Perovskite solar cell and method of manufacturing the same

Abstract

The present application relates to a kind of perovskite solar cell and preparation method thereof, wherein, perovskite solar cell, including perovskite light absorption layer, the perovskite light absorption layer includes the aqueous polyurethane with acylhydrazone bond.In the present application, perovskite solar cell utilizes the aqueous polyurethane with acylhydrazone bond, so that it can realize self-repair under the condition of 50 ℃-60 ℃, so that it has excellent photoelectric conversion efficiency and stability.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to perovskite solar cells and their fabrication methods. Background Technology

[0002] In recent years, perovskite materials have become one of the most promising optoelectronic materials in the field of optoelectronic devices due to their excellent photoelectric properties. While perovskite solar cells currently exhibit good photoelectric conversion efficiency, numerous defects exist between grain boundaries during the formation of perovskite materials. Furthermore, the ionic nature of perovskite materials makes them sensitive to radiation and humidity, and they are easily degraded when exposed to atmospheric conditions, leading to a loss of performance and stability, severely impacting their usability. In addition, due to the inherent brittleness of perovskite materials, stress-induced cracks can propagate along grain boundaries during repeated bending or stretching, thus affecting the photoelectric conversion efficiency of perovskite solar cells.

[0003] To improve the self-healing ability, photoelectric conversion efficiency, and stability of perovskite solar cells, traditional technologies typically utilize self-healing polymers, such as polyurethane elastomers with disulfide bonds, to construct repairable perovskite solar cells and enhance the self-healing perovskite film through phase-locked loops. However, this polyurethane elastomer achieves self-healing through thermal drive, with a self-healing temperature of 80°C. In contrast, perovskite solar cells, under normal use and continuous illumination, are generally maintained at 50°C-60°C, not 80°C. This results in poor self-healing capabilities, leading to lower photoelectric conversion efficiency and stability. Summary of the Invention

[0004] Therefore, it is necessary to provide a perovskite solar cell and its preparation method to address the above problems. This perovskite solar cell utilizes aqueous polyurethane with acylhydrazone bonds, which can achieve self-repair at 50℃-60℃, thereby enabling the perovskite solar cell to have excellent photoelectric conversion efficiency and stability.

[0005] A perovskite solar cell includes a perovskite light-absorbing layer comprising an aqueous polyurethane having acylhydrazone bonds.

[0006] In one embodiment, the aqueous polyurethane having acylhydrazone bonds has the following structural formula (1).

[0007]

[0008] In equation (1), -R2- is selected from any of the following equations: (2) - (5).

[0009]

[0010]

[0011] In equations (2) to (5), -R1- is selected from the following equation (6). Where n is selected from 5-25.

[0012] In one embodiment, the aqueous polyurethane with acylhydrazone bonds has a mass fraction of 0.1%-1% in the perovskite light-absorbing layer;

[0013] And / or, the relative molecular mass of the aqueous polyurethane having acylhydrazone bonds is 10,000-30,000.

[0014] In one embodiment, the perovskite material in the perovskite light-absorbing layer has the general structural formula ABX3, where A is selected from CH3NH3. + CH(NH2)2 + and Cs + At least one of them, B is selected from Pb 2+ Sn 2+ At least one of them, X is selected from Br - I - Cl - At least one of them.

[0015] In one embodiment, the solar cell further includes a transparent conductive substrate layer, a hole transport layer, an electron transport layer, and a conductive electrode layer, wherein the transparent conductive substrate layer, the hole transport layer, the perovskite light absorption layer, the electron transport layer, and the conductive electrode layer are stacked sequentially to form an inverted perovskite solar cell.

[0016] In one embodiment, a passivation layer is further included, which is disposed between the electron transport layer and the conductive electrode layer.

[0017] In one embodiment, the thickness of the transparent conductive substrate layer is 100nm-1000nm, the thickness of the hole transport layer is 5nm-50nm, the thickness of the perovskite light-absorbing layer is 300nm-1000nm, the thickness of the electron transport layer is 20nm-200nm, the thickness of the passivation layer is 5nm-20nm, and the thickness of the conductive electrode layer is 50nm-1000nm.

[0018] A method for fabricating a perovskite solar cell as described above includes the following steps:

[0019] A hole transport layer is fabricated on a transparent conductive substrate;

[0020] An aqueous polyurethane solution with acylhydrazone bonds is added to a perovskite precursor solution and mixed to obtain a doped perovskite precursor solution. The doped perovskite precursor solution is then placed on the surface of the hole transport layer and annealed to obtain a perovskite light absorption layer.

[0021] An electron transport layer is fabricated on the perovskite light-absorbing layer;

[0022] A conductive electrode layer is fabricated on the electron transport layer to obtain a perovskite solar cell.

[0023] In one embodiment, the aqueous polyurethane having acylhydrazone bonds has a mass concentration of 0.01 mg / mL to 50 mg / mL in the doped perovskite precursor solution.

[0024] In one embodiment, before fabricating a conductive electrode layer on the electron transport layer, the step further includes: fabricating a passivation layer on the electron transport layer.

