Flexible perovskite solar cell and preparation method and application thereof

Abstract

The invention provides a flexible perovskite solar cell and a preparation method thereof. The flexible perovskite solar cell comprises a substrate, an electron transport layer, a hydrogel layer, a perovskite light absorption layer, a hole transport layer and an electrode which are arranged in sequence. And the material of the hydrogel layer comprises cross-linked polyacrylamide-carrageenan gel. According to the flexible perovskite solar cell, the hydrogel layer is arranged between the electron transmission layer and the perovskite light absorption layer, so that the flexible perovskite solar cell has excellent bending resistance, high energy conversion efficiency, good stability and long service life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar cells, and particularly relates to a flexible perovskite solar cell and a preparation method and application thereof. BACKGROUND

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

[0003] The biggest feature of perovskite solar cells is bendability and recoverability. Traditional recoverability refers to the deformation of a material under external force and the ability of an object to recover from deformation after the external force is removed. The recoverability of an object is related to the characteristics of the material itself. Therefore, to obtain high recoverability of FPSCs, there are some requirements for chemical composition and preparation method. The composition of FPSCs includes a flexible substrate, electrodes, a perovskite light-absorbing material, and a charge transport material.

[0004] The film formation quality of the perovskite light-absorbing material determines the quality of the FPSC. Unlike rigid perovskite solar cells, FPSCs need to be repeatedly stretched and bent, so FPSCs need to have elastic ability. The polycrystalline structure of perovskite material makes it easy to be brittle, and the grain boundaries are easily damaged. Especially during bending, cracks of different degrees will occur in the perovskite layer, and these cracks will produce free electron-hole recombination centers. The higher the density of electron-hole recombination centers, the lower the carrier lifetime, which further reduces the efficiency and stability of the device.

[0005] Therefore, it is an urgent problem in the field to develop a flexible perovskite solar cell with good bending resistance, good recoverability, and high energy conversion efficiency. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a flexible perovskite solar cell and a preparation method and application thereof. The flexible perovskite solar cell has excellent bending resistance and high energy conversion efficiency, good stability, and long service life.

[0007] To achieve this purpose, the technical scheme adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a flexible perovskite solar cell, which comprises, in sequence, a substrate, an electron transport layer, a hydrogel layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode; the material of the hydrogel layer comprises cross-linked polyacrylamide-carrageenan gel.

[0009] In this invention, the cross-linked polyacrylamide-carrageenan gel possesses a flexible structure due to the cross-linked polyacrylamide (PAAm) network, preventing structural breakage caused by further bending. Furthermore, the amide groups effectively passivate defects in the perovskite layer, improving the conversion efficiency of the perovskite solar cell. The carrageenan element imparts conductivity to the gel, enhancing the energy conversion efficiency of the flexible perovskite solar cell. In addition, the metal ions in the perovskite light-absorbing layer can coordinate with the sulfate groups of carrageenan to form a physically cross-linked structure, effectively suppressing ion migration, reducing metal leakage in the perovskite light-absorbing layer, passivating surface defects, and reducing non-radiative recombination, further improving the energy conversion efficiency of the flexible perovskite solar cell. By placing the hydrogel layer between the electron transport layer and the perovskite light-absorbing layer, the flexible perovskite solar cell exhibits excellent bending resistance, high energy conversion efficiency, good stability, and a long service life.

[0010] Preferably, the thickness of the hydrogel layer is 2 to 5 nm, for example, it can be 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, 3 nm, 3.2 nm, 3.4 nm, 3.6 nm, 3.8 nm, 4 nm, 4.2 nm, 4.4 nm, 4.6 nm, 4.8 nm, 5 nm, etc.

[0011] In this invention, the thickness of the hydrogel layer is in the range of 2 to 5 nm, and the flexible perovskite solar cell has both high conversion efficiency and bending resistance; when the thickness is less than 2 nm, the conversion efficiency decreases and the bending resistance deteriorates; when the thickness is greater than 5 nm, the conversion efficiency decreases.

[0012] Preferably, the raw materials for preparing the crosslinked polyacrylamide-carrageenan gel include acrylamide monomers, crosslinking agents, initiators, and carrageenan.

