it can not only effectively passivate energy level defects at grain boundaries and interfaces and inhibit ion migration behavior, but also has excellent interfacial bonding ability due to its unique molecular structure, tending to form DJ-type two-dimensional perovskite phase in situ in the perovskite grain boundary region. The introduction of this two-dimensional component constructs a stable 2D / 3D bridging heterostructure, which not only significantly enhances the mechanical stability of grain boundaries, but also endows the film surface with certain hydrophobic properties, thereby synergistically improving the long-term stability of the interface under humid and hot environments.

[0025] (2) The terminal cation substitution strategy employed in this invention effectively suppresses the deprotonation tendency of the passivating agent. Compared with commonly used ammonium-based passivating agents (such as ethylenediammonium, propylenediammonium, phenylethylammonium, etc.) in the literature, this strategy significantly reduces the probability of deprotonation under high-temperature photothermal conditions by increasing the acid dissociation constant (pKa) of the cation. This characteristic is beneficial to maintaining the chemical structure and functional stability of the passivating agent in the perovskite film, thereby constructing an interface structure with excellent photothermal stability.

[0026] (3) The defect passivator proposed in this invention also has the function of energy level regulation. By optimizing the interface energy level matching and reducing the interface barrier, it can significantly enhance the extraction and transport efficiency of charge carriers at the perovskite / charge transport layer interface. This synergistic effect effectively suppresses the nonradiative recombination loss at the interface, thereby comprehensively improving the photovoltaic performance parameters of the battery and achieving a further breakthrough in photoelectric conversion efficiency. Attached Figure Description

[0027] Figure 1 The image shows the hydrogen nuclear magnetic resonance spectrum of the 4-bromine salt of the compound synthesized in Example 1.

[0028] Figure 2 This is a schematic diagram of the structure of the single-junction wide-bandgap perovskite solar cells in Examples 2, 4, 5 and Comparative Example 1.

[0029] Figure 3 This is a schematic diagram of the perovskite-crystalline silicon tandem solar cells in Examples 3, 4, 5 and Comparative Example 1.

[0030] Figure 4 The images are scanning electron microscope images of the wide-bandgap perovskite film surfaces in Example 2 and Comparative Example 1.

[0031] Figure 5 The fluorescence spectrum photoaging test results are shown in Example 2 and Comparative Example 1.

[0032] Figure 6 The images show the XRD test results of the perovskite films in Example 2 and Comparative Example 1 after aging at 100°C.

[0033] Figure 7 The current density-voltage (JV) test graphs of the single-junction perovskite solar cells in Example 2 and Comparative Example 1 are shown.

[0034] Figure 8 The current density-voltage (JV) test graphs are shown for the perovskite-crystalline silicon tandem solar cells in Example 3 and Comparative Example 1.

[0035] The labels in the diagram are: 1-glass; 2-indium tin oxide; 3-hole transport layer; 4-perovskite layer; 5-passivation layer; 6-electron transport layer; 7-hole blocking layer; 8-electrode; 9-electrode; 10-indium tin oxide; 11-a-Si:H(p); 12-a-Si:H(i); 13-c-Si; 14-a-Si:H(i); 15-a-Si:H(n); 16-indium tin oxide; 17-hole transport layer; 18-perovskite layer; 19-passivation layer; 20-electron transport layer; 21-tin dioxide; 22-indium zinc oxide; 23-electrode; 24-magnesium fluoride. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are merely preferred embodiments of the present invention and do not constitute a limitation on the scope of protection. All other embodiments obtained by those skilled in the art based on the content described in the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Example 1: Synthesis of the compound 4 series of compounds.

[0038] The reaction formula is:

[0039] ;

[0040] The specific steps of the synthesis are as follows:

[0041] Step 1: Synthesis of compound 4-bromine salt

[0042] At room temperature, bromoethylamine hydrobromide (1.024 g, 5 mmol, 1 eq) was added to a 100 mL two-necked flask and dissolved in 50 mL of ethanol. After stirring for 15 minutes, trimethylphosphine (0.3804 g, 5 mmol, 1 eq) was injected. The temperature was then raised to 60 °C and stirred for 36 hours. After the reaction was complete, most of the solvent was evaporated using a rotary evaporator, followed by washing three times with tetrahydrofuran and filtration. The final white powder product, compound 4-bromochloride (1.012 g, 3.60 mmol, yield 72%), was further obtained by vacuum drying. 1 H NMR (400 MHz, DMSO-d6) δ 8.23 ​​(s, 3H), 3.17 (q, J = 7.8 Hz, 2H), 2.68-2.55 (m, 2H), 1.98 (d, J = 15.2 Hz, 9H).

