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 substrate layer, a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole barrier layer and an electrode layer which are sequentially stacked. And the composite gel layer is prepared from composite gel of poly (N-acryloyl-2-glycine) and chitosan. The flexible perovskite solar cell provided by the invention has high flexibility, high mechanical performance, high photoelectric conversion efficiency and high stability.

Description

Technical Field

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

[0002] In recent years, with the rise of wearable and self-powered flexible electronic products, the market demand for flexible perovskite solar cells (FPSCs) has been increasing. This is mainly attributed to the characteristics of perovskite thin films, such as low-temperature fabrication, light weight, flexibility, and compatibility with various curved surfaces.

[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, electrodes, perovskite light-absorbing materials, and charge-transport materials. The quality of the perovskite light-absorbing material film determines the photoelectric performance of the FPSC. However, unlike rigid perovskite solar cells, FPSCs require repeated stretching and bending, thus necessitating elasticity. The polycrystalline structure of perovskite materials makes them brittle, and grain boundaries are easily disrupted. Especially during bending, the perovskite layer develops cracks of varying degrees, which generate free electron-hole recombination centers. Higher electron-hole recombination center density leads to lower carrier lifetime, consequently reducing device efficiency and stability.

[0004] Therefore, there is an urgent need to develop a flexible perovskite solar cell with high flexibility, high photoelectric conversion efficiency, and high stability. 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, wherein the flexible perovskite solar cell possesses high flexibility, high mechanical properties, high photoelectric conversion efficiency, and high stability.

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

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

[0008] The composite gel layer comprises a composite gel of poly(N-acryloyl-2-glycine) (PACG) and chitosan (CS).

[0009] In this invention, a composite gel of poly(N-acryloyl-2-glycine) and chitosan is used as the composite gel layer to connect with the perovskite layer. The composite gel of poly(N-acryloyl-2-glycine) and chitosan possesses excellent mechanical properties. The carboxyl groups in the composite gel layer are bonded to halide anions via hydrogen bonds, and the carboxyl groups in the composite gel layer can interact with Pb through strong electrostatic interactions. 2+ Sn 2+ Or Ge 2+ In combination, the aforementioned interactions between the composite gel layer and the perovskite layer effectively suppress ion migration, reduce the Young's modulus of the perovskite film in the perovskite layer, and improve the flexibility of the flexible perovskite solar cell, thereby enhancing its bending performance. Furthermore, the carboxyl groups in the composite gel layer interact with halide anions (e.g., I-) through hydrogen bonds. - The combination of these elements effectively suppresses ion migration and enhances the stability of flexible perovskite solar cells; the carboxylate groups in the composite gel layer can react with Pb through strong electrostatic interactions. 2+ Sn 2+ Or Ge 2+ Combined, capturing Pb 2+ Sn 2+ Or Ge 2+ This effectively suppresses the leakage of Pb, Sn, or Ge after deformation and damage to flexible perovskite solar cells; in addition, the amide groups and carboxyl groups contained in the composite gel layer can effectively passivate defects in the perovskite, significantly improving the photoelectric conversion efficiency of flexible perovskite solar cells.

[0010] Preferably, the substrate layer comprises ITO glass and a flexible substrate.

[0011] Preferably, the flexible substrate comprises any one of polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, or colorless polyimide (CPI) film.

[0012] Preferably, the hole transport layer comprises p-type inorganic semiconductor material and / or p-type organic semiconductor material.

[0013] Preferably, the p-type inorganic semiconductor material includes any one or a combination of at least two of copper sulfide, nickel oxide, molybdenum oxide, cuprous iodide (CuI), or cuprous thiocyanate (CuSCN).

[0014] Preferably, the p-type organic semiconductor material 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).

[0015] Preferably, the perovskite layer comprises a perovskite material.

[0016] Preferably, the perovskite material is ABX3, wherein A is CH3NH3. + CH(NH2)2 + Cs + or Rb + B is any combination of one or at least two of the following, where B is Pb. 2+ Sn 2+ Or Ge 2+ Any combination of one or at least two of them, X is Cl - ,Br - Or I - Any one or at least two of them.

[0017] Preferably, the electron transport layer comprises an n-type inorganic semiconductor material and / or an n-type organic semiconductor material.

[0018] Preferably, the n-type inorganic semiconductor material includes any one or a combination of at least two of TiO2, SnO2, ZnO, or ZnO-ZnS.

[0019] Preferably, the n-type organic semiconductor material includes C 60 and / or [6,6]-phenyl-C 61 1-Methyl butyrate (PCBM).

[0020] Preferably, the hole-blocking layer comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).

[0021] Preferably, the electrode layer comprises any one of Au, Ag, Al, or low-temperature carbon.

[0022] In this invention, the low-temperature carbon refers to graphite or graphene, and the low temperature in the low-temperature carbon is 100-130℃, such as 105℃, 110℃, 115℃, 120℃ or 125℃.