[0013] Preferably, the mass ratio of the acrylamide monomer to carrageenan is 1:(0.5-2), wherein the specific values ​​of (0.5-2) can be, for example, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

[0014] Preferably, the acrylamide monomer includes acrylamide (AAm).

[0015] Preferably, the carrageenan includes K-carrageenan.

[0016] Preferably, the mass ratio of the crosslinking agent to the acrylamide monomer is (0.0005~0.003):1, wherein the specific values ​​of (0.0005~0.003) can be, for example, 0.0005, 0.0008, 0.001, 0.0012, 0.0015, 0.0018, 0.002, 0.0022, 0.0025, 0.0028, 0.003, etc.

[0017] Preferably, the crosslinking agent comprises N,N'-methylenebisacrylamide (MBAA).

[0018] Preferably, the mass ratio of the initiator to the acrylamide monomer is (0.005-0.02):1, wherein the specific values ​​of (0.005-0.02) can be, for example, 0.005, 0.006, 0.008, 0.01, 0.012, 0.014, 0.016, 0.018, 0.02, etc.

[0019] Preferably, the initiator comprises at least one of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenylacetone, 1-hydroxycyclohexylbenzophenone, benzophenone, or 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0020] In this invention, the initiator is not limited to the initiators listed above; any photoinitiator commonly used in the art that can be used to initiate polymerization reactions is acceptable.

[0021] Preferably, the perovskite light-absorbing layer has the general structural formula ABX3; wherein A is selected from CH3NH3. + CH(NH2)2 + Cs + or Rb + B is any one or at least two of the following; B is selected from Sn. 2+ Pb 2+ Or Ge 2+ X is any one or at least two of the following, where X is selected from Cl. - ,Br - Or I - Any one or at least two of them.

[0022] Preferably, the thickness of the perovskite light-absorbing layer is 300-700 nm, for example, it can be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, etc.

[0023] Preferably, the material of the electron transport layer includes any one or a combination of at least two of fullerenes and their derivatives (PCBM), titanium dioxide, tin dioxide, zinc oxide, or zinc oxide doped with zinc sulfide (ZnO-ZnS).

[0024] In this invention, the fullerene includes, but is not limited to, C 60 C 70 C 76 C 80 wait.

[0025] In this invention, the electron transport layer is an n-type inorganic semiconductor or an n-type organic semiconductor.

[0026] Preferably, the thickness of the electron transport layer is 15-45 nm, for example, it can be 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 45 nm, etc.

[0027] Preferably, the material of the hole transport layer 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), [4-(9H-carbazole-9-yl)ethyl]phosphonic acid (4PACz), nickel oxide, cuprous iodide, or cuprous thiocyanate.

[0028] Preferably, the thickness of the hole transport layer is 10–300 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, etc.

[0029] Preferably, the substrate comprises a flexible substrate and a conductive layer disposed sequentially, wherein the conductive layer is stacked with an electron transport layer.

[0030] Preferably, the conductive layer comprises any one of indium tin oxide (ITO), fluorine-doped SnO2 (FTO), or aluminum-doped ZnO (AZO).

[0031] In this invention, the flexible substrate is made of at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or colorless polyimide (CPI).

[0032] Preferably, the thickness of the flexible substrate is 1–4 μm, for example, it can be 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4 μm, etc.

[0033] Preferably, the thickness of the conductive layer is 100-150 nm, for example, it can be 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, etc.

[0034] Preferably, the electrode comprises a metal electrode and / or a carbon electrode.

[0035] Preferably, the metal electrode includes at least one of an aluminum electrode, a gold electrode, a silver electrode, or a copper electrode.

[0036] Preferably, the thickness of the metal electrode is 40-150 nm, for example, it can be 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, etc.

[0037] Preferably, the carbon electrode comprises a low-temperature carbon electrode.

[0038] Preferably, the thickness of the carbon electrode is 5 to 25 μm, for example, it can be 5 μm, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, etc.

[0039] In a second aspect, the present invention provides a method for fabricating a flexible perovskite solar cell according to the first aspect, the method comprising the following steps:

[0040] The flexible perovskite solar cell is obtained by sequentially stacking a substrate, an electron transport layer, a hydrogel layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode.

