Flexible perovskite solar cell and preparation method thereof

Abstract

The invention provides a flexible perovskite solar cell and a preparation method thereof. The flexible perovskite solar cell comprises a flexible conductive substrate, and a hole transport layer, a perovskite layer, an electron transport layer and a flexible electrode layer which are sequentially stacked on the flexible conductive substrate, the flexible electrode layer comprises a graphene / polymer composite material. In the flexible perovskite solar cell provided by the invention, the flexible electrode layer is the back electrode and is made of the graphene / polymer composite material, and the material has high conductivity, flexibility, adhesion and hydrophobicity, so that the flexible electrode layer has excellent comprehensive performance of high conductivity, high bending restorability, high adhesion and high hydrophobicity; the risk of electrode damage caused by bending can be reduced, and the performance of the flexible perovskite solar cell is improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology and relates to a flexible perovskite solar cell and its preparation method. Background Technology

[0003] The most significant characteristics of flexible perovskite solar cells (FPSCs) are their flexibility and resilience. Traditionally, resilience refers to a material's ability to deform under external force and recover from deformation after the force is removed. The resilience of an object is related to the inherent properties of the material. Therefore, obtaining highly resilient FPSCs requires specific requirements regarding chemical composition and fabrication methods. FPSCs consist of a flexible substrate, perovskite light-absorbing materials, charge-transporting materials, and a back electrode. Among these, the resilience of the back electrode is crucial for flexible devices. During bending, the back electrode is easily damaged, leading to a decrease in conductivity and separation between the back electrode and adjacent layers, resulting in performance degradation of the cell.

[0004] Therefore, it is urgent to improve the bend recoverability of the back electrode, reduce the risk of back electrode damage, and improve the performance of flexible perovskite solar cells. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a flexible perovskite solar cell and its fabrication method. In the flexible perovskite solar cell provided by the present invention, the flexible electrode layer serves as the back electrode, and its material is a graphene / polymer composite material. This material possesses high conductivity, flexibility, adhesion, and hydrophobicity, thereby enabling the flexible electrode layer to exhibit excellent comprehensive performance in terms of high conductivity, high bend recoverability, high adhesion, and high hydrophobicity. This reduces the risk of electrode damage caused by bending and improves the performance of the flexible perovskite solar cell.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a flexible perovskite solar cell, the flexible perovskite solar cell comprising a flexible conductive substrate, and a hole transport layer, a perovskite layer, an electron transport layer and a flexible electrode layer sequentially stacked on the flexible conductive substrate.

[0008] The flexible electrode layer includes a graphene / polymer composite material.

[0009] This invention provides a flexible perovskite solar cell, comprising a flexible conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a flexible electrode layer. The flexible electrode layer serves as the back electrode and is made of a graphene / polymer composite material. This material not only possesses high conductivity but also flexibility, thereby improving the bending recoverability of the electrode layer. Furthermore, the material exhibits strong adhesion, allowing it to adhere well to adjacent layers and reduce stress damage at the interface. In addition, the material is hydrophobic, giving the flexible electrode layer strong waterproofing capabilities, effectively inhibiting moisture intrusion into the perovskite and improving the cell's stability. In summary, the flexible electrode layer provided by this invention possesses excellent comprehensive performance characteristics, including high conductivity, high bending recoverability, high adhesion, and high hydrophobicity, which can reduce the risk of electrode damage caused by bending and improve the performance of flexible perovskite solar cells.

[0010] Preferably, in the graphene / polymer composite material, the polymer has the structural formula shown in Formula I:

[0011]

[0012] Where m ranges from 2 to 6, and m is an integer. For example, m can be 2, 3, 4, 5, or 6.

[0013] In the graphene / polymer composite material of the present invention, the polymer has the structural formula shown in Formula I, and there is a non-covalent interaction between the graphene and the polymer—a cation-π interaction, as shown in Formula I. Figure 1 As shown, this physical cross-linking endows the composite material with self-healing, plasticity, and spreadability. When m in the structural formula ranges from 2 to 6, the graphene / polymer composite material exhibits both high hydrophobicity and high electrical conductivity. This results in the graphene / polymer composite material possessing high electrical conductivity, flexibility, high bend recoverability, high adhesion, and high hydrophobicity.

[0014] Preferably, the range of m is 3-5, and more preferably 4-5.

[0015] In this invention, when m is preferably 4 or 5, the graphene / polymer composite material exhibits superior overall electrical conductivity and hydrophobicity.