[0023] Preferably, the thickness of the flexible substrate is 2-50 μm, such as 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 45 μm.

[0024] Preferably, the thickness of the ITO glass is 100-150nm, such as 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm or 145nm.

[0025] Preferably, the thickness of the hole transport layer is 10-300nm, such as 50nm, 100nm, 150nm, 200nm or 250nm.

[0026] Preferably, the thickness of the composite gel layer is 1-5 nm, such as 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm or 4.5 nm.

[0027] Preferably, the thickness of the perovskite layer is 400-700 nm, such as 430 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm or 680 nm.

[0028] In this invention, the thickness of the composite gel layer is 1-5 nm, resulting in a more efficient flexible perovskite solar cell. If the composite gel layer is too thick, it will inhibit carrier transport and reduce photoelectric conversion efficiency; if the thickness is too thin, it cannot effectively suppress defects on the perovskite surface, and its effect on improving flexibility and bending performance is limited.

[0029] Preferably, the thickness of the electron transport layer is 10-50nm, such as 15nm, 20nm, 25nm, 30nm, 35nm, 40nm or 45nm.

[0030] Preferably, the thickness of the hole blocking layer is 3-15nm, such as 5nm, 7nm, 9nm, 11nm or 13nm.

[0031] Preferably, the thickness of the electrode layer is 80-100nm, such as 81nm, 82nm, 83nm, 84nm, 85nm, 86nm, 87nm, 88nm or 89nm.

[0032] In a second aspect, the present invention provides a method for fabricating a flexible perovskite solar cell as described in the first aspect, the method comprising the following steps: sequentially fabricating a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole blocking layer, and an electrode layer on a substrate layer to obtain the flexible perovskite solar cell.

[0033] Preferably, the specific preparation method of the composite gel layer and perovskite layer includes the following steps:

[0034] (1) N-acryloyl-2-glycine (ACG), chitosan, crosslinking agent, photoinitiator and water are mixed to form a solution, which is then coated on the hole transport layer and irradiated with ultraviolet light (UV) to obtain the composite gel layer.

[0035] (2) Mix the perovskite material and solvent, coat it onto the composite gel layer obtained in step (1), and heat it to obtain the perovskite layer.

[0036] In this invention, under the combined effects of ultraviolet light, crosslinking agent, and photoinitiator, N-acryloyl-2-glycine undergoes free radical polymerization to form polyN-acryloyl-2-glycine, with short-chain chitosan also embedded therein, resulting in a composite gel (CS / PACG) of polyN-acryloyl-2-glycine and chitosan. Subsequently, a mixed solution of perovskite material and solvent is coated onto the composite gel layer obtained in step (1). During this process, halogen anions and Pb... 2+ Sn 2+ Or Ge 2+ It penetrates into the composite gel layer and acts as a crosslinking agent to form amino anionic and carboxyl cationic domains within the composite gel layer. The halogen anions initiate polymer salting out, leading to the spontaneous collapse of chitosan chains and the formation of a chain entanglement network; the carboxyl groups interact with Pb... 2+ Sn 2+ Or Ge 2+ Strong electrostatic interactions between them induce ionic crosslinking of PACG, thereby forming a double crosslinked network.

[0037] Preferably, the crosslinking agent comprises N,N′-methylenebisacrylamide (MBA).

[0038] Preferably, the photoinitiator includes photoinitiator 2595.

[0039] Preferably, the solution in step (1) comprises the following components by mass parts: 0.4-0.6 parts of N-acryloyl-2-glycine (e.g., 0.42, 0.44, 0.46, 0.48, 0.5, 0.52, 0.54, 0.56 or 0.58 parts, etc.), 0.02-0.2 parts of chitosan (e.g., 0.05, 0.08, 0.11, 0.14 or 0.17 parts, etc.), and 3-5 parts of water (e.g., 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6 or 4.8 parts, etc.).

[0040] Preferably, the molar amount of the crosslinking agent is 0.01%-0.05% of the molar amount of N-acryloyl-2-glycine, for example, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, or 0.045%.

[0041] Preferably, the molar amount of the photoinitiator accounts for 0.5%-2% of the molar amount of N-acryloyl-2-glycine, for example, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7% or 1.9%.

[0042] Preferably, the wavelength of the ultraviolet light irradiation is 300-380nm (e.g., 310nm, 320nm, 330nm, 340nm, 350nm, 360nm or 370nm, etc.), and the irradiation time is 1-2h, e.g., 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h or 1.9h, etc.

[0043] Preferably, the solvent in step (2) includes any one or a combination of at least two of N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolinone, dimethylacetamide, N,N-dimethylpropenylurea, acetonitrile or 2-mercaptoethanol.