[0025] In the perovskite solar cell of the present invention, by adding an aqueous polyurethane having acylhydrazone bonds to the perovskite light-absorbing layer, on the one hand, the acylhydrazone bonds can enhance the absorption of metal cations and / or halide ions (such as Pb) in the perovskite light-absorbing layer. 2+ I - The reversible reaction, induced by the lone pair electrons provided by the polyurethane, restores the broken bonds, enabling the self-healing of the waterborne polyurethane. This allows the perovskite light-absorbing layer to self-heal at 50℃-60℃, thereby repairing surface defects in the perovskite. On the other hand, the waterborne polyurethane structure with acylhydrazone bonds contains a large number of special functional groups (such as hydroxyl, carbonyl, and carboxyl groups). These special functional groups enable the waterborne polyurethane with acylhydrazone bonds to combine with uncoordinated anionic and cation defects in the perovskite absorber layer to form a dense, waterproof, and heat-insulating self-healing polymer film. This greatly improves the temperature and humidity stability of the perovskite light-absorbing layer, thereby significantly enhancing the stability of the perovskite solar cell.

[0026] Therefore, through the synergistic effect of self-healing acylhydrazone bonds and special functional groups, perovskite solar cells can achieve self-repair at 50℃-60℃, which not only makes their crystal phase more stable, effectively promotes carrier transport, and improves the photoelectric conversion efficiency of perovskite solar cells, but also effectively prevents water intrusion and heat intrusion, thus improving the performance stability of perovskite solar cells. Attached Figure Description

[0027] Figure 1 This is a flowchart of the entire preparation reaction of the aqueous polyurethane with acylhydrazone bonds in Example 1 of the present invention;

[0028] Figure 2The images show the XRD patterns of the perovskite films prepared in Example 1 and Comparative Example 1 of this invention, where A represents Example 1 and B represents Comparative Example 1.

[0029] Figure 3 The images show the photoluminescence spectra of the perovskite thin films prepared in Example 1 and Comparative Example 1 of the present invention, where C represents Example 1 and D represents Comparative Example 1.

[0030] Figure 4 The graphs show the current-voltage curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1 of this invention, where F represents Example 1 and E represents Comparative Example 1.

[0031] Figure 5 The graph shows the change in photoelectric conversion efficiency of the perovskite solar cells prepared in Example 1 and Comparative Example 1 of the present invention at different time points when stored in an 85% humidity environment.

[0032] Figure 6 The graph shows the change in photoelectric conversion efficiency of the perovskite solar cells prepared in Example 1 and Comparative Example 2 of this invention under different bending cycles. Detailed Implementation

[0033] The perovskite solar cell and its preparation method provided by the present invention will be further described below.

[0034] The present invention provides a perovskite solar cell, comprising a perovskite light-absorbing layer, wherein the perovskite light-absorbing layer comprises an aqueous polyurethane having acylhydrazone bonds.

[0035] Acylhydrazone bonds are dynamic covalent bonds that can recover from breakage under heating temperatures of 50℃-60℃ and acid stimulation, enabling self-healing in polymer materials. Meanwhile, waterborne polyurethane (WPU) possesses excellent mechanical properties, superior flexibility, optical properties, ease of preparation, and low manufacturing cost. Furthermore, acylhydrazone bonds can restore the structure of perovskite structures containing metal cations and / or halide ions (e.g., Pb). 2+ I - The lone pair electrons provided by the polyurethane can be used to excite the polyurethane and replace acid stimulation to carry out a reversible reaction, thereby restoring the broken bonds and achieving self-healing of waterborne polyurethane.

[0036] Therefore, this invention incorporates an aqueous polyurethane with acylhydrazone bonds into the perovskite light-absorbing layer. The acylhydrazone bonds in the aqueous polyurethane structure can interact with metal cations and / or halide ions (such as Pb) in the perovskite light-absorbing layer. 2+ I - The lone pair electrons provided by the polyurethane provide a reversible reaction instead of acid stimulation, enabling the waterborne polyurethane to heal itself. This allows the perovskite light absorption layer to self-heal at 50℃-60℃, thereby repairing surface defects in the perovskite.

[0037] Meanwhile, because the aqueous polyurethane structure with acylhydrazone bonds contains a large number of special functional groups (such as hydroxyl, carbonyl and carboxyl groups), these special functional groups can enable the aqueous polyurethane with acylhydrazone bonds to combine with uncoordinated anions and cation defects in the perovskite absorber layer to form a dense, waterproof and heat-insulating self-healing polymer film. This greatly improves the temperature and humidity stability of the perovskite light absorber layer, thereby significantly enhancing the stability of the perovskite solar cell.

[0038] Thus, through the synergistic effect of self-healing acylhydrazone bonds and special functional groups, perovskite solar cells can achieve self-repair at 50℃-60℃, which not only makes their crystal phase more stable, effectively promotes carrier transport, and improves the photoelectric conversion efficiency of perovskite solar cells, but also effectively prevents water intrusion and heat intrusion, thereby improving the performance stability of perovskite solar cells.

[0039] As can be seen, compared with perovskite solar cells constructed using polyurethane elastomers with disulfide bonds, the perovskite solar cells of the present invention can achieve self-repair under conditions of 50℃-60℃, thus exhibiting excellent photoelectric conversion efficiency and stability.

[0040] In addition, traditional polyurethanes, such as thermoplastic polyurethane (TPU), have extremely high viscosity and degree of polymerization after preparation, making them difficult to swell in N,N-dimethylformamide (DMF). As a result, when added to the perovskite precursor solution, it affects the formation of the perovskite film, and the resulting polyurethane film is relatively thick, which greatly affects the transport of photogenerated carriers in the perovskite and thus affects the photoelectric performance of the perovskite solar cell.