[0016] Preferably, in the graphene / polymer composite material, the graphene sheet diameter is 2-8 μm, for example, it can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or 8 μm, etc., and the graphene thickness is 1-4 nm, for example, it can be 1 nm, 2 nm, 2.5 nm, 3 nm or 4 nm, etc., but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0017] In this invention, if the graphene sheet diameter in the graphene / polymer composite material is too small, the charge carriers cannot be effectively conducted between the graphene sheets, which will affect the transport of charge carriers; if the graphene sheet diameter is too large, it will affect the flexibility of the composite material and make it difficult to bend.

[0018] In graphene / polymer composites, the thinner the graphene, the easier it is for cracks to form during battery bending, which affects battery efficiency and promotes water and oxygen intrusion, affecting battery stability. Conversely, the thicker the graphene, the slower the carrier transport efficiency, further affecting efficiency.

[0019] Preferably, based on the total mass of the graphene / polymer composite material as 100%, the mass fraction of graphene is 0.5-5%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 2%.

[0020] In this invention, if the mass fraction of graphene is too small, the electrical conductivity of the composite material will be reduced; if the mass fraction of graphene is too large, the adhesion and flexibility of the composite material will be reduced.

[0021] Preferably, the thickness of the flexible electrode layer is 20-30 μm, for example, it can be 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm or 30 μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the flexible conductive substrate includes a substrate and an ITO film layer disposed on one side surface of the substrate, wherein the ITO film layer is in contact with the hole transport layer.

[0023] Preferably, the substrate material includes any one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or colorless polyimide (CPI).

[0024] Preferably, the hole transport layer includes p-type inorganic semiconductors and / or p-type organic semiconductors.

[0025] Preferably, the material of the p-type inorganic semiconductor includes NiO. x Any one or a combination of at least two of CuI or CuSCN.

[0026] Preferably, the material of the p-type organic semiconductor includes any one or a combination of at least two of the following: 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), [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [3-(9H-carbazole-9-yl)ethyl]phosphonic acid (3PACz), or [4-(9H-carbazole-9-yl)ethyl]phosphonic acid (4PACz).

[0027] Preferably, the thickness of the hole transport layer is 20-50nm, for example, it can be 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the perovskite layer comprises a perovskite material with the general formula ABX3, wherein A includes CH3NH3. + CH(NH2)2 + Cs + or Rb + B includes any one or at least two of the following, where B includes Pb. 2+ Sn 2+ Or Ge 2+ X includes any one or at least two of the following, X including Cl - ,Br - or I - Any one or at least two of them.

[0029] Preferably, the thickness of the perovskite layer is 400-700 nm, for example, it can be 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm or 700 nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the electron transport layer comprises an n-type inorganic semiconductor and / or an n-type organic semiconductor.

[0031] Preferably, the material of the n-type inorganic semiconductor includes C. 60 Any one or a combination of at least two of TiO2, SnO2, ZnO, or ZnO-ZnS.

[0032] Preferably, the material of the n-type organic semiconductor includes isomethyl [6,6]-phenyl-C61-butyrate (PCBM) and / or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).

[0033] Preferably, the thickness of the electron transport layer is 10-30 nm, for example, it can be 10 nm, 15 nm, 20 nm, 25 nm or 30 nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In a second aspect, the present invention provides a method for fabricating the flexible perovskite solar cell described in the first aspect, the method comprising:

[0035] A hole transport layer, a perovskite layer, an electron transport layer, and a flexible electrode layer are sequentially fabricated on a flexible conductive substrate to obtain the flexible perovskite solar cell.

[0036] The flexible electrode layer includes a graphene / polymer composite material.

[0037] Preferably, the preparation method of the graphene / polymer composite material includes:

[0038] (1) Mix graphite, polymer monomer, initiator and solvent to obtain a mixed solution;

[0039] (2) The mixed solution is placed under microwave conditions to carry out a polymerization reaction to obtain the graphene / polymer composite material.

[0040] In this invention, the microwave processing method is used to form cation-π interactions between the polymer and the graphene surface, forming a network structure in which graphene and polymer chains are cross-linked, while simultaneously exfoliating the graphite.

[0041] Preferably, the initiator includes V-50.

[0042] Preferably, the solvent includes water.