[0044] In this invention, the solvent of the solution in step (1) is water, and the solvent of the solution in step (2) is an organic phase. The preparation of the composite gel layer and perovskite layer bilayer structure can solve the problem that the organic phase and water are immiscible, and at the same time will not cause water to destroy the nucleation of perovskite.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] In this invention, a composite gel of poly(N-acryloyl-2-glycine) and chitosan is used as a composite gel layer to connect with the perovskite layer. This composite gel not only possesses excellent mechanical properties, reducing the Young's modulus of the perovskite layer and improving the flexibility of the flexible perovskite solar cell, but also, the carboxyl groups in the composite gel layer bind to the halide anions in the perovskite layer through hydrogen bonds, effectively inhibiting ion migration and enhancing the stability of the flexible perovskite solar cell. Simultaneously, the carboxyl groups in the composite gel layer can interact with Pb through strong electrostatic interactions. 2+ Sn 2+ Or Ge 2+ Combined, capturing Pb 2+ Sn 2+ Or Ge 2+ This effectively suppresses the leakage of Pb, Sn, or Ge after deformation and damage to flexible perovskite solar cells; in addition, the amide groups and carboxyl groups contained in the composite gel layer can effectively passivate defects in the perovskite, significantly improving the photoelectric conversion efficiency of flexible perovskite solar cells. Attached Figure Description

[0047] Figure 1 The carboxyl groups in the composite gel layer and the I groups in the perovskite layer of the flexible perovskite solar cell provided in Example 1 - A schematic diagram of the mechanism of action;

[0048] Figure 2 The carboxylate and Pb groups in the composite gel layer of the flexible perovskite solar cell provided in Example 1 2+ A schematic diagram of the mechanism of action;

[0049] Figure 3 XRD comparison images of the perovskite layers provided in Example 1 and Comparative Example 1;

[0050] Figure 4 Comparison of the ultraviolet spectra of the perovskite layers provided in Example 1 and Comparative Example 1;

[0051] Figure 5 Comparison of fluorescence spectra of perovskite layers provided in Example 1 and Comparative Example 1;

[0052] Figure 6 Stability comparison diagrams of flexible perovskite solar cells provided in Examples 1, 8-11 and Comparative Examples 1-3;

[0053] Figure 7 Comparison of the flexibility of flexible perovskite solar cells provided in Examples 1, 8-11 and Comparative Examples 1-3;

[0054] Figure 8A comparison chart showing the lead concentration in the aqueous solutions formed after the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 were immersed in the same mass of water for 8 hours. Detailed Implementation

[0055] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0056] Example 1

[0057] This embodiment provides a flexible perovskite solar cell and its fabrication method. The flexible perovskite solar cell includes a substrate layer, a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole blocking layer, and an electrode layer stacked sequentially.

[0058] The fabrication method of the above-mentioned flexible perovskite solar cell includes the following steps:

[0059] (a) The substrate layer (ITO glass and PEN film, with a thickness of 120 nm for ITO glass and 30 μm for PEN film) 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. Then, 80 μL of hole transport layer solution (PEDOT:PSS aqueous solution, with a concentration of 65 mg / mL for PEDOT:PSS) was dropped onto the ITO glass side of the substrate layer and spin-coated at 5000 rpm for 50 s. Then, it was annealed at 150 °C for 15 min to obtain a hole transport layer with a thickness of 40 nm.

[0060] (b) 0.6 g N-acryloyl-2-glycine, 0.1 g chitosan, 21.5 μL of N,N′-methylenebisacrylamide solution (concentration of 10 mg / mL) and 0.01 g photoinitiator 2959 were dissolved in 4 mL of deionized water to form a solution. The solution was then coated onto the hole transport layer prepared in step (a) and irradiated with 365 nm ultraviolet light for 1.5 h to obtain the composite gel layer with a thickness of 3 nm.

[0061] (c) CH3NH3I (MAI), CH(NH2)2I (FAI), CH3NH3Cl (MACl) and PbI2 were dissolved in a mixed solvent of DMSO and DMF (DMSO to DMF volume ratio 1:9), heated at 70°C and stirred continuously for 1 hour to ensure complete dissolution, yielding a perovskite precursor solution. The concentrations of FAI and PbI2 were both 1.5M (M is molar concentration, i.e., mol / L), and the concentration ratio FAI:MAI:MACl = 0.95:0.05:0.14.

[0062] The perovskite precursor solution was spin-coated onto the composite gel layer prepared in step (b) at a speed of 5000 rpm for 50 seconds. - and Pb 2+ It will penetrate into the above-mentioned composite gel layer, further forming a double cross-linked network gel. Finally, it is annealed at a temperature of 120°C for 15 minutes to crystallize and form a FA layer with a thickness of 550 nm. 0.95 MA 0.05 PbI3 perovskite layer.

[0063] (d) C is deposited on the surface of the perovskite layer obtained in step (c) by vacuum evaporation. 60 An electron transport layer is formed by evaporation at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.15 A / s and a thickness of 20 nm.