[0043] ;

[0044] Step 2: Synthesis of the derivative salt of compound 4

[0045] This invention also provides a method for synthesizing a series of derivative salts. Specifically, at room temperature, silver carbonate (Ag₂CO₃, 0.331 g, 1.2 mmol) is added to a beaker containing a solution of (2-aminoethyl)trimethylphosphine bromide (0.281 g, 1 mmol). The mixture is stirred vigorously overnight. Subsequently, the reaction mixture is filtered to obtain a clear filtrate. An aqueous solution of the corresponding HX acid, such as hydroiodic acid, hydrochloric acid, or tetrafluoroboric acid, is added to the filtrate with stirring, and a metathesis reaction is performed to obtain a solution of the derivative salt of compound 4. The remaining purification steps are consistent with the synthesis and purification of the bromide salt of compound 4.

[0046] Example 2: Fabrication and Testing of Device 1

[0047] Fabrication and Testing of Single-Junction Perovskite Solar Cells Based on Compound 4

[0048] The 4-bromine salt compound of this invention is used for passivation processing of perovskite solar cells. The device structure is: indium tin oxide (ITO) conductive glass / nickel oxide (NiO). x The device consists of a self-assembled monolayer (SAM), a perovskite layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode. The perovskite layer in this device is a 1.68 eV wide-bandgap perovskite Cs. 0.3 FA 0.6 DMA 0.1 Pb(I 0.87 Br 0.13 3. The passivation layer uses compound 4-bromine salt, the electron transport layer uses methyl (6,6)-phenyl-C61-butyrate (PCBM), the hole blocking layer uses copper bath (BCP), and the electrodes use high-purity silver (>99.99%). The device structure is as follows. Figure 2 As shown.

[0049] The specific steps for fabricating device 1 are as follows:

[0050] (1) Pretreatment: ITO glass with dimensions of 2 cm × 2 cm was selected as the transparent electrode. First, the etching stains on the film surface were cleaned with detergent. Then, the ITO glass was ultrasonically cleaned in the following order: diluted detergent solution, deionized water, ethanol, and isopropanol. The ultrasonic cleaning with diluted detergent and deionized water was 30 min, and the ultrasonic cleaning with ethanol and isopropanol was 15 min. After ultrasonic cleaning, the film was cleaned and dried with a nitrogen gun. Before using the ITO sheet, it was placed in an ozone cleaner for ozone cleaning treatment for 30 min.

[0051] (2) Hole transport layer preparation: A 10 mg mL⁻¹ NiOx nanoparticle aqueous dispersion was spin-coated onto an ITO substrate at 3000 rpm for 30 seconds, followed by annealing in air at 100 °C for 10 minutes. The resulting NiOx film was immediately transferred to a nitrogen glove box. A mixed self-assembled monolayer solution of Me-4PACz and MeO-2PACz (1 mM in ethanol, volume ratio 3:1) was spin-coated at 3000 rpm for 30 seconds, followed by annealing at 100 °C for 10 minutes.

[0052] (3) Perovskite layer preparation: 60 µL of perovskite precursor solution was dropped onto a glass / ITO / NiOx / SAM substrate. The spin-coating process consisted of two stages: the first stage was spin-coating at 2000 rpm for 15 seconds (acceleration 1000 rpm s⁻¹), and the second stage was spin-coating at 4000 rpm for 45 seconds (acceleration 2000 rpm s⁻¹). 30 seconds after the start of the second stage spin-coating process, nitrogen gas was blown vertically onto the substrate from a height of 5 cm above the substrate at a pressure of 0.3 MPa for 20 seconds. Subsequently, the wet film was aged at room temperature for 1 minute and annealed at 100 °C for 30 minutes. The nitrogen blowing time in this process can be, but is not limited to, 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, and 35 s. The aging time for the thin film at room temperature can be, but is not limited to, 20 s, 40 s, 60 s, 80 s, or 100 s.

