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 toughening layer and a perovskite light absorption layer, the preparation raw material of the toughening layer comprises alpha-lipoic acid; the preparation raw materials of the perovskite light absorption layer comprise a perovskite precursor material and an additive; the additive comprises alpha-lipoic acid and other small molecular compounds containing disulfide bonds; the other disulfide bond-containing small molecular compounds have amino groups, hydroxyl groups or carboxyl groups. The flexible perovskite solar cell provided by the invention has good mechanical stability, and the initial efficiency of 85% or above can still be maintained after 5000 times of bending cycles (the bending radius of 5mm).

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. Specifically, it relates to a high-efficiency self-healing flexible perovskite solar cell based on a multi-component dynamic disulfide bond synergistic system and its preparation method. Background Technology

[0002] Perovskite, as a "soft crystal" material, possesses the mechanical characteristics of flexible materials, capable of withstanding a certain degree of compression, deformation, and bending. Flexible perovskite solar cells (F-PSCs), with their unique advantages such as compatibility with wet processing, high power-to-weight ratio, and curved surface bonding, have shown great potential in mobile portable electronic products, wearable smart devices, automotive photovoltaics, and building-integrated photovoltaics, significantly overcoming the limitations of traditional crystalline silicon solar cells in distributed applications. However, mechanical stability has become a key bottleneck restricting the development of flexible perovskite solar cells. During heat treatment, the mechanical adhesion between interfaces on the flexible substrate is greatly reduced, making the film prone to microcracks and interface delamination under external bending stress and fluctuations in ambient temperature and humidity. Simultaneously, during thermal annealing, residual stress is generated in the perovskite light-absorbing layer due to the mismatch in thermal expansion coefficients between functional layers. Once the accumulation of these stresses exceeds a critical threshold, it leads to distortion of the microcrystalline structure, causing band bending, and also reduces the activation energy for ion migration and the formation energy of halogen vacancy defects, thereby accelerating phase separation and perovskite degradation.

[0003] Currently, the mechanical durability challenges faced by flexible perovskite solar cells stem from the inherent characteristics of polycrystalline perovskite films: high Young's modulus, residual stress accumulated during thermal annealing, and grain boundary brittleness. These factors collectively lead to insufficient elastic deformation capacity, resulting in irreversible performance loss when the device undergoes cyclic bending. Although existing technologies can repair grain boundary cracks by introducing self-healing polymers, limitations remain, restricting their practical application. First, the self-healing process often relies on strong external stimuli such as ultraviolet light (wavelength <400nm) and high temperature (>100℃). However, high-energy ultraviolet light accelerates ion migration within the device, inducing chemical degradation at the interface and causing photovoltaic performance degradation. Second, some self-healing materials typically possess insulating properties, leading to an increase in the charge transport barrier at the perovskite and interface, affecting carrier extraction and transport efficiency.

[0004] Therefore, it is desirable in this field to develop a flexible perovskite solar cell that can self-heal at operating temperatures while exhibiting high device efficiency and 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. Specifically, addressing the mechanical durability challenges faced by flexible perovskite solar cells, the present invention provides a high-efficiency, self-healing flexible perovskite solar cell based on a multi-component dynamic disulfide bond synergistic system, exhibiting resistance to bending and stretching, and its fabrication method. The present invention introduces a natural polymerizable small molecule α-lipoic acid (LA) and other small molecule compounds containing disulfide bonds with specific functional groups into the perovskite light-absorbing layer. α-Lipoic acid is introduced at the interface between the hole transport layer and the perovskite light-absorbing layer. Under simple low-temperature heat treatment conditions (60-70℃), the autonomous ring-opening polymerization of LA molecules is achieved through the synergistic effect of dynamic covalent disulfide bonds and hydrogen bonds, ultimately forming an elastic polymer network with a cross-linked structure. Simultaneously, by constructing a multi-component dynamic disulfide bond system, the triggering temperature window for self-healing is broadened. Atoms on the functional groups in the synergistic components (other small molecule compounds containing disulfide bonds, such as nitrogen atoms in -NH2) can also interact with uncoordinated lead ions (Pb) in the perovskite. 2+ This unique design strategy forms stable coordination bonds, effectively passivating defects. It significantly enhances the mechanical properties of flexible perovskite solar cells while simultaneously improving their photoelectric performance and self-healing capabilities.