[0043] Preferably, the microwave is a single-mode microwave with a frequency of 1.5-4 GHz, such as 1.5 GHz, 2 GHz, 2.5 GHz, 3 GHz, 3.5 GHz, or 4 GHz, and a power of 25-35 W, such as 25 W, 26 W, 28 W, 30 W, 32 W, or 35 W, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] In this invention, if the microwave power is too low, the graphite will not be completely exfoliated, resulting in insufficient cation-π interaction between the polymer and the graphene surface; if the microwave power is too high, it will damage the overall structure of the composite material, leading to a reduction in flexibility and adhesion.

[0045] Preferably, the polymerization reaction temperature is 60-100℃, for example, 60℃, 70℃, 80℃, 90℃ or 100℃, and the polymerization reaction time is 120-160min, for example, 120min, 130min, 140min, 150min or 160min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the method for preparing the polymer monomer includes:

[0047] A solution containing the first monomer is added dropwise to a solution containing the second monomer, and the reaction is carried out for 2-5 days (e.g., 2, 3, 4, or 5 days) to obtain the polymer monomer; wherein the second monomer is 1-vinylimidazole, and the structural formula of the first monomer is shown in Formula II:

[0048]

[0049] Where m ranges from 2 to 6, and m is an integer.

[0050] In this invention, when m=2, the first monomer is 1,2-ethanesulfonate lactone; when m=3, the first monomer is 1,3-propanesulfonate lactone; when m=4, the first monomer is 1,4-butanesulfonate lactone; when m=5, the first monomer is 1,5-pentanesulfonate lactone; and when m=6, the first monomer is 1,6-hexanesulfonate lactone.

[0051] In this invention, the reaction of 1-vinylimidazole with a monomer having the structure of formula II is as shown in formula III:

[0052]

[0053] Preferably, the dripping is carried out under an inert atmosphere. The gas in the inert atmosphere includes nitrogen.

[0054] Preferably, the reaction is accompanied by stirring.

[0055] Preferably, the method for preparing the flexible electrode layer includes:

[0056] The graphene / polymer composite material is coated onto the surface of the electron transport layer and then annealed to obtain the flexible electrode layer.

[0057] Preferably, the coating method includes any one or a combination of at least two of spin coating, vapor deposition, blade coating, inkjet printing or screen printing, with blade coating or screen printing being preferred.

[0058] Preferably, the annealing temperature is 100-140℃, for example, 100℃, 110℃, 120℃, 130℃ or 140℃, and the annealing time is 20-40min, for example, 20min, 25min, 30min, 35min or 40min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, the hole transport layer is prepared by spin coating.

[0060] Preferably, the perovskite layer is prepared by spin coating.

[0061] Preferably, when preparing the perovskite layer by spin coating, the solvent used to prepare the perovskite precursor solution 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 (2-ME).

[0062] Preferably, the electron transport layer is prepared by vacuum evaporation.

[0063] 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.

[0064] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0065] This invention provides a flexible perovskite solar cell, comprising a flexible conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a flexible electrode layer. The flexible electrode layer serves as the back electrode and is made of a graphene / polymer composite material. This material not only possesses high conductivity but also flexibility, thereby improving the bending recoverability of the electrode layer. Furthermore, the material exhibits strong adhesion, allowing it to adhere well to adjacent layers and reduce stress damage at the interface. In addition, the material is hydrophobic, giving the flexible electrode layer strong waterproofing capabilities, effectively inhibiting moisture intrusion into the perovskite and improving the cell's stability. In summary, the flexible electrode layer provided by this invention possesses excellent comprehensive performance characteristics, including high conductivity, high bending recoverability, high adhesion, and high hydrophobicity, which can reduce the risk of electrode damage caused by bending and improve the performance of flexible perovskite solar cells. Attached Figure Description

[0066] Figure 1 This is a schematic diagram illustrating the interaction between graphene and polymers provided by the present invention.

[0067] Figure 2 These are stability test diagrams of the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 of this invention.

[0068] Figure 3 These are mechanical performance test diagrams of the flexible perovskite solar cells provided in Examples 1, 4-5, and Comparative Example 1 of this invention. Detailed Implementation

[0069] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0070] Example 1

[0071] This embodiment provides a flexible perovskite solar cell, which includes a flexible conductive substrate and a hole transport layer, a perovskite layer, an electron transport layer and a flexible electrode layer sequentially stacked on the flexible conductive substrate.