[0041] In this invention, the substrate further includes a washing step before use; the washing includes ultrasonically cleaning the substrate sequentially with detergent, deionized water, acetone and anhydrous ethanol, and then drying it with a nitrogen gun; wherein the ultrasonic cleaning power is 50-150Hz and the ultrasonic cleaning time is 10-20min.

[0042] The method for preparing the electron transport layer described in this invention can employ conventional methods in the prior art, including but not limited to the following: coating the substrate surface with an electron transport layer material, annealing, and obtaining the electron transport layer; the coating rotation speed is 3000–5000 rpm, for example, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, etc.; the coating time is 20–40 s, for example, 20 s, 25 s, 30 s, 35 s, 40 s, etc.; the annealing temperature is 100–200℃, for example, 100℃, 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, etc.; the annealing time is 20–40 min, for example, 20 min, 25 min, 30 min, 35 min, 40 min, etc.

[0043] Preferably, the surface of the electron transport layer is coated with cross-linked polyacrylamide-carrageenan gel and annealed to obtain the hydrogel layer.

[0044] Preferably, the preparation method of the crosslinked polyacrylamide-carrageenan gel includes: mixing acrylamide monomers, crosslinking agents, initiators and carrageenan, and irradiating with ultraviolet light to obtain the crosslinked polyacrylamide-carrageenan gel.

[0045] In this invention, the mixing process includes: first mixing acrylamide monomers, crosslinking agents, initiators, and solvents (including water) to obtain solution A; then mixing carrageenan with solvents (including water) at 60–100°C to obtain solution B; and finally cooling to room temperature and mixing solution B with solution A.

[0046] Preferably, the intensity of the ultraviolet irradiation is 100–300 mW / cm². 2 For example, it can be 100mW / cm 2 120mW / cm 2 150mW / cm 2 180mW / cm 2 200mW / cm 2 220mW / cm 2 250mW / cm 2 280mW / cm 2 300mW / cm 2etc.; the time is 1 to 2 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, etc.

[0047] In this invention, the wavelength of the ultraviolet light is 365nm.

[0048] In this invention, before coating the crosslinked polyacrylamide-carrageenan gel, the step of mixing the crosslinked polyacrylamide-carrageenan gel with a solvent is included. The volume ratio of the crosslinked polyacrylamide-carrageenan gel to the solvent is 1:(10-50), and the specific values ​​of (10-50) can be, for example, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, etc.

[0049] Preferably, the coating rotation speed is 2000-4000 rpm, for example, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, etc.; the time is 30-60 s, for example, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, 60 s, etc.

[0050] Preferably, the annealing temperature is 100-200℃, for example, 100℃, 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, etc.; the time is 10-40min, for example, 10min, 15min, 20min, 25min, 30min, 35min, 40min, etc.

[0051] The perovskite light-absorbing layer described in this invention can be prepared using conventional methods in the prior art, including but not limited to the following methods: coating the surface of the hydrogel layer with a perovskite precursor solution, annealing, to obtain the perovskite light-absorbing layer; the coating rotation speed is 4000-6000 rpm, for example, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm, etc.; the coating time is 20-80 s, for example, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, etc.; the annealing temperature is 100-150℃, for example, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, etc.; the annealing time is 5-20 min, for example, 5 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, etc.

[0052] In this invention, the solvent of the perovskite precursor solution includes, but is not limited to, one or more 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).

[0053] In this invention, the hole transport layer can be prepared using conventional methods in the prior art, including but not limited to the following methods: coating the surface of the perovskite light-absorbing layer with a hole transport layer material to obtain the hole transport layer; the coating rotation speed is 2000-4000 rpm, for example, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, etc.; the coating time is 20-40 s, for example, 20 s, 25 s, 30 s, 35 s, 40 s, etc.

[0054] In this invention, the electrode is prepared using conventional methods found in the prior art, including but not limited to the following: depositing electrode material on the surface of the hole transport layer to obtain the electrode; the deposition method includes vapor deposition; the vapor deposition rate is... For example, it can be... wait.

[0055] Thirdly, the present invention provides a flexible electronic product, the flexible electronic product comprising the flexible perovskite solar cell according to the first aspect.

[0056] 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.