[0053] (4) Passivation layer preparation: For the device of Example 1, the compound 4 bromine salt solution (preferably 1 mg mL⁻¹ in EtOH or FIPA) was spin-coated onto the perovskite surface at a speed of 5000 rpm for 30 seconds and then annealed at 100 °C for 5 minutes.

[0054] (5) Electron transport layer fabrication: PC 61 BM solution (23 mg mL⁻¹ in chlorobenzene) was spin-coated at 2500 rpm for 40 seconds and annealed at 70 °C for 10 minutes. Subsequently, BCP solution (0.5 mg mL⁻¹ in IPA) was spin-coated onto PC at 5000 rpm. 61 Spin-coat on BM film for 30 seconds.

[0055] (6) Electrode preparation: at 5×10 -4 A 100 nm thick Ag electrode was deposited by thermal evaporation at a vacuum of 0.1–1 t / s.

[0056] (7) Solar cell performance characterization: The device structure of the inverted perovskite solar cell prepared by the above method is as follows: Figure 5As shown, the effective area is 0.08 cm². 2 Test conditions: spectral distribution AM1.5G, light intensity 100 mW / cm² 2 The JV curve of the SS-X100R solar simulator was measured using a Keithly 2450 digital source meter. The test results are as follows: Figure 7 See Table 1.

[0057] Example 3: Fabrication and Testing of Device 2

[0058] Fabrication and Testing of Perovskite-Crystal Silicon Tandem Solar Cells Based on Compound 4

[0059] The 4-bromine salt compound of this invention is used for passivation processing of perovskite-crystalline silicon multijunction solar cells. The device structure is shown in Figure 3. The perovskite multijunction solar cells used in this invention are not limited to perovskite-crystalline silicon multijunction solar cells, but also include the application of the asymmetric dipole defect passivator provided by this invention in multijunction perovskite photovoltaics such as perovskite / perovskite tandem solar cells, perovskite / copper indium gallium selenide solar cells, perovskite / organic tandem solar cells, and perovskite / perovskite / silicon tandem solar cells.

[0060] The specific steps for fabricating device 2 are as follows:

[0061] (1) Hole transport layer preparation: On the surface of the commercially prepared silicon bottom cell, after ozonolysis treatment, Me-4PACz hole transport layer solution (0.5 mg / mL ethanol solution) was spin-coated at 4000 rpm for 30 s, and then annealed on a hot plate at 100 °C for 10 min.

[0062] (2) Perovskite layer preparation: 100 μL of a perovskite precursor solution (1.6 M) with a band gap of 1.68 eV was drop-coated onto the substrate and deposited using a two-step spin-coating method: in the first stage, the spin-coating was performed at an acceleration of 500 rpm / s to 2000 rpm for 10 s, and in the second stage, the spin-coating was performed at an acceleration of 5000 rpm / s to 5000 rpm for 30 s. 10 s before the end of the second stage spin-coating, 200 μL of anisole antisolvent was drop-coated onto the spinning substrate. After spin-coating, the film was immediately annealed on a hot plate at 100 °C for 15 min.

[0063] (3) Passivation layer preparation: Referring to the passivation process of single-junction perovskite solar cells, the salt solution of compound 4 (solvent is EtOH or FIPA, concentration optimized) was spin-coated on the perovskite surface at 5000 rpm for 30 s, and then annealed at 100 °C for 5 min.

[0064] (4) Electron transport layer preparation: 25 nm C60 was deposited by thermal evaporation at a deposition rate of 0.1 Å / s; then 21 nm SnO2 was grown by atomic layer deposition at 80°C.

[0065] (5) Subsequent processes and electrode preparation: 25 nm indium zinc oxide was sputtered by mask, followed by thermal evaporation to deposit 200 nm silver interdigital electrodes, and finally 130 nm magnesium fluoride antireflection layer was deposited by electron beam evaporation.

[0066] (6) Solar cell performance characterization: The device structure of the perovskite-crystalline silicon tandem solar cell prepared by the above method is as follows: Figure 3 As shown, the effective area is 1.05 cm². 2 At 25℃, using a light intensity of 100 mW / cm² 2 JV measurements were performed using a solar simulator (Wavelabs, LED), with a Keithley 2450 source meter. The test results are as follows: Figure 8 And Table 2.

[0067] Comparative Example 1

[0068] For comparison, ethylenediamine hydroiodide (EDAI), a defect passivating agent already reported in the literature, was used, where the chemical formula of ethylenediamine is as shown in formula (II).