[0041] The aqueous polyurethane with acylhydrazone bonds in this invention, being dispersed in water, can achieve a low particle size, allowing for the removal of water by rotary evaporation and subsequent swelling in DMF solvent. This facilitates its introduction into the perovskite precursor solution, promoting the formation of the perovskite light-absorbing layer. Furthermore, the self-healing polymer film formed on the surface of the perovskite light-absorbing layer by the aqueous polyurethane with acylhydrazone bonds is relatively thin, thus not affecting the transport of photogenerated carriers in the perovskite, thereby improving the photoelectric performance of the perovskite solar cell.

[0042] In one embodiment, the aqueous polyurethane having acylhydrazone bonds has the following structural formula (1).

[0043]

[0044] In equation (1), -R2- is selected from any of the following equations: (2) - (5).

[0045]

[0046]

[0047] In equations (2) to (5), -R1- is selected from the following equation (6). Wherein, n is selected from 5 to 25, and preferably, n is 10.

[0048] This configuration results in a very small particle size for the aqueous polyurethane with acylhydrazone bonds, allowing for better swelling in DMF solvent and facilitating its introduction into the perovskite precursor solution, thus promoting the formation of the perovskite light-absorbing layer. Simultaneously, the acylhydrazone bonds in this aqueous polyurethane structure can better accommodate metal cations and / or halide ions (e.g., Pb) in the perovskite light-absorbing layer. 2+ I - The self-healing properties of perovskite solar cells are improved by using lone pair electrons provided by the polyurethane to replace acid stimulation, thereby enhancing the photoelectric performance of perovskite solar cells at 50℃-60℃. Simultaneously, the aqueous polyurethane structure with acylhydrazone bonds possesses sufficient special functional groups (such as polar carbonyl groups), enabling it to better combine with uncoordinated anionic and cation defects to form a dense, waterproof, and heat-insulating self-healing polymer film, thus improving the performance stability of perovskite solar cells.

[0049] In order to better disperse the aqueous polyurethane with acylhydrazone bonds in the perovskite precursor solution, enabling the perovskite solar cell to achieve self-repair at 50℃-60℃ and thus exhibiting excellent photoelectric conversion efficiency and performance stability, the present invention preferably specifies that the mass fraction of the aqueous polyurethane with acylhydrazone bonds in the perovskite light-absorbing layer is 0.1%-1%.

[0050] In one embodiment, the relative molecular mass of the aqueous polyurethane with acylhydrazone bonds is 10,000-30,000. This configuration results in a lower viscosity and a lower degree of polymerization for the aqueous polyurethane with acylhydrazone bonds, facilitating its swelling in DMF solvent and its smooth introduction into the perovskite precursor solution, thus improving the formation effect of the perovskite light-absorbing layer.

[0051] Perovskite is a crystalline material with the general molecular formula ABX3, exhibiting an octahedral shape and excellent structural properties. In the octahedral structure of perovskite, A is the larger cation, B is the smaller cation, and X is the anion. Each A ion is surrounded by an octahedron formed by B and X ions. Typically, in the ABX3 structure of perovskite, A is an organic cation and / or a metal cation, such as the organic cation methylamine CH3NH3. + (MA +), formamidinium NH2CH=NH2 + (FA + ), metal cation cesium Cs + , Rubidium Rb + etc.; B is generally a divalent metal cation, such as lead ion Pb. 2+ Tin ions (Sn) 2+ X is generally a halide anion, often a chloride ion (Cl). - Bromide ions (Br) - Iodide ions - wait.

[0052] Preferably, in this invention, the perovskite material in the perovskite light-absorbing layer has the general structural formula ABX3, wherein A is selected from CH3NH3. + CH(NH2)2 + and Cs + At least one of them, B is selected from Pb 2+ Sn 2+ At least one of them, X is selected from Br - I - Cl - At least one of the following. More preferably, the perovskite material in the perovskite light-absorbing layer is selected from at least one of CH3NH3PbI3 and CH(NH2)2PbI3. This configuration can provide a higher electron cloud density within the aqueous polyurethane molecules with acylhydrazone bonds, further promoting the breaking and recombination of acylhydrazone bonds, realizing the dynamic healing of acylhydrazone bonds, thereby achieving self-repair of the perovskite light-absorbing layer, and thus realizing the self-repair capability of the perovskite solar cell.

[0053] In one embodiment, the perovskite solar cell of the present invention further includes a transparent conductive substrate layer, a hole transport layer, an electron transport layer, and a conductive electrode layer. By adjusting the arrangement order of the transparent conductive substrate layer, the hole transport layer, the perovskite light-absorbing layer, the electron transport layer, and the conductive electrode layer, an inverted or conventional perovskite solar cell can be formed. Preferably, an inverted perovskite solar cell is used, i.e., the transparent conductive substrate layer, the hole transport layer, the perovskite light-absorbing layer, the electron transport layer, and the conductive electrode layer are stacked sequentially from bottom to top.

[0054] Furthermore, it also includes a passivation layer disposed between the electron transport layer and the conductive electrode layer.

[0055] In one embodiment, the sheet resistance of the transparent conductive substrate layer is 5Ω-25Ω and the transmittance is 70%-95%. Preferably, the material of the transparent conductive substrate is selected from FTO (fluorine-doped tin oxide) conductive glass or ITO (indium tin oxide) conductive glass.