[0057] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0058] The flexible perovskite solar cell provided by this invention provides a hydrogel layer between the electron transport layer and the perovskite light-absorbing layer. The hydrogel layer is made of cross-linked polyacrylamide-carrageenan gel, which can passivate the surface defects of the perovskite light-absorbing layer, improve the bending resistance of the perovskite light-absorbing layer, and greatly improve the bending performance and energy conversion efficiency of the flexible perovskite solar cell. This results in a flexible perovskite solar cell with good stability and long service life. Attached Figure Description

[0059] Figure 1The X-ray diffraction patterns of the perovskite light-absorbing layer of the flexible perovskite solar cell provided in Embodiment 1 and Comparative Example 1 of the present invention;

[0060] Figure 2 The ultraviolet absorption spectra of the perovskite light-absorbing layer of the flexible perovskite solar cell provided in Embodiment 1 and Comparative Example 1 of the present invention;

[0061] Figure 3 The fluorescence spectra of the perovskite light-absorbing layer of the flexible perovskite solar cell provided in Embodiment 1 and Comparative Example 1 of the present invention;

[0062] Figure 4 The graph shows the stability test data of the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 of this invention.

[0063] Figure 5 The graph shows the bending performance test data of the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 of this invention.

[0064] Figure 6 The graph shows the change in lead concentration in the aqueous solution after the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 of this invention have been immersed in the aqueous solution for 8 hours.

[0065] Figure 7 This is a schematic diagram illustrating the interaction between the hydrogel layer and the perovskite light-absorbing layer of the present invention.

[0066] Figure 8 This is a schematic diagram of the structure of the flexible perovskite solar cell provided in Embodiment 1 of the present invention;

[0067] Wherein, 1-substrate; 2-electron transport layer; 3-hydrogel layer; 4-perovskite light-absorbing layer; 5-hole transport layer; 6-electrode. Detailed Implementation

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

[0069] All materials used in this invention are commercially available or prepared using conventional methods in the art. Unless otherwise specified, the materials used in this invention are as follows:

[0070] Perovskite precursor: MAI (methylammonium iodide), FAI (formamidinium hydroiodate), MACl (methylammonium chloride), and PbI2 were dissolved in a mixed solvent of DMSO and DMF (volume ratio DMSO:DMF = 1:9). The solution was heated at 70°C and continuously stirred for 1 hour to ensure complete dissolution, yielding the perovskite precursor solution. The concentration ratio of FAI:MAI:MACl was 0.95:0.05:0.14, and the concentrations of both FAI and PbI2 were 1.5M (M is the molar concentration, i.e., mol / L).

[0071] Preparation Example 1

[0072] This preparation provides a crosslinked polyacrylamide-carrageenan gel. The raw materials for preparing the crosslinked polyacrylamide-carrageenan gel include acrylamide, N,N'-methylenebisacrylamide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator 2959), and K-carrageenan; wherein, the mass ratio of N,N'-methylenebisacrylamide to acrylamide is 0.002:1, the mass ratio of photoinitiator 2959 to acrylamide is 0.01:1, and the mass ratio of acrylamide to carrageenan is 1:1; the preparation method of the crosslinked polyacrylamide-carrageenan gel includes the following steps:

[0073] According to the formulation, acrylamide, N,N'-methylenebisacrylamide, photoinitiator 2959, and water were mixed to obtain solution A; then, K-carrageenan was mixed with water at 80°C to obtain solution B; after cooling to room temperature, solution B was mixed with solution A, and then transferred to a transparent template. Photocrosslinking polymerization was carried out in the sealed transparent template under ultraviolet (UV) irradiation, wherein the UV wavelength was 365 nm and the intensity was 200 mW / cm². 2 Irradiation time: 1.5 hours.

[0074] Preparation Example 2

[0075] This preparation provides a crosslinked polyacrylamide-carrageenan gel. The raw materials for preparing the crosslinked polyacrylamide-carrageenan gel include acrylamide, N,N'-methylenebisacrylamide, photoinitiator 2959, and K-carrageenan; wherein the mass ratio of N,N'-methylenebisacrylamide to acrylamide is 0.0025:1, the mass ratio of photoinitiator 2959 to acrylamide is 0.015:1, and the mass ratio of acrylamide to carrageenan is 1:2; the preparation method of the crosslinked polyacrylamide-carrageenan gel is the same as that in Preparation Example 1.