[0006] The flexible perovskite solar cell provided by this invention can activate the self-repair of the dynamic covalent bond network under operating temperature, realize the synergistic passivation of interface contact enhancement and thin film defects, and break through the bottleneck of balancing efficiency and stability of flexible devices.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a flexible perovskite solar cell, the flexible perovskite solar cell comprising a toughening layer and a perovskite light-absorbing layer;

[0009] The raw materials for preparing the toughening layer include α-lipoic acid;

[0010] The raw materials for preparing the perovskite light-absorbing layer include perovskite precursor materials and additives;

[0011] The additives include α-lipoic acid and other small molecule compounds containing disulfide bonds;

[0012] The other small molecule compounds containing disulfide bonds have amino, hydroxyl, or carboxyl groups.

[0013] The flexible perovskite solar cell provided by this invention introduces α-lipoic acid (LA) and other small molecule compounds containing disulfide bonds with specific groups into the perovskite light-absorbing layer during the fabrication process. The combination of these two compounds can form a dynamic polymer cross-linking network in situ during the perovskite crystallization process, which serves as a self-healing toughening layer. This significantly improves the mechanical stability of the perovskite light-absorbing layer and the reliability of the device. In addition, the flexible perovskite solar cell provided by this invention introduces a toughening layer formed by the polymerization of α-lipoic acid, which can further improve the mechanical stability and reliability of the cell. After 5000 bending cycles (5mm bending radius), the flexible perovskite solar cell device can still maintain more than 85% of its initial efficiency. After being immersed in sunlight for a period of time, the efficiency of the bent device can recover to more than 90%.

[0014] Compared to existing technologies that rely on self-healing polymers for solar cell self-repair, this invention offers unique advantages based on a synergistic self-healing system of multi-component dynamic disulfide bond compounds. Its reversible fracture-recombination properties can be activated under mild conditions (60-70°C), enabling crack self-repair through mechanisms such as disulfide bond exchange while maintaining good interfacial contact. In addition to achieving efficient crack repair and maintaining good interfacial contact, atoms on the groups of other disulfide-bonded small molecule compounds in the synergistic components (e.g., nitrogen atoms in -NH2) can also passivate uncoordinated lead ions (Pb) on the surface defects of the perovskite light-absorbing layer. 2+ ), to suppress the occurrence of nonradiative recombination.

[0015] Preferably, the other small molecule compounds containing disulfide bonds include any one or a combination of at least two of 4,4′-dithiodiphenylamine (DTDA), bis(4-hydroxyphenyl) disulfide, and 2,2-dithiodibenzoic acid.

[0016] Preferably, in the perovskite light-absorbing layer, based on the total mass of the perovskite precursor material and additives (100%), the content of the additives is 0.2% to 1%, for example, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, etc.

[0017] Preferably, in the perovskite light-absorbing layer, the mass ratio of α-lipoic acid to other small molecule compounds containing disulfide bonds is (5~15):1, for example, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, etc.

[0018] Preferably, the perovskite precursor material includes any one or a combination of at least two of methyl bromide, formamidine iodoformide, methyl chloromethylamine, lead iodide, cesium iodide, and lead bromide.

[0019] Preferably, the flexible perovskite solar cell further includes a flexible conductive substrate, a hole transport layer, an electron transport layer, a buffer layer, and an electrode stacked sequentially, wherein the toughening layer is disposed between the hole transport layer and the perovskite light-absorbing layer, and the perovskite light-absorbing layer is disposed between the toughening layer and the electron transport layer.

[0020] Preferably, the flexible conductive substrate comprises a conductive oxide and an organic polymer substrate.