[0056] In one embodiment, the hole transport layer is made of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz). Compared with the commonly used poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), MeO-2PACz can effectively improve the nucleation and growth of spin-coated perovskite films, form a dense and uniform interface, and promote the interaction with the perovskite light-absorbing layer to passivate interface defects, which is beneficial to improving the efficiency and stability of perovskite solar cells.

[0057] In one embodiment, the material of the electron transport layer is selected from methyl [6,6]-phenyl-C61-butyrate (PC). 61 At least one of BM, TiO2, SnO2, and ZnO, preferably, the material of the electron transport layer is selected from PC. 61 The BM configuration enables rapid and efficient charge transfer and exciton dissociation, and features high electron mobility, allowing electrons to be transported from the perovskite light-absorbing layer to the transparent conductive substrate, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0058] In one embodiment, the material of the passivation layer is selected from (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) (BCP). On the one hand, BCP can improve the transport of the electron transport layer fluid, and on the other hand, it can form a protective layer on the surface of the electron transport layer to improve the stability of the device.

[0059] In one embodiment, the material of the conductive electrode layer is selected from at least one of metals and metal oxides, wherein the metal can be Au or Ag, and the metal oxide can be molybdenum trioxide.

[0060] Considering the miniaturization and structural strength of perovskite solar cells, the present invention preferably includes the following: the thickness of the transparent conductive substrate layer is 100nm-1000nm, the thickness of the hole transport layer is 5nm-50nm, the thickness of the perovskite light absorption layer is 300nm-1000nm, the thickness of the electron transport layer is 20nm-200nm, the thickness of the passivation layer is 5nm-20nm, and the thickness of the conductive electrode layer is 50nm-1000nm.

[0061] Meanwhile, the present invention also provides a method for preparing a perovskite solar cell, comprising the following steps:

[0062] S1. Prepare a hole transport layer on a transparent conductive substrate;

[0063] S2. An aqueous polyurethane solution with acylhydrazone bonds is added to a perovskite precursor solution and mixed to obtain a doped perovskite precursor solution. The doped perovskite precursor solution is then placed on the surface of the hole transport layer and annealed to obtain a perovskite light absorption layer.

[0064] S3. An electron transport layer is prepared on the perovskite light-absorbing layer;

[0065] S4. A conductive electrode layer is prepared on the electron transport layer to obtain a perovskite solar cell.

[0066] Specifically, in step S1, FTO conductive glass or ITO conductive glass with a sheet resistance of 5Ω-25Ω, a transmittance of 70%-95%, and a size of 1.9cm×1.9cm is selected as the transparent conductive substrate. Before use, the transparent conductive substrate is pretreated. The pretreatment process is as follows: the transparent conductive substrate is ultrasonically treated with deionized water, acetone, and isopropanol in sequence, dried with nitrogen, and then cleaned by ultraviolet light irradiation for 30 minutes.

[0067] A hole transport layer precursor solution is spin-coated onto a transparent conductive substrate, followed by annealing to obtain a hole transport layer with a thickness of 5 nm-50 nm. The spin-coating speed is 2500 rpm-3500 rpm, the spin-coating time is 25 s-35 s, the annealing temperature is 80℃-120℃, the annealing time is 8 min-12 min, and the mass concentration of the hole transport layer precursor solution is 0.1 mg / mL-0.5 mg / mL. This configuration facilitates the formation of a smooth and dense electron transport layer. Preferably, the hole transport layer precursor solution is an ethanol solution of MeO-2PACz.

[0068] In step S2, the method for preparing the aqueous polyurethane solution with acylhydrazone bonds includes the following steps:

[0069] S21. The first monomer, the second monomer, the first chain extender and the catalyst are added to a flask and reacted at 75℃-95℃ for 2h-3h under a protective gas atmosphere. Then the mixture is cooled to 50℃-70℃ to obtain an intermediate. The molar ratio of the first monomer and the second monomer is 1:1.1-1:1.3.

[0070] S22. Add the second chain extender to the intermediate obtained in step S21, continue the reaction for 1-2 hours, and then adjust the temperature to 30℃-50℃ to obtain the prepolymer. The second chain extender includes 1,4-butanediol (BDO) and reversible covalent acylhydrazonediol (PA).

[0071] S23. Add a neutralizing agent to the prepolymer obtained in step S22, continue the reaction for 20 min-40 min, then add 40 mL-60 mL of deionized water and stir to mix, to obtain an aqueous polyurethane with acylhydrazone bonds, wherein the stirring speed is 800 r / min-1200 r / min and the stirring time is 8 min-12 min, and the neutralizing agent is selected from at least one of triethanolamine (TEA) and dimethylethanolamine (DMEA);

[0072] S24. Add an organic solvent to the aqueous polyurethane with acylhydrazone bonds obtained in step S23, and then remove the water by rotary evaporation to obtain an aqueous polyurethane solution with acylhydrazone bonds, wherein the organic solvent is DMF.

[0073] In one embodiment, in step S21, the first monomer is selected from any one of the compounds shown in formulas (7) to (10). Preferably, the first monomer is selected from the compounds shown in formula (7).

[0074] In step S21, the second monomer is selected from the compound shown in formula (11). Where n is selected from 5-25.