[0064] (e) A hole-blocking layer is formed by depositing a BCP on the surface of the electron transport layer obtained in step (d) using a vacuum evaporation method. The evaporation is carried out at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.2 A / s and a thickness of 8 nm.

[0065] (f) An electrode layer is prepared on the upper surface of the hole-blocking layer obtained in step (e) by physical vapor deposition (PVD). In a metal evaporation chamber, a 100 nm thick silver electrode is formed on the surface of the hole-blocking layer opposite to the perovskite light-absorbing layer using a thermal evaporation process, serving as the electrode layer; wherein the vacuum degree of the evaporation chamber is 5 × 10⁻⁶. -4 Pa, evaporation rate is 2A / s.

[0066] Example 2

[0067] This embodiment provides a flexible perovskite solar cell and its fabrication method. The flexible perovskite solar cell includes a substrate layer, a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole blocking layer, and an electrode layer stacked sequentially.

[0068] The fabrication method of the above-mentioned flexible perovskite solar cell includes the following steps:

[0069] (a) The substrate layer (ITO glass and PEN film, with a thickness of 150 nm for ITO glass and 25 μm for PEN film) 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. Then, 60 μL of hole transport layer solution (PEDOT:PSS aqueous solution, with a concentration of 65 mg / mL for PEDOT:PSS) was dropped onto the ITO glass side of the substrate layer and spin-coated at 5000 rpm for 50 s. Then, it was annealed at 150 °C for 15 min to obtain a hole transport layer with a thickness of 30 nm.

[0070] (b) 0.6 g N-acryloyl-2-glycine, 0.1 g chitosan, 7.2 μL of N,N′-methylenebisacrylamide solution (concentration of 10 mg / mL) and 0.018 g photoinitiator 2959 were dissolved in 5 mL of deionized water to form a solution. The solution was then coated onto the hole transport layer prepared in step (a) and irradiated with 365 nm ultraviolet light for 1 h to obtain the composite gel layer with a thickness of 2 nm.

[0071] (c) MAI, FAI, MACl, and PbI2 were dissolved in a mixed solvent of DMSO and DMF (volume ratio of DMSO to DMF: 1:9), heated at 70°C and stirred continuously for 1 hour to ensure complete dissolution, yielding a perovskite precursor solution. The concentrations of FAI and PbI2 were both 1.5M (M is molar concentration, i.e., mol / L), and the concentration ratio FAI:MAI:MACl = 0.95:0.05:0.14.

[0072] The perovskite precursor solution was spin-coated onto the composite gel layer prepared in step (b) at a speed of 6500 rpm for 50 seconds. - and Pb 2+ It will penetrate into the above-mentioned composite gel layer, further forming a double cross-linked network gel. Finally, it is annealed at a temperature of 120°C for 15 minutes to crystallize and form a FA layer with a thickness of 400 nm. 0.95 MA 0.05 PbI3 perovskite layer.

[0073] (d) C is deposited on the surface of the perovskite layer obtained in step (c) by vacuum evaporation. 60 An electron transport layer is formed by evaporation at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.15 A / s and a thickness of 25 nm.

[0074] (e) A hole-blocking layer is formed by depositing a BCP on the surface of the electron transport layer obtained in step (d) using a vacuum evaporation method. The evaporation is carried out at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.2 A / s and a thickness of 5 nm.

[0075] (f) An electrode layer is prepared on the upper surface of the hole-blocking layer obtained in step (e) by physical vapor deposition (PVD). In a metal evaporation chamber, a 90 nm thick silver electrode is formed on the surface of the hole-blocking layer opposite to the perovskite light-absorbing layer using a thermal evaporation process, serving as the electrode layer; wherein the vacuum degree of the evaporation chamber is 5 × 10⁻⁶. -4 Pa, evaporation rate is 2A / s.

[0076] Example 3

[0077] This embodiment provides a flexible perovskite solar cell and its fabrication method. The flexible perovskite solar cell includes a substrate layer, a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole blocking layer, and an electrode layer stacked sequentially.

[0078] The fabrication method of the above-mentioned flexible perovskite solar cell includes the following steps:

[0079] (a) The substrate layer (ITO glass and PEN film, with a thickness of 100 nm for ITO glass and 40 μm for PEN film) 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. Then, 100 μL of hole transport layer solution (PEDOT:PSS aqueous solution, with a concentration of 65 mg / mL) was dropped onto the ITO glass side of the substrate layer and spin-coated at 5000 rpm for 50 s. Then, it was annealed at 150 °C for 15 min to obtain a hole transport layer with a thickness of 50 nm.

[0080] (b) 0.6 g N-acryloyl-2-glycine, 0.1 g chitosan, 32 μL of N,N′-methylenebisacrylamide solution (concentration of 10 mg / mL) and 0.005 g photoinitiator 2959 were dissolved in 4 mL of deionized water to form a solution. The solution was then coated onto the hole transport layer prepared in step (a) and irradiated with 365 nm ultraviolet light for 2 h to obtain the composite gel layer with a thickness of 4 nm.