[0072] The flexible conductive substrate comprises a substrate and an ITO film layer disposed on one side surface of the substrate. The ITO film layer is in contact with the hole transport layer. The substrate is made of PEN material; the hole transport layer is made of PEDOT:PSS material with a thickness of 40 nm; the perovskite material in the perovskite layer has the chemical formula FA. 0.95 MA 0.05 PbI3, with a thickness of approximately 550 nm; the electron transport layer consists of sequentially stacked C... 60 It consists of a layer and a BCP layer, wherein the C 60 The layer is in contact with the perovskite layer, C 60The thickness of the layer is 20nm, and the thickness of the BCP layer is 8nm;

[0073] The flexible electrode layer is made of graphene / polymer composite material, wherein the graphene sheet diameter is 5 μm, the graphene thickness is 2 nm, and the polymer structure is as follows: m=3, with the total mass of the graphene / polymer composite material being 100%, the mass fraction of graphene is 2%, and the thickness of the flexible electrode layer is 25μm.

[0074] This embodiment also provides a method for fabricating the above-mentioned flexible perovskite solar cell, the method comprising:

[0075] (1) The flexible conductive substrate was cleaned by ultrasonic cleaning with detergent, deionized water, acetone and anhydrous ethanol respectively, and then dried with a nitrogen gun; the ultrasonic cleaning power was 100 Hz and the ultrasonic cleaning time was 15 min.

[0076] (2) A PEDOT:PSS solution with a concentration of 65 mg / mL was dropped onto the cleaned flexible conductive substrate and spin-coated at a speed of 5000 rpm for 50 s to obtain a hole transport layer.

[0077] (3) Dissolve MAI, FAI, MACl, and PbI2 in a mixed solvent composed of dimethyl sulfoxide and dimethylformamide. Heat at 70°C and stir continuously for 1 hour to ensure complete dissolution, thus obtaining a perovskite precursor solution. The concentration ratio of FAI:MAI:MACl is 0.95:0.05:0.14, the concentrations of FAI and PbI2 are both 1.5 mol / L, and the volume ratio of dimethyl sulfoxide to dimethylformamide in the mixed solvent is 1:9. Spin-coat the perovskite precursor solution onto the hole transport layer at 5000 rpm for 50 seconds. During this time, iodine ions and lead ions will penetrate into the hole transport layer, further forming a double cross-linked network gel. Finally, anneal at 120°C for 15 minutes to crystallize and form a perovskite layer with a thickness of approximately 550 nm, i.e., FA... 0.95 MA 0.05 PbI3 perovskite light-absorbing layer;

[0078] (4) C is deposited on the surface of the perovskite layer by vacuum evaporation. 60 The layer, the vapor deposition is carried out under a vacuum of 5×10 -4 The evaporation was carried out at Pa, with an evaporation rate of 0.15 A / s and a thickness of approximately 20 nm; at C 60 A hole-blocking BCP layer is deposited on the surface of the layer by vacuum evaporation, wherein the evaporation is performed at a vacuum degree of 5 × 10⁻⁶. -4The process was carried out under Pa conditions, with an evaporation rate of 0.2 A / s and a thickness of approximately 8 nm, thus obtaining an electron transport layer.

[0079] (5) Dissolve 9.41 g of 1-vinylimidazol in 60 mL of acetone to prepare a 1-vinylimidazol solution, and dissolve 0.1 mol of 1,3-propanesulfonic acid lactone in 40 mL of acetone to prepare a 1,3-propanesulfonic acid lactone solution. Then, under a nitrogen atmosphere at 0 °C, add the 1,3-propanesulfonic acid lactone solution dropwise into the 1-vinylimidazol solution. After stirring at room temperature (25 °C) for 3 days, filter the solution, wash it with acetone at least three times, and vacuum dry it at room temperature (25 °C) to obtain the polymer monomer.

[0080] Graphite, 30 mmol of polymer monomer and 0.05 mmol of V-50 initiator were dispersed in 10 mL of deionized water. The resulting mixture was transferred to a microwave reaction vessel and sealed. The vessel was then placed in a microwave reactor with a working frequency of 2.45 GHz and irradiated with 30 W using a single-mode microwave device. The reaction vessel was heated to 80 °C and maintained for 20 min, and then kept at 80 °C for 120 min to prepare the graphene / polymer composite material.

[0081] Graphene / polymer composite material was coated onto the BCP layer by a blade coating method. The blade was 220 μm away from the substrate and the blade speed was 5 cm / s. The coating was then annealed at 120 °C for 30 min to obtain a flexible electrode layer with a thickness of approximately 25 μm.