[0076] Preparation Example 3

[0077] This preparation provides a crosslinked polyacrylamide-carrageenan gel. The raw materials for preparing the crosslinked polyacrylamide-carrageenan gel include acrylamide, N,N'-methylenebisacrylamide, photoinitiator 2959, and K-carrageenan; wherein the mass ratio of N,N'-methylenebisacrylamide to acrylamide is 0.001:1, the mass ratio of photoinitiator 2959 to acrylamide is 0.01:1, and the mass ratio of acrylamide to carrageenan is 1:0.5; the preparation method of the crosslinked polyacrylamide-carrageenan gel is the same as that in Preparation Example 1.

[0078] Preparation Example 4

[0079] This preparation example provides a crosslinked polyacrylamide-carrageenan gel, which differs from Preparation Example 1 only in that the mass of K-carrageenan is reduced so that its mass ratio with acrylamide is 0.3:1. Other raw materials, amounts, and preparation methods are the same as in Preparation Example 1.

[0080] Preparation Example 5

[0081] This preparation example provides a crosslinked polyacrylamide-carrageenan gel, which differs from Preparation Example 1 only in that the mass of K-carrageenan is increased so that its mass ratio with acrylamide is 2.2:1. Other raw materials, amounts, and preparation methods are the same as in Preparation Example 1.

[0082] Comparative Preparation Example 1

[0083] This comparative preparation example provides a cross-linked polyacrylamide gel, which differs from Preparation Example 1 only in that the raw materials used in this preparation do not include K-carrageenan; the other raw materials, amounts, and preparation methods are the same as in Preparation Example 1.

[0084] Example 1

[0085] This embodiment provides a flexible perovskite solar cell, the structural schematic of which is shown below. Figure 8 As shown, the flexible perovskite solar cell comprises, in sequence, a substrate 1, an electron transport layer 2, a hydrogel layer 3 (crosslinked polyacrylamide-carrageenan gel provided in Preparation Example 1), a perovskite light-absorbing layer 4, a hole transport layer 5, and an electrode 6; the fabrication method of the flexible perovskite solar cell includes the following steps:

[0086] (1) The PEN / ITO substrate was ultrasonically cleaned in sequence with detergent, deionized water, acetone and anhydrous ethanol, and then dried with a nitrogen gun for later use; the ultrasonic cleaning power was 100 Hz and the ultrasonic cleaning time was 15 min.

[0087] (2) Under air conditions, at a rotation speed of 4000 rpm, SnO2 nanocolloid solution (concentration of about 3.67%) was spin-coated onto the surface of ITO conductive glass for 30 s. Then, it was annealed on a hot plate at 150 °C for 30 min to obtain an electron transport layer with a thickness of 25 nm.

[0088] (3) Mix 0.1 mL of cross-linked polyacrylamide-carrageenan gel with 3 mL of water (volume ratio of 1:30), and then spin coat the resulting solution onto the surface of the electron transport layer obtained in step (2). The spin coating speed is 3000 rpm and the time is 45 s. Then anneal at 130 °C for 25 min to obtain a hydrogel layer with a thickness of 3 nm.

[0089] (4) The perovskite precursor solution was spin-coated onto the surface of the hydrogel layer obtained in step (3) at a speed of 5000 rpm for 50 s, and then annealed at 120 °C for 15 min to obtain FA with a thickness of 550 nm. 0.95 MA 0.05 PbI3 perovskite light-absorbing layer.

[0090] (5) The preparation method of the doped Spiro-OMeTAD solution is as follows: First, prepare a lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (concentration of 520 mg / mL, solvent of acetonitrile), then measure 72.3 mg Spiro-OMeTAD powder, 28.8 μL of tributyl phosphate (tbp) solution and 17.5 μL of the Li-TFSI solution and dissolve them in 1 mL of chlorobenzene. After stirring, 1 mL of Spiro-OMeTAD solution is obtained. Then, in a glove box, the Spiro-OMeTAD solution is spin-coated on the surface of the perovskite light-absorbing layer obtained in step (4). The spin-coating speed is 3000 rpm and the time is 30 s to obtain a hole transport layer with a thickness of 200 nm.

[0091] (6) Gold is deposited on the surface of the hole transport layer obtained in step (5), and the vacuum degree in the evaporation chamber is 1.0 × 10⁻⁶. -4 Pa; evaporation rate is A metal electrode with a thickness of 80 nm is obtained, thus obtaining the flexible perovskite solar cell.