[0021] Preferably, the conductive oxide comprises fluorine-doped tin oxide (FTO) and / or indium tin oxide (ITO).

[0022] Preferably, the organic polymer substrate comprises any one of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or polyimide (PI).

[0023] Preferably, the material of the hole transport layer includes poly(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), poly(triethylthiophenol) (P3HT), or nickel oxide (NiO). x Any one or at least two of the following.

[0024] Preferably, the material of the electron transport layer includes C60 and its derivatives, zinc oxide (ZnO), and tin oxide (SnO). x ( ) or any one or a combination of at least two of fullerene derivatives (PCBM).

[0025] Preferably, the material of the buffer layer includes bath copper phosphate (BCP) and / or tin oxide.

[0026] Preferably, the electrode is made of gold, copper, silver, or an alloy containing the aforementioned metals.

[0027] 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:

[0028] (1) A hole transport layer is prepared on a flexible conductive substrate;

[0029] (2) Mix α-lipoic acid with an organic solvent to obtain a mixture;

[0030] (3) Immerse the flexible conductive substrate with the hole transport layer in the mixture and anneal it to obtain the toughened layer;

[0031] (4) Mix the perovskite precursor material, additives and solvent to obtain a perovskite precursor solution;

[0032] (5) Coat the toughened layer with the perovskite precursor solution and anneal to obtain a perovskite light-absorbing layer;

[0033] (6) An electron transport layer is prepared on the perovskite light-absorbing layer;

[0034] (7) A buffer layer is prepared on the electron transport layer;

[0035] (8) An electrode is prepared on the buffer layer to obtain the flexible perovskite solar cell.

[0036] Preferably, the organic solvent in step (2) includes ethanol.

[0037] Preferably, in the mixture described in step (2), the concentration of α-lipoic acid is 20~30 mg / mL, such as 20 mg / mL, 22 mg / mL, 24 mg / mL, 25 mg / mL, 26 mg / mL, 28 mg / mL, 30 mg / mL, etc.

[0038] Preferably, the soaking time in step (3) is 20 to 40 minutes, such as 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0039] Preferably, the annealing temperature in step (3) is 100~120℃, such as 100℃, 105℃, 110℃, 115℃, 120℃, etc., and the annealing time is 10~20 minutes, such as 10 minutes, 15 minutes, 20 minutes, etc.

[0040] Preferably, the solvent in step (4) includes any one or a combination of at least two of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or N-methylpyrrolidone (NMP).

[0041] Preferably, the annealing temperature in step (5) is 90~110℃, such as 90℃, 95℃, 100℃, 105℃, 110℃, etc., and the annealing time is 10~20 minutes, such as 10 minutes, 15 minutes, 20 minutes, etc.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The flexible perovskite solar cell provided by this invention introduces α-lipoic acid (LA) and other small molecule compounds containing disulfide bonds with specific groups into the perovskite light-absorbing layer during the fabrication process. The combination of these two compounds can form a dynamic polymer cross-linking network in situ during the perovskite crystallization process, which serves as a self-healing toughening layer. This significantly improves the mechanical stability of the perovskite light-absorbing layer and the reliability of the device. In addition, the flexible perovskite solar cell provided by this invention introduces a toughening layer formed by the polymerization of α-lipoic acid, which can further improve the mechanical stability and reliability of the cell. After 5000 bending cycles (5mm bending radius), the flexible perovskite solar cell device can still maintain more than 85% of its initial efficiency. After being immersed in sunlight for a period of time, the efficiency of the bent device can recover to more than 90%. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the flexible perovskite solar cell provided in Example 1;

[0045] Among them, 1-flexible conductive substrate, 2-hole transport layer, 3-toughening layer, 4-perovskite light-absorbing layer, 5-electron transport layer, 6-buffer layer, and 7-metal electrode.

[0046] Figure 2 This is a schematic diagram showing the formation of a cross-linked elastic polymer network by the autonomous ring-opening polymerization of small molecule LA in the flexible perovskite solar cell provided in Example 1 under mild heat treatment conditions.