[0082] Example 2

[0083] This embodiment provides a flexible perovskite solar cell. The difference from Embodiment 1 is that in the graphene / polymer composite material, m in the polymer structural formula is adjusted to 4, while the other parameters remain the same as in Embodiment 1.

[0084] This embodiment also provides a method for preparing the above-mentioned flexible perovskite solar cell. The difference from Example 1 is that 1,3-propanesulfonic acid lactone is replaced with an equal amount of 1,4-butanesulfonic acid lactone, while the rest of the preparation method and parameters are the same as in Example 1.

[0085] Example 3

[0086] This embodiment provides a flexible perovskite solar cell. The difference from Embodiment 1 is that in the graphene / polymer composite material, the m in the polymer structural formula is adjusted to 5, while the other parameters remain the same as in Embodiment 1.

[0087] This embodiment also provides a method for preparing the above-mentioned flexible perovskite solar cell. The difference from Example 1 is that 1,3-propanesulfonic acid lactone is replaced with an equal amount of 1,5-pentanesulfonic acid lactone, while the rest of the preparation method and parameters are the same as in Example 1.

[0088] Example 4

[0089] This embodiment provides a flexible perovskite solar cell. The difference from Embodiment 1 is that in the graphene / polymer composite material, the m in the polymer structural formula is adjusted to 2, while the other parameters remain the same as in Embodiment 1.

[0090] This embodiment also provides a method for preparing the above-mentioned flexible perovskite solar cell. The difference from Example 1 is that 1,3-propanesulfonic acid lactone is replaced with an equal amount of 1,2-ethanesulfonic acid lactone, while the rest of the preparation method and parameters are the same as in Example 1.

[0091] Example 5

[0092] This embodiment provides a flexible perovskite solar cell. The difference from Embodiment 1 is that in the graphene / polymer composite material, the m in the polymer structural formula is adjusted to 6, while the other parameters remain the same as in Embodiment 1.

[0093] This embodiment also provides a method for preparing the above-mentioned flexible perovskite solar cell. The difference from Example 1 is that 1,3-propanesulfonic acid lactone is replaced with an equal amount of 1,6-hexanesulfonic acid lactone, while the rest of the preparation method and parameters are the same as in Example 1.

[0094] Example 6

[0095] This embodiment provides a flexible perovskite solar cell, which includes a flexible conductive substrate and a hole transport layer, a perovskite layer, an electron transport layer and a flexible electrode layer sequentially stacked on the flexible conductive substrate.

[0096] The flexible conductive substrate comprises a substrate and an ITO film layer disposed on one side surface of the substrate. The ITO film layer is in contact with the hole transport layer. The substrate is made of PEN material; the hole transport layer is made of PEDOT:PSS material with a thickness of 40 nm; the perovskite material in the perovskite layer has the chemical formula FA. 0.95 MA 0.05 PbI3, with a thickness of approximately 550 nm; the electron transport layer consists of sequentially stacked C... 60 It consists of a layer and a BCP layer, wherein the C 60 The layer is in contact with the perovskite layer, C 60 The thickness of the layer is 20nm, and the thickness of the BCP layer is 8nm;

[0097] The flexible electrode layer is made of graphene / polymer composite material, wherein the graphene sheet diameter is 2μm, the graphene thickness is 4nm, and the polymer structure is as follows: m=3, with the total mass of the graphene / polymer composite material being 100%, the mass fraction of graphene is 3%, and the thickness of the flexible electrode layer is 28μm.

[0098] This embodiment also provides a method for fabricating the above-mentioned flexible perovskite solar cell, the method comprising:

[0099] (1) The flexible conductive substrate was cleaned by ultrasonic cleaning with detergent, deionized water, acetone and anhydrous ethanol respectively, and then dried with a nitrogen gun; the ultrasonic cleaning power was 100 Hz and the ultrasonic cleaning time was 15 min.

[0100] (2) A PEDOT:PSS solution with a concentration of 65 mg / mL was dropped onto the cleaned flexible conductive substrate and spin-coated at a speed of 5000 rpm for 50 s to obtain a hole transport layer.