[0081] (c) MAI, FAI, MACl, and PbI2 were dissolved in a mixed solvent of DMSO and DMF (volume ratio of DMSO to DMF: 1:9), heated at 70°C and stirred continuously for 1 hour to ensure complete dissolution, yielding a perovskite precursor solution. The concentrations of FAI and PbI2 were both 1.5M (M is molar concentration, i.e., mol / L), and the concentration ratio FAI:MAI:MACl = 0.95:0.05:0.14.

[0082] The perovskite precursor solution was spin-coated onto the composite gel layer prepared in step (b) at a speed of 6500 rpm for 50 seconds. - and Pb 2+ It will penetrate into the above-mentioned composite gel layer, further forming a double cross-linked network gel. Finally, it is annealed at a temperature of 120°C for 15 minutes to crystallize and form a FA layer with a thickness of 400 nm. 0.95 MA 0.05 PbI3 perovskite layer.

[0083] (d) C is deposited on the surface of the perovskite layer obtained in step (c) by vacuum evaporation. 60 An electron transport layer is formed by evaporation at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.15 A / s and a thickness of 30 nm.

[0084] (e) A hole-blocking layer is formed by depositing a BCP on the surface of the electron transport layer obtained in step (d) using a vacuum evaporation method. The evaporation is carried out at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.2 A / s and a thickness of 10 nm.

[0085] (f) An electrode layer is prepared on the upper surface of the hole-blocking layer obtained in step (e) by physical vapor deposition (PVD). In a metal evaporation chamber, a silver electrode with a thickness of 80 nm is formed on the surface of the hole-blocking layer opposite to the perovskite light-absorbing layer using a thermal evaporation process, serving as the electrode layer; wherein the vacuum degree of the evaporation chamber is 5 × 10⁻⁶. -4 Pa, evaporation rate is 2A / s.

[0086] Example 4

[0087] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Example 1 is that the mass of N-acryloyl-2-glycine is adjusted to 0.4g, while the rest is the same as Example 1.

[0088] Example 5

[0089] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of N-acryloyl-2-glycine is adjusted to 0.5g, while the rest is the same as Embodiment 1.

[0090] Example 6

[0091] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of chitosan is adjusted to 0.02g, while the rest is the same as Embodiment 1.

[0092] Example 7

[0093] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of chitosan is adjusted to 0.2g, while the rest is the same as Embodiment 1.

[0094] Example 8

[0095] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of chitosan is adjusted to 0.3g, while the rest is the same as Embodiment 1.

[0096] Example 9

[0097] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of chitosan is adjusted to 0.005g, while the rest is the same as Embodiment 1.

[0098] Example 10

[0099] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of N-acryloyl-2-glycine is adjusted to 0.2g, while the rest is the same as Embodiment 1.

[0100] Example 11

[0101] This embodiment provides a flexible perovskite solar cell and its preparation method. The only difference between this embodiment and Embodiment 1 is that the mass of N-acryloyl-2-glycine is adjusted to 0.8g, while the rest is the same as Embodiment 1.

[0102] Comparative Example 1

[0103] This comparative example provides a flexible perovskite solar cell and its preparation method, which differs from Example 1 only in that it does not include a composite gel layer;

[0104] The fabrication method of flexible perovskite solar cells includes the following steps:

[0105] (a) The substrate layer (a PEN film with ITO glass, the thickness of the ITO glass is 120 nm and the thickness of the PEN film is 30 μm) was cleaned, specifically 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. Then, 80 μL of hole transport layer solution (PEDOT:PSS aqueous solution, the concentration of PEDOT:PSS is 65 mg / mL) was dropped onto the ITO glass side of the substrate layer and spin-coated at 5000 rpm for 50 s. Then, it was annealed at 150 °C for 15 min to obtain a hole transport layer with a thickness of 40 nm.

[0106] (b) MAI, FAI, MACl, and PbI2 were dissolved in a mixed solvent of DMSO and DMF (DMSO to DMF volume ratio 1:9), heated at 70°C and stirred continuously for 1 hour to ensure complete dissolution, yielding a perovskite precursor solution. The concentrations of FAI and PbI2 were both 1.5M (M is molar concentration, i.e., mol / L), and the concentration ratio FAI:MAI:MACl = 0.95:0.05:0.14.

[0107] The perovskite precursor solution was spin-coated onto the hole transport layer prepared in step (a) at 5000 rpm for 50 seconds. Finally, it was annealed at 120°C for 15 minutes to crystallize and form a FA layer with a thickness of 550 nm. 0.95 MA 0.05 PbI3 perovskite layer.

[0108] (c) C is deposited on the surface of the perovskite layer obtained in step (b) by vacuum evaporation. 60 An electron transport layer is formed by evaporation at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.15 A / s and a thickness of 20 nm.