[0047] Figure 3 SEM images of the perovskite light-absorbing layer in the flexible perovskite solar cells before and after bending, provided in Example 1 and Comparative Example 1.

[0048] Figure 4 The graph shows the Young's modulus test results of the flexible perovskite solar cells provided in Example 1 and Comparative Example 1.

[0049] Figure 5 This is a schematic diagram of the self-healing of the perovskite light-absorbing layer of the flexible perovskite solar cell provided in Example 1 under light immersion conditions.

[0050] Figure 6 Normalized graphs of photoelectric conversion efficiency of flexible perovskite solar cells provided in Example 1 and Comparative Example 1 after cyclic bending and light immersion.

[0051] Figure 7 The photoelectric performance (IV) curves of the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 before and after bending are shown. Detailed Implementation

[0052] 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.

[0053] Unless otherwise specified, the flexible conductive substrate used in the following embodiments and comparative examples of the present invention is polyethylene naphthalate (PEN).

[0054] Example 1

[0055] This embodiment provides a flexible perovskite solar cell, the schematic diagram of which is shown below. Figure 1 As shown, the flexible perovskite solar cell comprises, from bottom to top, a flexible conductive substrate 1, a hole transport layer 2, a toughening layer 3, a perovskite light-absorbing layer 4, an electron transport layer 5, a buffer layer 6, and a metal electrode 7.

[0056] The method for fabricating the flexible perovskite solar cell includes the following steps:

[0057] (1) Prepare a flexible conductive substrate and perform plasma treatment for later use;

[0058] (2) Nickel oxide was deposited as a hole transport layer (120 nm thick) on a flexible conductive substrate after plasma treatment. Then the substrate with the hole transport layer deposited was immersed in an ethanol solution (25 mg / mL) containing α-lipoic acid for 30 minutes. Subsequently, it was annealed on a hot plate at a temperature of 120 °C for 20 min to obtain a toughened layer.

[0059] (3) Mix 200 μL of dimethyl sulfoxide and 800 μL of N,N-dimethylformamide evenly, then add 4.824 mg of α-lipoic acid and 0.50 mg of 4,4′-dithiodiphenylamine, followed by 8 mg of methyl bromide, 232.8 mg of formamidinium iodide, 20.2 mg of chloromethylamine, 656 mg of lead iodide, 19.5 mg of cesium iodide and 28.2 mg of lead bromide to obtain a perovskite precursor solution;

[0060] (4) The perovskite precursor solution is coated on the toughened layer and annealed at 100°C for 15 minutes to obtain a perovskite light-absorbing layer.

[0061] (5) C is deposited on the perovskite light-absorbing layer. 60 As an electron transport layer (25 nm thick);

[0062] (6) BCP is deposited on the electron transport layer as a buffer layer (7 nm thick).

[0063] (7) Silver is deposited on the buffer layer as a metal electrode (thickness of 100 nm) to obtain the flexible perovskite solar cell.

[0064] In this embodiment, 4,4′-dithiodiphenylamine (DTDA) and naturally polymerizable small molecule α-lipoic acid (LA) were introduced into the perovskite precursor solution. α-Lipoic acid was also introduced at the interface between the perovskite light-absorbing layer and the hole transport layer. Under mild heating conditions, LA can undergo autonomous ring-opening polymerization via dynamic disulfide bonds and hydrogen bonds to form a cross-linked elastic polymer network, as shown in the schematic diagram below. Figure 2 As shown.

[0065] Example 2

[0066] The only difference between this embodiment and Example 1 is that the composition of the perovskite precursor solution is different. The perovskite precursor solution in this embodiment is composed of: 8 mg of methyl bromide, 232.8 mg of formamidinium iodide, 20.2 mg of methyl chloromethamine, 656 mg of lead iodide, 19.5 mg of cesium iodide, 28.2 mg of lead bromide, 4.824 mg of α-lipoic acid, and 1.00 mg of bis(4-hydroxyphenyl) disulfide. The solvent is 200 μL of dimethyl sulfoxide and 800 μL of N,N-dimethylformamide.