[0075] For example, when n is 10, the second monomer is selected from the compound shown in formula (12).

[0076] When n is 20, the second monomer is selected from the compound shown in formula (13).

[0077] When n is 6, the second monomer is selected from the compound shown in formula (14).

[0078] This configuration allows the aqueous polyurethane with acylhydrazone bonds to have sufficient special functional groups and reversible acylhydrazone bonds, enabling it to be doped into the perovskite light absorption layer as an additive. This allows the perovskite solar cell to self-repair at 50℃-60℃, resulting in excellent photoelectric conversion efficiency and stability.

[0079] In one embodiment, in step S21, the first chain extender is a hydrophilic chain extender, and the first chain extender is selected from at least one of dimethylolpropionic acid (DMPA) and dimethylolbutyric acid (DMBA).

[0080] In one embodiment, in step S21, the catalyst is selected from at least one of dibutyltin dilaurate (DBTDL) and stannous octoate.

[0081] In one embodiment, the intermediate is prepared in step S21 as follows: the first monomer, the second monomer, and the catalyst are first added to a flask and reacted at 75°C-95°C for 2-3 hours under a protective gas atmosphere to obtain the reaction monomer. Then, the first chain extender is added and the reaction continues for 1-2 hours to obtain the intermediate.

[0082] For example, when the first monomer is the compound shown in formula (7), the second monomer is the compound shown in formula (12), the catalyst is dibutyltin dilaurate (DBTDL), and the first chain extender is dimethylolpropionic acid (DMPA), the reactant monomer is the compound shown in formula (15) below. The intermediate is a compound as shown in formula (16). Wherein, -R1- is as shown in equation (17) below.

[0083] In one embodiment, in step S2, the perovskite precursor solution is obtained by dissolving the perovskite material in an organic solvent, wherein the perovskite material in the perovskite light-absorbing layer has the general structural formula ABX3, where A is selected from CH3NH3. + CH(NH2)2 + and Cs + At least one of them, B is selected from Pb 2+ Sn 2+ At least one of them, X is selected from Br - I - Cl - At least one of the following, preferably, the perovskite material in the perovskite light-absorbing layer is selected from at least one of CH3NH3PbI3 and CH(NH2)2PbI3, and the organic solvent is a mixed solvent composed of methylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0084] In one embodiment, in step S2, the mass concentration of the aqueous polyurethane with acylhydrazone bonds in the doped perovskite precursor solution is 0.01 mg / mL-50 mg / mL, preferably 2 mg / mL-15 mg / mL. This setting ensures that the aqueous polyurethane with acylhydrazone bonds can combine with uncoordinated anions and cations in the perovskite absorber layer to form a dense, waterproof, and heat-insulating self-healing polymer film, while not affecting the spreadability of the perovskite precursor solution on the hole transport layer surface, nor inhibiting the spread of the electron transport layer precursor solution on the perovskite layer surface. This ensures that the addition of the aqueous polyurethane with acylhydrazone bonds does not adversely affect the electron transport layer and hole transport layer, ensuring that the prepared perovskite solar cell has a self-healing effect under low-temperature conditions, while also exhibiting excellent photoelectric conversion efficiency and stability.

[0085] In step S2, the doped perovskite precursor solution is spin-coated onto the surface of the hole transport layer, and diethyl ether is dropped in during the spin-coating process. Then, annealing is performed to obtain a perovskite light absorption layer with a thickness of 300nm-1000nm. The spin-coating speed is 3500rpm-4500rpm, the spin-coating time is 20s-30s, the annealing temperature is 80℃-120℃, the annealing time is 50min-70min, and diethyl ether is dropped in during the remaining 8s-12s of the spin-coating time.

[0086] In step S3, the electron transport layer precursor solution is spin-coated onto the perovskite light-absorbing layer, followed by annealing to obtain an electron transport layer with a thickness of 20 nm-200 nm. The spin-coating speed is 1500 rpm-2500 rpm, the spin-coating time is 25 s-35 s, the annealing temperature is 60℃-80℃, the annealing time is 50 s-70 s, and the mass concentration of the electron transport layer precursor solution is 15 mg / mL-25 mg / mL. Preferably, the electron transport layer precursor solution is PC. 61 BM's chlorobenzene solution.

[0087] In step S4, a conductive electrode layer with a thickness of 50nm-1000nm is deposited on the electron transport layer obtained in step S3 using a vacuum evaporation coating device to obtain an inverted perovskite solar cell. The conductive electrode layer is selected from Au, Ag, or molybdenum trioxide layers, and the vacuum degree of the vacuum evaporation is 10. -4 Pa-10 -3 Pa, the evaporation rate is 0.1A / s-1A / s.

[0088] In one embodiment, before step S4, the method further includes the following steps: spin-coating a passivation layer precursor solution onto an electron transport layer, followed by annealing to obtain a passivation layer with a thickness of 5 nm-20 nm. The spin-coating speed is 3500 rpm-4500 rpm, the spin-coating time is 25 s-35 s, the annealing temperature is 90 °C-110 °C, the annealing time is 50 s-70 s, and the mass concentration of the passivation layer precursor solution is 0.2 mg / mL-0.8 mg / mL. Preferably, the electron transport layer precursor solution is an isopropanol (IPA) solution of BCP.

[0089] The perovskite solar cells prepared by this method can self-repair under conditions of 50℃-60℃, giving them excellent photoelectric conversion efficiency and stability.