[0109] (d) A hole-blocking layer is formed by depositing a BCP on the surface of the electron transport layer obtained in step (c) using a vacuum evaporation method. The evaporation is carried out at a vacuum degree of 5 × 10⁻⁶. -4 The evaporation was carried out under Pa conditions at a rate of 0.2 A / s and a thickness of 8 nm.

[0110] (e) An electrode layer is prepared on the upper surface of the hole-blocking layer obtained in step (d) by physical vapor deposition (PVD). In a metal evaporation chamber, a 100 nm thick silver electrode is formed on the surface of the hole-blocking layer opposite to the perovskite light-absorbing layer using a thermal evaporation process, serving as the electrode layer; wherein the vacuum degree of the evaporation chamber is 5 × 10⁻⁶. -4Pa, evaporation rate is 2A / s.

[0111] Comparative Example 2

[0112] This comparative example provides a flexible perovskite solar cell and its preparation method. The difference between this example and Example 1 is that N-acryloyl-2-glycine is replaced with an amount of acrylamide, while the rest is the same as in Example 1.

[0113] Comparative Example 3

[0114] This comparative example provides a flexible perovskite solar cell and its preparation method. The difference between this example and Example 1 is that 0.6g of N-acryloyl-2-glycine and 0.1g of chitosan are replaced with 0.7g of N-acryloyl-2-glycine, and chitosan is not added. Otherwise, it is the same as Example 1.

[0115] The photoelectric conversion efficiency performance of the flexible perovskite solar cells provided in the above embodiments and comparative examples was tested. Measurements were performed using a solar energy simulation test system. The light source of the solar energy simulation test system used a 500W xenon lamp solar spectrum simulator, and the light source was calibrated using a standard silicon cell KG-5. The system was tested under a solar intensity (AM 1.5G: 100mW / cm²). 2 Measurements were performed under the following conditions. By applying a continuously varying voltage (-0.5V to 1.2V) across the flexible perovskite solar cell, the output current of the flexible perovskite solar cell was measured (using a Keithley 2400 tester). The product of the two measurements yielded the JV test curve, which shows the photoelectric conversion efficiency of the flexible perovskite solar cell under different conditions.

[0116] (1) Open circuit voltage (V) oc The maximum voltage applied across the flexible perovskite solar cell after irradiation by the solar energy simulation test system is the open-circuit voltage (V). oc The test was conducted using a Keithley 2400.

[0117] (2) Short-circuit current (J) sc The current at which the potential difference between the positive and negative electrodes of a flexible perovskite solar cell is zero was measured using a Keithley 2400.

[0118] (3) Fill factor (FF): FF = (I max ×V max ) / (Jsc×Voc)×100, where, I max and V max These are the current and voltage values ​​of a flexible perovskite solar cell at its maximum power point.

[0119] (4) Photovoltaic conversion efficiency (PCE): PCE = (Jsc ×V oc ×FF) / P in ×100; where, P in The incident power of the solar energy simulation test system.

[0120] (5) Stability test: The photoelectric conversion efficiency of the unencapsulated flexible perovskite solar cell was tested after 1000 hours of operation in a glove box.

[0121] (6) Flexibility test: The photoelectric conversion efficiency of the unencapsulated flexible perovskite solar cell was tested in a glove box after being bent 3000 times with a bending radius of 5mm.

[0122] The test results for open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency are shown in Table 1 below. The stability and flexibility test results are as follows: Figure 6 and Figure 7 .

[0123] Table 1

[0124]

[0125]

[0126] As shown in Table 1, the flexible perovskite solar cell prepared by using a composite gel of poly(N-acryloyl-2-glycine) and chitosan as a composite gel layer to connect with the perovskite layer in this invention has good flexibility, high photoelectric conversion efficiency, and good stability.

[0127] In this invention, the composite gel of poly(N-acryloyl-2-glycine) and chitosan not only possesses excellent mechanical properties, reducing the Young's modulus of the perovskite layer and improving the flexibility of flexible perovskite solar cells; but also, the carboxyl groups in the composite gel layer interact with the I group in the perovskite material through hydrogen bonds. - Combination (e.g.) Figure 1 This effectively suppresses ion migration and enhances the stability of flexible perovskite solar cells; simultaneously, the carboxylate ions in the composite gel layer can interact with Pb through strong electrostatic forces. 2+ Combined, capturing Pb 2+ (like Figure 2 This effectively suppresses Pb leakage after deformation and damage to flexible perovskite solar cells; in addition, the amide groups and carboxyl groups contained in the composite gel layer can effectively passivate defects in the perovskite, significantly improving the photoelectric conversion efficiency of the device.