[0092] Example 2

[0093] This embodiment provides a flexible perovskite solar cell, which differs from Example 1 only in that the material of the hydrogel layer is the cross-linked polyacrylamide-carrageenan gel provided in Preparation Example 2, and the thickness of the hydrogel layer is 5 nm; in the preparation method, 3 mL of water is replaced with 1 mL of water in step (3), and the other raw materials, amounts, structures and preparation methods are the same as in Example 1.

[0094] Example 3

[0095] This embodiment provides a flexible perovskite solar cell, which differs from Example 1 only in that the material of the hydrogel layer is the cross-linked polyacrylamide-carrageenan gel provided in Preparation Example 3, and the thickness of the hydrogel layer is 2 nm; in the preparation method, 3 mL of water is replaced with 5 mL of water in step (3), and the other raw materials, amounts, structures and preparation methods are the same as in Example 1.

[0096] Example 4

[0097] This embodiment provides a flexible perovskite solar cell, which differs from Embodiment 1 only in that the thickness of the hydrogel layer is 6 nm; in the preparation method, 3 mL of water is replaced with 0.5 mL of water in step (3), and the other raw materials, amounts, structures and preparation methods are the same as in Embodiment 1.

[0098] Example 5

[0099] This embodiment provides a flexible perovskite solar cell, which differs from Embodiment 1 only in that the thickness of the hydrogel layer is 1 nm; in the preparation method, 3 mL of water is replaced with 5.5 mL of water in step (3), and the other raw materials, amounts, structures and preparation methods are the same as in Embodiment 1.

[0100] Example 6

[0101] This embodiment provides a flexible perovskite solar cell, which differs from Example 1 only in that the hydrogel layer is made of cross-linked polyacrylamide-carrageenan gel provided in Preparation Example 4. Other raw materials, amounts, structures, and preparation methods are the same as in Example 1.

[0102] Example 7

[0103] This embodiment provides a flexible perovskite solar cell, which differs from Example 1 only in that the hydrogel layer is made of cross-linked polyacrylamide-carrageenan gel provided in Preparation Example 5. Other raw materials, amounts, structures, and preparation methods are the same as in Example 1.

[0104] Comparative Example 1

[0105] This comparative example provides a flexible perovskite solar cell, which differs from Example 1 only in that the flexible perovskite solar cell does not have a hydrogel layer, and step (3) is not performed in the preparation method. Other raw materials, amounts, structures and preparation methods are the same as in Example 1.

[0106] Comparative Example 2

[0107] This comparative example provides a flexible perovskite solar cell, which differs from Example 1 only in that the hydrogel layer is made of cross-linked polyacrylamide gel provided in Comparative Preparation Example 1. Other raw materials, amounts, structures, and preparation methods are the same as in Example 1.

[0108] Performance testing

[0109] (1) The X-ray diffraction (XRD) patterns of the perovskite absorbing layers obtained in Example 1 and Comparative Example 1 were tested, and the results are as follows: Figure 1 As shown; by Figure 1 It can be seen that the XRD diffraction peak positions of the perovskite light-absorbing layer with and without gel treatment are the same, and there are no extra impurity peaks, indicating that the gel does not affect the perovskite lattice. Furthermore, the relative height of the PbI2 diffraction peak in the perovskite film is significantly reduced after gel treatment. This is because the amide groups contained in the gel can effectively passivate defects in the perovskite, reducing Pb... 2+ It can coordinate with the sulfate groups of K-carrageenan, reducing lead defects and thus improving the light conversion efficiency of the device.

[0110] (2) The ultraviolet absorption and fluorescence spectra of the perovskite absorber layers obtained in Example 1 and Comparative Example 1 were tested, and the results are as follows: Figure 2 (ultraviolet absorption spectrum) and Figure 3 (Fluorescence spectrum) as shown; by Figure 2 It can be seen that FA after gel treatment 0.95 MA 0.05 The absorption peak of the PbI3 perovskite light-absorbing layer shows a slight red shift, mainly because the gel effectively promotes the crystallization of the perovskite film, resulting in a larger size of the final perovskite. Meanwhile, after gel treatment, FA... 0.95 MA 0.05 The fluorescence spectrum of the PbI3 perovskite absorbing layer (e.g.) Figure 3 The improvement is significant, further indicating that the amide groups in this gel can effectively passivate defects in perovskites, Pb 2+ It can coordinate with the sulfate groups of K-carrageenan, reducing non-radiative recombination.