[0101] (3) Dissolve MAI, FAI, MACl, and PbI2 in a mixed solvent composed of dimethyl sulfoxide and dimethylformamide. Heat at 70°C and stir continuously for 1 hour to ensure complete dissolution, thus obtaining a perovskite precursor solution. The concentration ratio of FAI:MAI:MACl is 0.95:0.05:0.14, the concentrations of FAI and PbI2 are both 1.5 mol / L, and the volume ratio of dimethyl sulfoxide to dimethylformamide in the mixed solvent is 1:9. Spin-coat the perovskite precursor solution onto the hole transport layer at 5000 rpm for 50 seconds. During this time, iodine ions and lead ions will penetrate into the hole transport layer, further forming a double cross-linked network gel. Finally, anneal at 120°C for 15 minutes to crystallize and form a perovskite layer with a thickness of approximately 550 nm, i.e., FA... 0.95 MA 0.05 PbI3 perovskite light-absorbing layer;

[0102] (4) C is deposited on the surface of the perovskite layer by vacuum evaporation. 60 The layer, the vapor deposition is carried out under a vacuum of 5×10 -4 The evaporation was carried out at Pa, with an evaporation rate of 0.15 A / s and a thickness of approximately 20 nm; at C 60 A hole-blocking BCP layer is deposited on the surface of the layer by vacuum evaporation, wherein the evaporation is performed at a vacuum degree of 5 × 10⁻⁶. -4 The process was carried out under Pa conditions, with an evaporation rate of 0.2 A / s and a thickness of approximately 8 nm, thus obtaining an electron transport layer.

[0103] (5) Dissolve 9.41 g of 1-vinylimidazol in 60 mL of acetone to prepare a 1-vinylimidazol solution, and dissolve 0.1 mol of 1,3-propanesulfonic acid lactone in 40 mL of acetone to prepare a 1,3-propanesulfonic acid lactone solution. Then, under a nitrogen atmosphere at 0 °C, add the 1,3-propanesulfonic acid lactone solution dropwise into the 1-vinylimidazol solution. After stirring at room temperature (25 °C) for 3 days, filter the solution, wash it with acetone at least three times, and vacuum dry it at room temperature (25 °C) to obtain the polymer monomer.

[0104] Graphite, 30 mmol of polymer monomer and 0.05 mmol of V-50 initiator were dispersed in 10 mL of deionized water. The resulting mixture was transferred to a microwave reaction vessel and sealed. The vessel was then placed in a microwave reactor with a working frequency of 2.45 GHz and irradiated with 30 W using a single-mode microwave device. The reaction vessel was heated to 80 °C and maintained for 20 min, and then kept at 80 °C for 140 min to prepare the graphene / polymer composite material.

[0105] Graphene / polymer composite material was coated onto the BCP layer by a blade coating method. The blade was 220 μm away from the substrate and the blade speed was 5 cm / s. The coating was then annealed at 120 °C for 30 min to obtain a flexible electrode layer with a thickness of approximately 25 μm.

[0106] Example 7

[0107] The difference between this embodiment and Example 1 is that the graphene sheet diameter in the graphene / polymer composite material is 1.5 μm, while the rest of the preparation methods and parameters are the same as in Example 1.

[0108] Example 8

[0109] The difference between this embodiment and Example 1 is that the graphene sheet diameter in the graphene / polymer composite material is 8.5 μm, while the rest of the preparation methods and parameters are the same as in Example 1.

[0110] Example 9

[0111] The difference between this embodiment and Example 1 is that the thickness of the graphene in the graphene / polymer composite material is 0.5 nm, while the rest of the preparation methods and parameters are the same as in Example 1.

[0112] Example 10

[0113] The difference between this embodiment and Example 1 is that the thickness of the graphene in the graphene / polymer composite material is 4.5 nm, while the rest of the preparation methods and parameters are the same as in Example 1.

[0114] Example 11

[0115] The difference between this embodiment and Embodiment 1 is that, based on the total mass of the graphene / polymer composite material being 100%, the mass fraction of graphene is 0.2%, while the remaining preparation methods and parameters remain the same as in Embodiment 1.

[0116] Example 12

[0117] This embodiment provides a flexible perovskite solar cell. The difference from Embodiment 1 is that, based on the total mass of the graphene / polymer composite material as 100%, the mass fraction of graphene is 5.5%, while the remaining preparation methods and parameters are consistent with those of Embodiment 1.