[0069]

[0070] (II)

[0071] Comparative Device 3: Fabrication and Testing of a Single-Junction Perovskite Solar Cell Based on EDAI

[0072] The fabrication and testing of the single-junction wide-bandgap perovskite solar cell based on the comparative passivator EDAI were the same as in Example 1, except that the passivation layer material was replaced with the comparative compound EDAI, and the device structure was the same. Figure 2 The test results are shown in Table 1.

[0073] Comparative Device 4: Fabrication and Testing of EDAI-based Perovskite-Crystalline Solar Cells

[0074] The fabrication and testing of perovskite-crystalline silicon tandem solar cells based on the comparative passivator EDAI were the same as in Example 2, except that the passivation layer material was replaced with the comparative compound EDAI, and the device structure was the same. Figure 3 The test results are shown in Table 2.

[0075] Example 4: Fabrication and testing of perovskite solar cells based on compound 1 passivation

[0076] Device 5, a single-junction wide-bandgap perovskite solar cell based on compound 1 bromide passivation, was fabricated and tested in the same manner as in Example 1, except that the passivation layer material was replaced with compound 1 bromide. The device structure was the same. Figure 2 The test results are shown in Table 1.

[0077] Device 6, based on the perovskite-crystalline silicon tandem solar cell passivated with compound 1 bromide, was fabricated and tested in the same manner as in Example 2, except that the passivation layer material was replaced with compound 1 bromide, and the device structure was the same. Figure 3 The test results are shown in Table 2.

[0078] Example 5: Fabrication and Testing of Perovskite Solar Cells Passivated by Compound 22

[0079] Device 7, a single-junction wide-bandgap perovskite solar cell based on compound 22 hydrochloride passivation, was fabricated and tested in the same manner as in Example 1, except that the passivation layer material was replaced with compound 22 hydrochloride. The device structure was the same. Figure 2 The test results are shown in Table 1.

[0080] Device 8, based on the perovskite-crystalline silicon tandem solar cell passivated with compound 22 hydrochloride, was fabricated and tested in the same manner as in Example 2, except that the passivation layer material was replaced with compound 22 hydrochloride, and the device structure was the same. Figure 3 The test results are shown in Table 2.

[0081] Table 1 Summary of performance parameters of single-junction wide-bandgap perovskite solar cells

[0082] .

[0083] Table 2 Summary of performance parameters of perovskite-crystalline silicon tandem solar cells

[0084] .

[0085] Surface and stability testing of perovskite thin films

[0086] Following the fabrication steps (1)-(4) of devices 1 and 3 described above, perovskite thin film samples were prepared. First, the surface of the perovskite thin film was tested using a scanning electron microscope (SEM), and the results are as follows: Figure 4 As shown.

[0087] To further investigate the effect of the passivation layer on the stability of perovskite, perovskite films were prepared following the same steps described above. Fluorescence emission spectroscopy (FE-ES) aging tests and X-ray diffraction (XRD) aging tests were then performed. The passivation layer used compounds 4-bromine salt and EDAI, respectively. Fluorescence aging was conducted using an equivalent solar LED light source. The XRD aging temperature was 100 °C, and the aging time was 100 hours. The results are as follows: Figure 5 and Figure 6 .

[0088] Results Analysis

[0089] The following analysis of the test data and charts in Example 1 and Comparative Example 1 illustrates in detail the advantages of using the defect passivator provided by the present invention in solar cells.

[0090] Depend on Figure 7 As shown in Table 1, compared to EDAI, the performance parameters of the solar cells treated with the defect passivator compound 4 provided by this invention are significantly improved, exhibiting higher open-circuit voltage, short-circuit current, and fill factor. Furthermore, the defect passivator provided by this invention, when applied to perovskite-crystalline silicon multijunction solar cells, significantly improves the device's open-circuit voltage and fill factor, and the improved photoelectric conversion efficiency demonstrates the gain effect mentioned in this application.

[0091] Depend on Figure 4 and Figure 6 It is known that both defect passivators passivate the surface morphology of perovskite. The treatment with EDAI passivator eliminates the presence of lead iodide impurity phase, while compound 4 provided by the present invention not only eliminates lead iodide impurity phase, but also generates a low-dimensional new phase at the grain boundary. This new phase is a low-dimensional perovskite phase formed by the reaction with lead iodide, which is beneficial to stabilizing the grain boundary.