[0090] The perovskite solar cell and its fabrication method will be further described below through specific embodiments.

[0091] It should be noted that the raw materials and reagents used in the embodiments and comparative examples of this invention are all commercially available. Furthermore, this invention uses a PLmapping instrument (PMEye-3000, China) to detect the perovskite films prepared in Example 1 and Comparative Example 1, obtaining the corresponding photoluminescence spectra, wherein the samples are excited by a 450 nm laser. In addition, this invention uses an X-ray diffractometer (XRD) (ADVANCE D8, Germany) to test the perovskite films prepared in Example 1 and Comparative Example 1, wherein the scanning range is 5°-60° and the scanning rate is 6° / min, obtaining the corresponding X-ray diffraction (XRD) spectra.

[0092] Example 1

[0093] 10.97 g of the first monomer, 6 g of the second monomer, 1.187 g of the first chain extender and the catalyst were added to a four-necked flask equipped with a nitrogen inlet, a condenser and a stirrer. The mixture was reacted at 85 °C for 2-3 hours under a N2 atmosphere to obtain an intermediate. The first monomer was the compound shown in formula (7) (IPDI), the second monomer was the compound shown in formula (11) (PBA), and n was 10. The first chain extender was dimethylolpropionic acid (DMPA), and the catalyst was dibutyltin dilaurate (DBTDL). Then, 0.696 g of 1,4-butanediol and 0.199 g of reversible covalent hydrazone glycol (PA) were added to the intermediate obtained above, and the reaction was continued for 1.5 h. The temperature was then adjusted to 40 °C to obtain the prepolymer. Triethanolamine (TEA) was added to the prepolymer for neutralization reaction for 30 min, followed by the addition of 50 mL of deionized water and stirring at 1000 r / min for 10 min to obtain an aqueous polyurethane with hydrazone bonds and a relative molecular mass of approximately 16456. Figure 1 The flowchart shows the entire preparation reaction of an aqueous polyurethane containing acylhydrazone bonds. The structural formula of the aqueous polyurethane containing acylhydrazone bonds is as follows:

[0094] Where -R2- is -R1- is

[0095] DMF was added to the aqueous polyurethane with acylhydrazone bonds obtained above, and then the water in the aqueous polyurethane with acylhydrazone bonds was removed by rotary evaporation to obtain an aqueous polyurethane solution with acylhydrazone bonds.

[0096] 301 mg FAI, 53.2 mg CsBr, 806.8 mg PbI2, and 91.8 mg PbBr2 were dissolved in a mixed solvent consisting of 1050 μL DMF and 150 μL DMSO to obtain a perovskite precursor solution. Then, the aqueous polyurethane solution with acylhydrazone bonds obtained above was added to obtain a doped perovskite precursor solution. The mass concentration of the aqueous polyurethane with acylhydrazone bonds in the doped perovskite precursor solution was 5 mg / mL.

[0097] FTO conductive glass with a sheet resistance of 15Ω, a transmittance of 85%, a size of 1.9cm×1.9cm, and a thickness of 500nm was selected as the transparent conductive substrate. The FTO conductive glass was ultrasonically treated with deionized water, acetone, and isopropanol in sequence, dried with nitrogen, and then cleaned by ultraviolet light irradiation for 30 minutes.

[0098] The hole transport layer precursor solution was spin-coated onto the treated FTO conductive glass at a spin speed of 3000 rpm for 30 s, and then annealed at 100 °C for 10 min to obtain a hole transport layer with a thickness of 30 nm. The hole transport layer precursor solution was an ethanol solution of MeO-2PACz with a concentration of 0.3 mg / mL.

[0099] The doped perovskite precursor solution obtained above was spin-coated onto the hole transport layer at a spin speed of 4000 rpm for 25 s. 350 μL of diethyl ether was added in the last 10 s of spin coating, followed by annealing at 100 °C for 60 min to obtain a perovskite light-absorbing layer with a thickness of 600 nm. The aqueous polyurethane with acylhydrazone bonds in the perovskite light-absorbing layer had a mass fraction of 0.5%.

[0100] The electron transport layer precursor solution was spin-coated onto the perovskite light-absorbing layer at a spin speed of 2000 rpm for 30 s, followed by annealing at 70 °C for 60 s to obtain an electron transport layer with a thickness of 100 nm. The electron transport layer precursor solution was PC with a concentration of 20 mg / mL. 61 BM's chlorobenzene solution.

[0101] The passivation layer precursor solution was spin-coated onto the electron transport layer at a spin speed of 4000 rpm for 30 s, and then annealed at 100 °C for 60 s to obtain a passivation layer with a thickness of 10 nm. The passivation layer precursor solution was a BCP isopropanol (IPA) solution with a concentration of 0.5 mg / mL.

[0102] An 80 nm thick Ag electrode layer was deposited on the passivation layer using a vacuum evaporation deposition apparatus. The vacuum degree of the vacuum evaporation deposition was 5 x 10⁻⁶. -4 Pa, evaporation rate of 0.8 A / s, effective cell area of ​​0.04 cm² 2 Perovskite solar cells were obtained.

[0103] Example 2

[0104] Compared with Example 1, the only difference is that in Example 2, in the process of preparing aqueous polyurethane with acylhydrazone bonds, the second monomer is the compound (PBA) shown in formula (11), and n is 20, while the rest are the same.