[0111] (3) The open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) of the flexible perovskite solar cells provided in Examples 1 to 7 and Comparative Examples 1 and 2 were tested. The test results are shown in Table 1.

[0112] (4) Taking the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 as examples, the stability of the flexible perovskite solar cells was tested, and the results are as follows: Figure 4 As shown in the comparison chart of the stability of perovskite solar cells ( Figure 4It can be seen that the conversion efficiency of perovskite solar cells after gel treatment can still maintain about 90% of the initial value after 1000 hours, while the untreated solar cells degrade faster. This is mainly due to the Pb content. 2+ It can coordinate with the sulfate groups of K-carrageenan, effectively inhibiting ion migration and enhancing battery stability. Furthermore, the greater the gel content, the better the stability.

[0113] (5) Taking the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 as examples, the PCE change over time was tested when the bending radius was 5 mm. The results are as follows: Figure 5 As shown; by Figure 5 It is evident that the bending resistance of perovskite solar cells is significantly improved after gel treatment. This is because the cross-linked polyacrylamide (PAAm) network gives the gel its flexible properties, preventing further bending that could lead to cell structural breakage and effectively improving the mechanical properties of flexible perovskite solar cells. Furthermore, the greater the amount of gel, the better the mechanical properties.

[0114] (6) Taking the flexible perovskite solar cells provided in Examples 1-5 and Comparative Example 1 as examples, the lead concentration in their aqueous solution after soaking for 8 hours was tested, and the results are as follows: Figure 6 As shown, by Figure 6 It can be seen that Pb in the aqueous solution of Comparative Example 1 2+ The concentration was 0.3774 ppm, while the Pb concentration of the solar cell after gel treatment was... 2+ The concentrations of all samples decreased significantly, further demonstrating that Pb 2+ It can coordinate with the sulfate group of K-carrageenan, thus stably holding Pb 2+ This fixation significantly reduces lead leakage from the device. Furthermore, the greater the amount of gel, the better the effect of suppressing lead leakage.

[0115] Table 1

[0116] Voc (V) Jsc(mA / cm 2 )]]> FF (%) PCE (%) Example 1 1.21 24.8 77.9 23.4 Example 2 1.20 24.9 77.7 23.2 Example 3 1.20 25.1 77.5 23.3 Example 4 1.19 24.2 76.8 22.1 Example 5 1.18 24.4 76.5 22.0 Example 6 1.17 24.5 76.7 22.0 Example 7 1.18 24.1 76.6 21.8 Comparative Example 1 1.13 23.9 75.9 20.5 Comparative Example 2 1.15 23.1 76.2 20.2

[0117] As shown in Table 1, the open-circuit voltage of the flexible perovskite solar cell provided by this invention is 0.17–1.21 V, and the short-circuit current is 24.1–25.1 mA / cm². 2The fill factor is 76.5–77.9%, and the conversion efficiency is 21.8–23.4%. Compared with Comparative Example 1, the flexible perovskite solar cell provided by the present invention, by setting a hydrogel layer between the electron transport layer and the perovskite light-absorbing layer, and the material of the hydrogel layer includes cross-linked polyacrylamide-carrageenan gel, significantly improves the open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency of the flexible perovskite solar cell; the PCE of the flexible perovskite solar cell can reach 23% or higher.

[0118] As can be seen from Examples 1, 4, and 5, when the thickness of the gel layer is not within a specific range, and when the amount of gel is too large, the poor conductivity of organic matter will directly affect the efficiency of the battery; if the amount of gel is too small, it will lead to poor passivation effect and will also affect the light conversion efficiency of the battery.

[0119] As can be seen from Examples 1, 6, 7 and Comparative Example 2, when the ratio of carrageenan to acrylamide in the gel layer is not within a specific range or there is no carrageenan, the conversion efficiency of the flexible perovskite solar cell is reduced.