[0118] Example 13

[0119] The difference between this embodiment and Embodiment 1 is that the microwave power is adjusted to 20W in the method for preparing graphene / polymer composite materials, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0120] Example 14

[0121] The difference between this embodiment and Embodiment 1 is that the microwave power is adjusted to 40W in the method for preparing graphene / polymer composite materials, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 1 is that step (5) is replaced by "applying carbon paste to the BCP layer by scraping, with the scraper 220 μm away from the substrate and the scraper speed 5 cm / s, and then annealing at 100°C for 20 min to obtain a flexible electrode layer with a thickness of about 25 μm", that is, replacing the graphene / polymer composite material with graphite, while the rest of the preparation methods and parameters are the same as in Example 1.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is that graphene is omitted, and the material of the flexible electrode layer is a polymer. The rest of the preparation methods and parameters are the same as those in Example 1.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is that the polymer is omitted, and the material of the flexible electrode layer is graphene. The rest of the preparation methods and parameters are the same as those in Example 1.

[0128] Performance testing

[0129] (1) Photovoltaic performance tests were conducted on the flexible perovskite solar cells provided in Examples 1-14 and Comparative Examples 1-3:

[0130] The test area is 1cm. 2 ;

[0131] The test conditions for photoelectric performance were: AM1.5, 1000W / m 2 , 25±2℃.

[0132] The test results are shown in Table 1.

[0133] (2) Stability tests were conducted on the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1:

[0134] The flexible perovskite solar cell was not encapsulated and placed in a glove box for 1000 hours. During this period, PCE tests were performed on the flexible perovskite solar cell every 100 hours, and the test conditions were as shown in test (1). Then, the data were normalized, and the results were as follows. Figure 2 As shown.

[0135] from Figure 2 It can be seen that the flexible perovskite solar cell provided by this invention has significantly improved stability, maintaining approximately 90% of its initial value after 1000 hours, while solar cells prepared using ordinary graphite electrodes exhibit faster degradation. This is because the flexible electrode also possesses strong waterproof capabilities, effectively inhibiting moisture intrusion into the perovskite and improving cell stability. Furthermore, as the carbon chain number gradually increases, the cell stability gradually improves. This is because long-chain alkyl polymers have better hydrophobicity, resulting in a more significant effect on moisture isolation and thus better stability.

[0136] (3) Mechanical performance tests were conducted on the flexible perovskite solar cells provided in Examples 1, 4-5, and Comparative Example 1. The specific test steps included:

[0137] The flexible perovskite solar cell was bent 3000 times with a bending radius of 5 mm. During this period, PCE tests were performed on the flexible perovskite solar cell after every 500 bends. The test conditions are shown in test (1). Then, the test results were normalized. The normalized results are shown in the figure. Figure 3 As shown.

[0138] from Figure 3 As can be seen, the mechanical properties of the flexible perovskite solar cell provided by the present invention are significantly improved. This is because the flexible electrode in the perovskite solar cell has strong self-healing, plasticity and adhesion, and can adhere well to adjacent layers, reducing stress damage between interfaces.

[0139] Table 1

[0140] Voc(V) <![CDATA[Jsc(mA / cm 2 )]]> FF (%) PCE (%) Example 1 1.05 24.3 74.6 19.0 Example 2 1.03 24.5 74.4 18.8 Example 3 1.04 24.0 74.3 18.6 Example 4 1.05 24.5 74.3 19.1 Example 5 1.04 23.9 73.7 18.3 Example 6 1.05 24.1 74.9 19.0 Example 7 1.02 22.9 73.5 17.2 Example 8 1.03 23.2 73.4 17.5 Example 9 1.03 23.1 73.2 17.4 Example 10 1.02 23.5 72.9 17.5 Example 11 1.01 22.8 73.9 17.0 Example 12 1.01 23 73.7 17.1 Example 13 1.02 23.3 72.5 17.2 Example 14 1.01 23.1 73.1 17.1 Comparative Example 1 1.00 22.8 72.1 16.4 Comparative Example 2 0.97 22.5 72.4 15.8 Comparative Example 3 0.98 23.4 72.2 16.6

[0141] analyze:

[0142] As can be seen from Examples 1-6 in Table 1, the perovskite solar cells with flexible electrode layers provided by the present invention exhibit significant improvements in open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and power conversion efficiency (PCE). The flexible electrode layer has high conductivity, thus improving the cell's light conversion efficiency.

[0143] As can be seen from Examples 1 and 7-8, if the graphene sheet diameter in the graphene / polymer composite material is too small, the charge carriers cannot be well conducted between the graphene sheets, which will affect the transport of charge carriers and reduce the photoelectric conversion efficiency; if the graphene sheet diameter in the graphene / polymer composite material is too large, it will affect the flexibility of the composite material, making it difficult to bend, and the photoelectric conversion efficiency will also decrease.