[0105] The relative molecular mass of the aqueous polyurethane with acylhydrazone bonds obtained in this embodiment is approximately 28,775.

[0106] Example 3

[0107] Compared with Example 1, the only difference is that in Example 3, in the process of preparing aqueous polyurethane with acylhydrazone bonds, the second monomer is the compound (PBA) shown in formula (11), and n is 6, while the rest are the same.

[0108] The relative molecular mass of the aqueous polyurethane with acylhydrazone bonds obtained in this embodiment is approximately 10643.

[0109] Example 4

[0110] Compared with Example 1, the only difference is that in Example 4, during the preparation of the aqueous polyurethane with acylhydrazone bonds, the mass concentration of the aqueous polyurethane with acylhydrazone bonds in the doped perovskite precursor solution is 2.5 mg / mL, and all other aspects are the same.

[0111] Example 5

[0112] Compared with Example 1, the only difference is that in Example 5, during the preparation of the aqueous polyurethane with acylhydrazone bonds, the mass concentration of the aqueous polyurethane with acylhydrazone bonds in the doped perovskite precursor solution is 10 mg / mL, and all other aspects are the same.

[0113] Comparative Example 1

[0114] Compared with Example 1, the only difference is that in Comparative Example 1, there was no preparation of aqueous polyurethane with acylhydrazone bonds and no step of adding aqueous polyurethane with acylhydrazone bonds to the perovskite precursor solution. All other aspects are the same, that is, the perovskite light-absorbing layer in the prepared perovskite solar cell does not contain aqueous polyurethane with acylhydrazone bonds.

[0115] Comparative Example 2

[0116] Compared with Example 1, the only difference is that in Comparative Example 2, an aqueous polyurethane elastomer with disulfide bonds is used instead of an aqueous polyurethane elastomer with hydrazone bonds. All other aspects are the same. The structural formula of the aqueous polyurethane elastomer with disulfide bonds is shown below:

[0117]

[0118] The products formed during the formation of the perovskite light-absorbing layer in the above embodiments and comparative examples are named perovskite thin films. The applicant characterized the performance of the perovskite thin films prepared in Example 1 and Comparative Example 1. Figure 2 The images show the XRD patterns of the perovskite films prepared in Example 1 and Comparative Example 1. Figure 3 The photoluminescence spectra of the perovskite thin films prepared in Example 1 and Comparative Example 1 are shown below. Figures 2-3 As can be seen, the addition of aqueous polyurethane with acylhydrazone bonds to the perovskite film improves the crystallinity and enhances the carrier transport capability.

[0119] The perovskite solar cells prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to photoelectric performance tests. Simultaneously, the perovskite solar cells prepared in Example 1 and Comparative Example 1 were tested for humidity stability and self-healing performance. Specific test contents and standards are shown below, and the test results are shown in Table 1. Figure 4-6 The test parameters and conditions are the same for all embodiments and comparative examples.

[0120] Photoelectric performance testing: Test conditions were as follows: at 25℃, a xenon lamp was used to simulate AM1.5 sunlight, with a light intensity of 100mW / cm². 2 When testing the current-voltage curve (JV) of perovskite solar cells, a reverse scan was performed from 1.2V to 0V at a scan rate of 20mV / s.

[0121] Humidity stability: The test method is as follows: The perovskite solar cell to be tested is stored in a sealed box at room temperature. Then, a saturated KCl aqueous solution is placed in the box to maintain the temperature at room temperature and the humidity at close to 85% to simulate the humidity of the perovskite solar cell under 85% humidity conditions. The changes in the efficiency of the perovskite solar cell are recorded at 6h, 14h, 20h, 33h and 70h during the storage process.

[0122] Self-healing performance test: The test method is as follows: The perovskite solar cell to be tested is bent around a cylinder with a diameter of 6 mm in a glove box, and the efficiency loss is recorded at 100, 400, 700, 1000, 1100, 1400, 1700 and 2000 times respectively. During this process, when bending to 1000 and 2000 times, the perovskite solar cell to be tested is heated on a hot stage at 60℃ for 10 minutes, and the efficiency change of the perovskite solar cell is recorded again.

[0123] Table 1. Photoelectric performance parameters of perovskite solar cells in the examples and comparative examples.

[0124] Example 1 1.15 23.83 81.52 22.36 Example 2 1.14 22.54 80.45 20.73 Example 3 1.14 22.44 80.19 20.54 Example 4 1.15 23.66 79.09 21.49 Example 5 1.17 23.37 80.23 21.89 Comparative Example 1 1.13 23.22 78.06 20.49 Comparative Example 2 1.14 23.32 78.14 20.78

[0125] From the data in Table 1 and the appendix Figure 4 It is evident that the perovskite solar cell using aqueous polyurethane with acylhydrazone bonds as an additive in this invention improves its JSC (current density), VOC (open-circuit voltage), FF (fill factor), and PCE (photovoltaic conversion efficiency). In particular, the photovoltaic conversion efficiency of the perovskite solar cell in the embodiment of this invention reaches a maximum of 22.36% from 20.49%, indicating that the addition of aqueous polyurethane with acylhydrazone bonds in this invention plays a role in improving the photoelectric performance of the perovskite solar cell.