[0128] from Figure 3It can be seen that the XRD diffraction peak positions of the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 are the same, and there are no other impurity peaks, indicating that the composite gel layer does not affect the perovskite lattice. Furthermore, the relative height of the PbI2 diffraction peak in the perovskite layer is significantly reduced after adding the composite gel layer, further indicating that the amide and carboxyl groups contained in the composite gel layer can effectively passivate defects in the perovskite and significantly improve the light conversion efficiency of the device.

[0129] Figure 4 and Figure 5 Characterization of the optical properties of the perovskite layers provided in Example 1 and Comparative Example 1, from Figure 4 The ultraviolet spectrum shows that the FA after adding the composite gel layer 0.95 MA 0.05 The absorption peak of the PbI3 perovskite layer shows a slight red shift, mainly because the composite gel effectively promotes the crystallization of the perovskite layer, resulting in a larger final perovskite size. Simultaneously, the addition of the composite gel layer improves the FA... 0.95 MA 0.05 Fluorescence spectra of PbI3 perovskite layers (e.g.) Figure 5 The results showed a significant improvement, further indicating that the amide and carboxyl groups contained in the composite gel layer can effectively passivate defects in perovskites and reduce non-radiative recombination.

[0130] from Figure 6 It can be seen that the stability of the flexible perovskite solar cell with the added composite gel layer (Example 1) can still maintain about 90% of the initial value after 1000 hours, while the flexible perovskite solar cell without the added composite gel layer (Comparative Example 1) has a faster degradation rate. This is mainly because the composite gel layer can react with Pb in the perovskite. 2+ and I - The tight bonding effectively suppresses ion migration and enhances the stability of flexible perovskite solar cells.

[0131] from Figure 7 It can be seen that the mechanical properties of the flexible perovskite solar cell (Example 1) after adding the composite gel layer are significantly improved. This is because the double cross-linked network structure in the composite gel layer not only has excellent mechanical properties, but also can interact with Pb in the perovskite. 2+ and I - By tightly bonding the layers together, the Young's modulus of the perovskite layer is reduced, thus improving the flexibility of flexible perovskite solar cells. All of these measures effectively enhance the mechanical properties of flexible perovskite solar cells.

[0132] The flexible perovskite solar cells provided in Example 1 and Comparative Example 1 were immersed in the same mass of water for 8 hours, and the lead concentration in the aqueous solution was tested. Figure 6It can be seen that the Pb in the aqueous solution formed by immersing the flexible perovskite solar cell provided in Comparative Example 1 is... 2+ The concentration of Pb was 0.3789 ppm. (Example 1: Flexible perovskite solar cell with composite gel layer in aqueous solution) 2+ The concentration was 0.1356 ppm, further demonstrating that the carboxylate ions in the composite gel layer can interact with Pb through strong electrostatic forces. 2+ Combined, thereby capturing Pb 2+ This effectively suppresses Pb leakage after solar cell damage.

[0133] Compared with Example 1, if the mass fraction of chitosan in the solution is too large (Example 8), it will inhibit the transport of charge carriers, thereby affecting the photoelectric conversion efficiency. If the mass fraction of chitosan in the solution is too small (Example 9), when the halogen anion induces the salting out of the polymer, the number of chitosan chains that spontaneously collapse will decrease, and the number of chain entanglement networks formed will decrease, resulting in poor bending performance of the flexible perovskite solar cell. At the same time, the number of passivation groups contained in chitosan will also affect the photoelectric conversion efficiency. Therefore, it can be seen that the flexible perovskite solar cell prepared with the mass fraction of chitosan in the solution within a specific range has better performance.

[0134] Compared with Example 1, if the mass fraction of N-acryloyl-2-glycine in the solution is too small (Example 8), the photoelectric conversion efficiency, stability, and flexibility all decrease; if the mass fraction of N-acryloyl-2-glycine in the solution is too large (Example 9), the photoelectric conversion efficiency, stability, and flexibility all decrease. Therefore, it can be seen that the flexible perovskite solar cell prepared with the mass fraction of N-acryloyl-2-glycine in the solution within a specific range has better performance.

[0135] A comparison of Example 1 and Comparative Example 1 shows that the flexible perovskite solar cell prepared with the addition of the composite gel layer exhibits significant improvements in open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency. This is because the amide and carboxyl groups contained in the composite gel layer effectively passivate defects in the perovskite, significantly improving the performance of the flexible perovskite solar cell.

[0136] A comparison of Example 1 and Comparative Example 2 shows that if N-acryloyl-2-glycine is replaced with the same amount of acrylamide, the photoelectric conversion efficiency, stability, and flexibility all decrease. This is because the -COOH group in N-acryloyl-2-glycine can passivate Pb. 2+ A drawback is that if the polymer chain contains only amide groups, the passivation effect on the perovskite layer surface is relatively poor.