[0120] The applicant declares that 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 comprises a substrate, an electron transport layer, a hydrogel layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode arranged sequentially. The hydrogel layer is made of cross-linked polyacrylamide-carrageenan gel.

2. The flexible perovskite solar cell according to claim 1, characterized in that, The thickness of the hydrogel layer is 2–5 nm.

3. The flexible perovskite solar cell according to claim 1 or 2, characterized in that, The raw materials for preparing the crosslinked polyacrylamide-carrageenan gel include acrylamide monomers, crosslinking agents, initiators, and carrageenan; Preferably, the mass ratio of the acrylamide monomer to carrageenan is 1:(0.5-2); Preferably, the acrylamide monomer includes acrylamide; Preferably, the carrageenan includes K-carrageenan; Preferably, the mass ratio of the crosslinking agent to the acrylamide monomer is (0.0005~0.003):1; Preferably, the crosslinking agent comprises N,N'-methylenebisacrylamide; Preferably, the mass ratio of the initiator to the acrylamide monomer is (0.005-0.02):1; Preferably, the initiator comprises at least one of 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenylacetone, 1-hydroxycyclohexylbenzophenone, benzophenone, or 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

4. The flexible perovskite solar cell according to any one of claims 1 to 3, characterized in that, The general structural formula of the perovskite light-absorbing layer is ABX3; Wherein, A is selected from CH3NH3 + CH(NH2)2 + Cs + or Rb + B is any one or at least two of the following; B is selected from Sn. 2+ Pb 2+ Or Ge 2+ X is any one or at least two of the following, where X is selected from Cl. - ,Br - Or I - Any one or at least two of them; Preferably, the thickness of the perovskite light-absorbing layer is 300–700 nm; Preferably, the material of the electron transport layer includes any one or a combination of at least two of fullerenes and their derivatives, titanium dioxide, tin dioxide, zinc oxide, or zinc oxide doped with zinc sulfide; Preferably, the thickness of the electron transport layer is 15–45 nm.

5. The flexible perovskite solar cell according to any one of claims 1 to 4, characterized in that, The hole transport layer is made of any one or a combination of at least two of the following materials: 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, [4-(9H-carbazole-9-yl)ethyl]phosphonic acid, nickel oxide, cuprous iodide, or cuprous thiocyanate. Preferably, the thickness of the hole transport layer is 10–300 nm; Preferably, the substrate comprises a flexible substrate and a conductive layer disposed sequentially, wherein the conductive layer is stacked with an electron transport layer; Preferably, the conductive layer comprises any one of an indium tin oxide conductive layer, a fluorine-doped SnO2 conductive layer, or an aluminum-doped ZnO conductive layer; Preferably, the thickness of the flexible substrate is 1–4 μm; Preferably, the thickness of the conductive layer is 100–150 nm; Preferably, the electrode comprises a metal electrode and / or a carbon electrode; Preferably, the metal electrode includes at least one of an aluminum electrode, a gold electrode, a silver electrode, or a copper electrode; Preferably, the thickness of the metal electrode is 40–150 nm; Preferably, the carbon electrode comprises a low-temperature carbon electrode; Preferably, the thickness of the carbon electrode is 5–25 μm.

6. A method for fabricating a flexible perovskite solar cell according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: The flexible perovskite solar cell is obtained by sequentially stacking a substrate, an electron transport layer, a hydrogel layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode.

7. The preparation method according to claim 6, characterized in that, A cross-linked polyacrylamide-carrageenan gel was coated onto the surface of the electron transport layer and annealed to obtain the hydrogel layer.

8. The preparation method according to claim 7, characterized in that, The preparation method of the crosslinked polyacrylamide-carrageenan gel includes: mixing acrylamide monomers, crosslinking agents, initiators and carrageenan, and irradiating with ultraviolet light to obtain the crosslinked polyacrylamide-carrageenan gel; Preferably, the intensity of the ultraviolet irradiation is 100–300 mW / cm². 2 The time is 1 to 2 hours.

9. The preparation method according to claim 7 or 8, characterized in that, The coating process is performed at a rotation speed of 2000–4000 rpm for a duration of 30–60 s. Preferably, the annealing temperature is 100–200°C and the time is 10–40 min.

10. A flexible electronic product, characterized in that, The flexible electronic product includes the flexible perovskite solar cell according to any one of claims 1 to 5.

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