[0092] Depend on Figure 5 It can be seen that after aging for 1 hour at 25°C and 3 equivalent solar energy, the perovskite / passivated interface constructed by the defect passivator compound 4 provided by the present invention has excellent photostability and no fluorescence spectrum shift caused by halogen phase separation occurs. In contrast, the fluorescence spectrum of the EDAI passivator shifted significantly after 1 hour of aging, proving that the interface passivation failure occurred.

[0093] Depend on Figure 6 It can be seen that after aging at 100°C for 100 hours, the perovskite / passivated interface constructed by the defect passivator compound 4 provided by the present invention has excellent thermal stability. It not only eliminates the lead iodide phase at around 12.6°, but also does not degrade at the interface under high temperature aging, which proves the excellent thermal stability of the interface. However, after 31 hours of aging, the lead iodide peak reappeared in the XRD pattern of the EDAI passivator, and its intensity increased with the increase of high temperature aging time, which proves the occurrence of interface passivation failure and interface degradation.

[0094] In summary, the above test analysis shows that the asymmetric dipole structure molecular passivation material provided by this invention, when used as an interface passivation material, has stronger interfacial bonding ability and excellent photothermal stability. It can effectively achieve defect passivation, energy level optimization, enhanced interfacial charge transport, and interface stabilization of perovskite thin films, thereby significantly improving the efficiency and stability of perovskite solar cells.

[0095] Furthermore, by utilizing the molecular passivation material with asymmetric dipole structure of general formula (I) provided by this invention, combined with existing technical means in the field, those skilled in the art can also use the compound with general formula (I) claimed in this invention for other perovskite multijunction solar cells, including perovskite / perovskite tandem solar cells, perovskite / copper indium gallium selenide solar cells, perovskite / organic tandem solar cells, and perovskite / perovskite / silicon tandem solar cells.

Claims

1. A defect passivation material based on an asymmetric dipole structure, characterized in that, It has an asymmetric dipole structure, and its general chemical formula is: ； （Ⅰ） In the formula, the two terminal cationic groups are an ammonium cationic group and an alkylated A cationic group, connected by a carbon chain or aromatic ring; n is an integer from 1 to 20, and B is a neutralizing anionic group; where: Cation A is selected from the elements nitrogen, phosphorus, sulfur, selenium, and oxygen; The group represented by X is independently selected from: hydrogen atom (H), methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), butyl (-CH2CH2CH2CH3) alkyl, phenyl, benzyl, naphthyl, anthracene, phenanthrene, pyrene, thiophene, selenophenol, furanyl, pyrrolyl, pyridyl, indolyl, imidazolyl, thiazolyl, pyrimidinyl, cycloheptyl, cyclohexyl, cyclopentyl, cyclobutyl, cyclopropyl, cyclopentenyl, cyclopentadienyl; The anionic group represented by B is independently selected from: fluoride ion (F... - ), chloride ions (Cl) - ), bromide ions (Br) - ), iodide ions (I - ), thiocyanate (SCN) - ), cyanate (OCN) - ), cyanide (CN) - ), hexafluorophosphate ([PF6]) - ), tetrafluoroborate ([BF4]) - ), perrhenate ([ReO4]) - ), nitrate ([NO3]) - ), formate (HCOO) - Acetate (CH3COO) - ), trifluoroacetate (CF3COO) - ), Methylsulfonate (CH3SO3) - ), trifluoromethanesulfonate (CF3SO3) - ), bis(trifluoromethanesulfonyl)([N(SO2CF3)2) - ).

2. The defect passivation material based on an asymmetric dipole structure according to claim 1, characterized in that, It is any one of the following compounds 1-35: 。 3. The application of the defect passivation material based on the asymmetric dipole structure as described in claim 1 or 2 as a defect passivation in solar cells, wherein the solar cells include perovskite solar cells and multijunction tandem solar cells.

4. The application according to claim 3, characterized in that, The defect passivation material is used to form a passivation layer on the perovskite buried interface (perovskite / hole transport layer) and the perovskite upper interface (perovskite / electron transport layer) of the perovskite solar cell by spin coating, inkjet printing, vacuum evaporation, dip coating or molecular beam evaporation, with a passivation layer thickness of 1 to 20 nm.

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