[0067] Example 3

[0068] The only difference between this embodiment and Example 1 is the composition of the perovskite precursor solution. The perovskite precursor solution in this embodiment consists of: 8 mg of methyl bromide, 232.8 mg of formamidinium iodide, 20.2 mg of methyl chloromethylamine, 656 mg of lead iodide, 19.5 mg of cesium iodide, 28.2 mg of lead bromide, 4.824 mg of α-lipoic acid, and 0.5 mg of 2,2-dithiodibenzoic acid. The solvent is 200 μL of dimethyl sulfoxide and 850 μL of N,N-dimethylformamide.

[0069] Comparative Example 1

[0070] The only difference between this comparative example and Example 1 is that the flexible perovskite solar cell does not include a toughening layer, and α-lipoic acid and 4,4′-dithiodiphenylamine are not added to the perovskite precursor solution.

[0071] Comparative Example 2

[0072] The only difference between this comparative example and Example 1 is that 4,4′-dithiodiphenylamine was not added to the perovskite precursor solution.

[0073] Comparative Example 3

[0074] The only difference between this comparative example and Example 1 is that the flexible perovskite solar cell does not include a toughening layer.

[0075] Comparative Example 4

[0076] The only difference between this comparative example and Example 1 is that the 4,4′-dithiodiphenylamine in the perovskite precursor solution is replaced with an equal mass of dibenzyl disulfide.

[0077] The initial flexible perovskite solar cells provided in the embodiments and comparative examples of this invention were tested for current-voltage characteristics (IV test) under standard sunlight (AM 1.5G). The photovoltaic parameters of the flexible perovskite solar cells include open-circuit voltage (V). oc ), short-circuit current density (J sc The test instruments include a solar simulator and a digital source meter. The solar simulator measures a light intensity of 100 mW / cm². 2 The effective area of ​​the battery is 0.04 cm². 2 .

[0078] The flexible perovskite solar cells provided in the embodiments and comparative examples of the present invention were bent 5000 times (5mm bending radius), and then current-voltage test (IV test) and photoelectric conversion efficiency (PCE) test were performed again.

[0079] The performance test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As can be seen from Table 1, the flexible perovskite solar cell provided in the embodiments of the present invention has good mechanical stability. After being cyclically bent 5000 times at a curvature radius of 5 mm, the photoelectric conversion efficiency can still be maintained at more than 85% of the original value.

[0083] Compared to Example 1, the flexible perovskite solar cell in Comparative Example 1 showed a significant decrease in photoelectric conversion efficiency after 5000 bending cycles. Meanwhile, the cells in Comparative Examples 2, 3, and 4 maintained 79%, 81.7%, and 75% of their initial efficiencies, respectively, under the same conditions, indicating a decrease in photoelectric conversion efficiency retention compared to the Example 1.

[0084] The perovskite light-absorbing layer in the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 before and after bending was characterized by SEM, and the results are as follows: Figure 3As shown, it can be seen that the surface morphology of the perovskite light-absorbing layer in Comparative Example 1 changed significantly after bending, with cracks appearing along the grain boundaries, while the surface morphology of the perovskite light-absorbing layer in Example 1 remained basically unchanged after bending.

[0085] The Young's modulus of the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 was tested, and the test results are as follows: Figure 4 As shown, the Young's modulus of Example 1 is 10.6 GPa, which is much lower than that of Comparative Example 1 (21.7 GPa). This indicates that the cross-linked elastic polymer network with self-healing function can release the stress distributed along the grain boundaries and improve the mechanical durability of the film.