[0126] from Figure 5 It can be seen that the moisture resistance of the perovskite solar cell in Example 1 of this invention is significantly improved. Specifically, the perovskite solar cell of Comparative Example 1 showed a significant efficiency reduction after 6 hours of storage in an 85% humidity environment, remaining at only about 60%, and further decreased to below 50% in the subsequent 14 and 20 hours; while the perovskite solar cell of Example 1 of this invention maintained an efficiency of 91% after 6 hours of storage in an 85% humidity environment, and remained stably above 90% until 20 hours, only showing a significant reduction after 33 hours. Therefore, the aqueous polyurethane with acylhydrazone bonds used in this invention can combine with uncoordinated anionic and cation defects in the perovskite absorber layer to form a dense, waterproof, and heat-insulating self-healing polymer film, which can, to a certain extent, slow down water erosion of the perovskite structure, allowing the perovskite solar cell of this invention to remain stable even in high humidity environments.

[0127] from Figure 6 As can be seen, the perovskite solar cell of the present invention initially shows almost no efficiency loss due to the introduction of aqueous polyurethane with acylhydrazone bonds. However, with the increase of bending cycles, the number of cracks and defects on the perovskite solar cell increases, and the efficiency loss becomes more significant. After 1000 bending cycles, the efficiency drops to 82%, but after heat treatment at 60°C for 30 minutes, the efficiency recovers to 96%, showing a significant recovery effect. When bent again for 400 cycles, the defects that could be restored by the aqueous polyurethane with acylhydrazone bonds reappear, along with other defects, causing a significant decrease in efficiency. After a total of 2000 bending cycles, the efficiency drops to 73%, but after reheat treatment, the efficiency can still recover to 80%. This shows that the introduction of aqueous polyurethane with acylhydrazone bonds can heal the defects caused by bending of the perovskite solar cell and restore efficiency. In contrast, Comparative Example 2 shows that the efficiency drops to 70% after 1000 bending cycles, and after heating at 60°C for 30 minutes, the efficiency does not change significantly. In contrast, the perovskite solar cell of this invention can self-repair at 50°C-60°C.

[0128] Therefore, the perovskite solar cell of the present invention can achieve self-repair at 50℃-60℃ by utilizing aqueous polyurethane with acylhydrazone bonds, thereby giving it excellent photoelectric conversion efficiency and stability.

[0129] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0130] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A perovskite solar cell, characterized in that, The material includes a perovskite light-absorbing layer, wherein the perovskite light-absorbing layer comprises an aqueous polyurethane having acylhydrazone bonds, and the structural formula of the aqueous polyurethane having acylhydrazone bonds is shown in formula (1) below. ； In equation (1), -R2- is selected from any one of the following equations: (2) - (5). 、 、 、 ， In equations (2) to (5), -R1- is selected from the following equation (6). , where n is selected from 5-25.

2. The perovskite solar cell according to claim 1, characterized in that, The aqueous polyurethane containing acylhydrazone bonds has a mass fraction of 0.1%-1% in the perovskite light-absorbing layer; And / or, the relative molecular mass of the aqueous polyurethane having acylhydrazone bonds is 10,000-30,000.

3. The perovskite solar cell according to claim 1, characterized in that, The perovskite material in the perovskite light-absorbing layer has the general structural formula ABX3, where A is selected from CH3NH3. + CH(NH2)2 + and Cs + At least one of them, B is selected from Pb 2+ Sn 2+ At least one of them, X is selected from Br - I - Cl - At least one of them.

4. The perovskite solar cell according to claim 1, characterized in that, It also includes a transparent conductive substrate layer, a hole transport layer, an electron transport layer, and a conductive electrode layer, wherein the transparent conductive substrate layer, the hole transport layer, the perovskite light absorption layer, the electron transport layer, and the conductive electrode layer are stacked sequentially to form an inverted perovskite solar cell.

5. The perovskite solar cell according to claim 4, characterized in that, It also includes a passivation layer disposed between the electron transport layer and the conductive electrode layer.

6. The perovskite solar cell according to claim 5, characterized in that, The thickness of the transparent conductive substrate layer is 100nm-1000nm, the thickness of the hole transport layer is 5nm-50nm, the thickness of the perovskite light absorption layer is 300nm-1000nm, the thickness of the electron transport layer is 20nm-200nm, the thickness of the passivation layer is 5nm-20nm, and the thickness of the conductive electrode layer is 50nm-1000nm.

7. A method for preparing a perovskite solar cell according to any one of claims 1-6, characterized in that, Includes the following steps: A hole transport layer is fabricated on a transparent conductive substrate; An aqueous polyurethane solution with acylhydrazone bonds is added to a perovskite precursor solution and mixed to obtain a doped perovskite precursor solution. The doped perovskite precursor solution is then placed on the surface of the hole transport layer and annealed to obtain a perovskite light absorption layer. An electron transport layer is fabricated on the perovskite light-absorbing layer; A conductive electrode layer is fabricated on the electron transport layer to obtain a perovskite solar cell.

8. The method for preparing a perovskite solar cell according to claim 7, characterized in that, The aqueous polyurethane with acylhydrazone bonds has a mass concentration of 0.01 mg / mL to 50 mg / mL in the doped perovskite precursor solution.

9. The method for preparing a perovskite solar cell according to claim 7, characterized in that, Before fabricating a conductive electrode layer on the electron transport layer, the method further includes the following step: fabricating a passivation layer on the electron transport layer.

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