[0144] As can be seen from Examples 1 and 9-10, if the thickness of graphene in the graphene / polymer composite material is too small, the photoelectric conversion efficiency of the perovskite solar cell will decrease; if the thickness of graphene in the graphene / polymer composite material is too large, the carrier transport efficiency will slow down, affecting the photoelectric conversion efficiency.

[0145] As can be seen from Examples 1 and 11-12, if the mass fraction of graphene is too small, the conductivity of the composite material will be reduced, affecting the photoelectric conversion efficiency; if the mass fraction of graphene is too large, the photoelectric conversion efficiency of the perovskite solar cell will decrease.

[0146] As can be seen from Examples 1 and 13-14, if the microwave power is too low, the graphite will not be completely exfoliated, resulting in insufficient cation-π interaction between the polymer and the graphene surface, which affects the photoelectric conversion efficiency; if the microwave power is too high, it will damage the overall structure of the composite material and affect the photoelectric conversion efficiency.

[0147] As can be seen from Example 1 and Comparative Example 1, if the graphene / polymer composite material is replaced with graphite, the cation-π interaction cannot be formed in the composite material, and the photoelectric conversion efficiency decreases significantly.

[0148] As can be seen from Example 1 and Comparative Example 2, if graphene is omitted and the material of the flexible electrode layer is a polymer, the conductivity of the composite material will decrease significantly and the photoelectric conversion efficiency will decrease significantly.

[0149] As can be seen from Example 1 and Comparative Example 3, if the polymer is omitted and the material of the flexible electrode layer is graphene, the photoelectric conversion efficiency of the perovskite solar cell will decrease significantly.

[0150] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A flexible perovskite solar cell, characterized in that, The flexible perovskite solar cell includes a flexible conductive substrate, and a hole transport layer, a perovskite layer, an electron transport layer and a flexible electrode layer sequentially stacked on the flexible conductive substrate. The flexible electrode layer includes a graphene / polymer composite material.

2. The flexible perovskite solar cell according to claim 1, characterized in that, In the graphene / polymer composite material, the polymer has the structural formula shown in Formula I: Where m ranges from 2 to 6, and m is an integer.

3. The flexible perovskite solar cell according to claim 2, characterized in that, The range of m is 3-5.

4. The flexible perovskite solar cell according to claim 1, characterized in that, In the graphene / polymer composite material, the graphene sheet diameter is 2-8 μm and the graphene thickness is 1-4 nm. Based on the total mass of the graphene / polymer composite material being 100%, the mass fraction of graphene is 0.5-5%.

5. The flexible perovskite solar cell according to claim 1, characterized in that, The thickness of the flexible electrode layer is 20-30 μm.

6. The flexible perovskite solar cell according to claim 1, characterized in that, The thickness of the hole transport layer is 20-50 nm; The thickness of the perovskite layer is 400-700 nm; The thickness of the electron transport layer is 10-30 nm.

7. A method for fabricating a flexible perovskite solar cell according to any one of claims 1-6, characterized in that, The preparation method includes: A hole transport layer, a perovskite layer, an electron transport layer, and a flexible electrode layer are sequentially fabricated on a flexible conductive substrate to obtain the flexible perovskite solar cell. The flexible electrode layer includes a graphene / polymer composite material.

8. The preparation method according to claim 7, characterized in that, The preparation method of the graphene / polymer composite material includes: (1) Mix graphite, polymer monomer, initiator and solvent to obtain a mixed solution; (2) The mixed solution is placed under microwave conditions to carry out a polymerization reaction to obtain the graphene / polymer composite material; The microwave is a single-mode microwave with a frequency of 1.5-4 GHz and a power of 25-35 W. The polymerization reaction is carried out at a temperature of 60-100℃ for a duration of 120-160 min.

9. The preparation method according to claim 8, characterized in that, The method for preparing the polymer monomer includes: The solution containing the first monomer is added dropwise to the solution of the second monomer, and the reaction is carried out for 2-5 days to obtain the polymer monomer; wherein the second monomer is 1-vinylimidazole, and the structural formula of the first monomer is shown in Formula II: Where m ranges from 2 to 6, and m is an integer.

10. The preparation method according to claim 7, characterized in that, The method for preparing the flexible electrode layer includes: The graphene / polymer composite material is coated onto the surface of the electron transport layer and then annealed to obtain the flexible electrode layer. The annealing temperature is 100-140℃, and the annealing time is 20-40 minutes.

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