[0137] A comparison of Example 1 and Comparative Example 3 shows that without the addition of chitosan, the photoelectric conversion efficiency, stability, and flexibility all decrease. This is because without chitosan, when the halogen anions induce the salting out of the polymer, no chitosan chains spontaneously collapse, thus only a single-layer network structure of polyN-acryloyl-2-glycine is formed, resulting in poor bending performance of the flexible perovskite solar cell. At the same time, the lack of passivation groups contained in chitosan also affects the photoelectric conversion efficiency.

[0138] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A flexible perovskite solar cell, characterized in that, The flexible perovskite solar cell comprises a substrate layer, a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole blocking layer, and an electrode layer stacked sequentially. The composite gel layer comprises a composite gel of poly(N-acryloyl-2-glycine) and chitosan.

2. The flexible perovskite solar cell according to claim 1, characterized in that, The substrate layer includes ITO glass and a flexible substrate; Preferably, the flexible substrate comprises any one of polyethylene terephthalate film, polyethylene naphthalate film, or colorless polyimide film.

3. The flexible perovskite solar cell according to claim 1 or 2, characterized in that, The hole transport layer comprises p-type inorganic semiconductor materials and / or p-type organic semiconductor materials; Preferably, the p-type inorganic semiconductor material includes any one or a combination of at least two of copper sulfide, nickel oxide, molybdenum oxide, cuprous iodide, or cuprous thiocyanate; Preferably, the p-type organic semiconductor material includes any one or a combination of at least two of the following: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, 4-butyl-N,N-diphenylaniline homopolymer, polyvinylcarbazole, [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [3-(9H-carbazole-9-yl)ethyl]phosphonic acid, or [4-(9H-carbazole-9-yl)ethyl]phosphonic acid.

4. The flexible perovskite solar cell according to any one of claims 1-3, characterized in that, The perovskite layer comprises perovskite material; Preferably, the perovskite material is ABX3, wherein A is CH3NH3. + CH(NH2)2 + Cs + or Rb + B is any combination of one or at least two of the following, where B is Pb. 2+ Sn 2+ Or Ge 2+ Any combination of one or at least two of them, X is Cl - ,Br - Or I - Any one or at least two of them.

5. The flexible perovskite solar cell according to any one of claims 1-4, characterized in that, The electron transport layer comprises n-type inorganic semiconductor materials and / or n-type organic semiconductor materials; Preferably, the n-type inorganic semiconductor material includes any one or a combination of at least two of TiO2, SnO2, ZnO, or ZnO-ZnS; Preferably, the n-type organic semiconductor material includes C 60 and / or [6,6]-phenyl-C 61 methyl butyrate; Preferably, the hole-blocking layer comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; Preferably, the electrode layer comprises any one of Au, Ag, Al, or low-temperature carbon.

6. The flexible perovskite solar cell according to any one of claims 2-5, characterized in that, The thickness of the flexible substrate is 2-50 μm; Preferably, the thickness of the ITO glass is 100-150 nm; Preferably, the thickness of the hole transport layer is 10-300 nm; Preferably, the thickness of the composite gel layer is 1-5 nm; Preferably, the thickness of the perovskite layer is 400-700 nm; Preferably, the thickness of the electron transport layer is 10-50 nm; Preferably, the thickness of the hole-blocking layer is 3-15 nm; Preferably, the thickness of the electrode layer is 80-100 nm.

7. A method for fabricating a flexible perovskite solar cell as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: sequentially preparing a hole transport layer, a composite gel layer, a perovskite layer, an electron transport layer, a hole blocking layer, and an electrode layer on a substrate layer to obtain the flexible perovskite solar cell.

8. The preparation method according to claim 7, characterized in that, The specific preparation method of the composite gel layer and perovskite layer includes the following steps: (1) N-acryloyl-2-glycine, chitosan, crosslinking agent, photoinitiator and water are mixed to form a solution, which is then coated onto the hole transport layer and irradiated with ultraviolet light to obtain the composite gel layer. (2) Mix the perovskite material and solvent, coat it onto the composite gel layer obtained in step (1), and heat it to obtain the perovskite layer; Preferably, the crosslinking agent comprises N,N′-methylenebisacrylamide.

9. The preparation method according to claim 8, characterized in that, The solution in step (1) comprises the following components by mass: 0.4-0.6 parts of N-acryloyl-2-glycine, 0.02-0.2 parts of chitosan, and 3-5 parts of water; Preferably, the molar amount of the crosslinking agent accounts for 0.01%-0.05% of the molar amount of N-acryloyl-2-glycine; Preferably, the molar amount of the photoinitiator accounts for 0.5%-2% of the molar amount of N-acryloyl-2-glycine; Preferably, the wavelength of the ultraviolet light irradiation is 300-380nm, and the irradiation time is 1-2h.

10. The preparation method according to any one of claims 7-9, characterized in that, The solvent in step (2) includes any one or a combination of at least two of N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolinone, dimethylacetamide, N,N-dimethylpropenylurea, acetonitrile or 2-mercaptoethanol.

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