[0086] Figure 5 This is a schematic diagram of the self-healing of the perovskite light-absorbing layer of the flexible perovskite solar cell provided in Example 1 under light immersion conditions. Under the mechanical stress of repeated bending, the perovskite light-absorbing layer is prone to cracks and interface delamination. After being placed under continuous sunlight (the operating temperature can reach 60-70℃), the dynamic disulfide bonds in LA undergo autonomous ring-opening polymerization to form a cross-linked elastic polymer network. The polymer chain segments migrate to the crack area, filling and repairing the grain boundary defects.

[0087] Normalized power conversion efficiency graphs of the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 after cyclic bending and light immersion are shown below. Figure 6 As shown; the photoelectric performance (IV) curves of the flexible perovskite solar cells provided in Example 1 and Comparative Example 1 before and after bending are shown in the figure. Figure 7 As shown, the perovskite light-absorbing layer of Example 1 has fewer surface defects, which is beneficial for carrier transport, resulting in higher photoelectric conversion efficiency and fill factor. Under the same bending conditions (bending radius of 5 mm), the flexible perovskite solar cell of Example 1 exhibits excellent bending stability, maintaining 86% of its initial photoelectric conversion efficiency after 5000 cycles, while the flexible perovskite solar cell of Comparative Example 1 only maintains 28% of its initial photoelectric conversion efficiency. The test results indicate that the flexible perovskite device incorporating dynamic disulfide polymer has superior mechanical bending resistance.

[0088] In summary, this invention provides a toughening design for flexible perovskite solar cells using materials containing dynamic chemical bonds. As illustrated by the examples, a self-healing cross-linked elastic polymer network toughening layer was successfully constructed through the synergistic effect of dynamic disulfide and hydrogen bonds in LA molecules under mild heat treatment conditions (60-70℃). Experimental data show that this self-healing toughening layer does indeed optimize the mechanical stability of flexible perovskite devices, and this optimization is reflected in the perovskite film morphology, Young's modulus comparison, and the efficiency normalization curves of the flexible device at different bending cycles. Comparing the two, with increasing bending cycles, cracks inevitably formed at the grain boundaries of the sample provided in Comparative Example 1, resulting in a significant change in surface morphology. In contrast, the morphology of the treated flexible perovskite film remained essentially unchanged. Atomic force microscopy confirmed that the Young's modulus of the treated flexible perovskite film was significantly reduced, and its flexibility was significantly improved. More importantly, the flexible perovskite solar cells with the introduced toughening layer maintained an efficiency of over 85% of their original value after 5000 cycles of bending at a curvature radius of 5 mm. Furthermore, damaged devices recovered to over 90% efficiency after sunlight exposure, demonstrating excellent self-healing properties. This technology not only solves the key problem of poor mechanical stability in flexible perovskite devices but also provides an innovative solution for large-area, mass-producible fabrication of high-performance flexible photovoltaic devices, holding significant application value in mobile energy, building-integrated photovoltaics, and portable wearable devices.

[0089] This invention addresses the critical bottleneck of mechanical stability in flexible perovskite solar cells by innovatively proposing a self-healing and toughening technology based on dynamic covalent bonds. By introducing the naturally polymerizable small molecule α-lipoic acid into the perovskite precursor solution and interface layer, and under low-temperature heat treatment at 60-70℃, a cross-linked elastic polymer (Poly(LA)) network is autonomously formed through the synergistic effect of dynamic disulfide bonds (-SS-) and hydrogen bonds. This technology offers three major innovative advantages: First, it achieves self-healing of grain boundary cracks through a reversible breakage-reorganization mechanism of dynamic chemical bonds, enabling the device to maintain over 85% of its initial efficiency after 5000 cycles at a 5 mm bending radius. Second, the LA molecule possesses both interface passivation and toughening functions, optimizing the perovskite / functional layer interface contact to promote carrier transport and significantly reducing the Young's modulus of the thin film to improve flexibility. Third, the mild low-temperature treatment process avoids the problems of accelerated ion migration and performance degradation caused by traditional UV light or high-temperature repair methods. This invention breaks through the technical bottleneck of balancing mechanical stability and photoelectric performance in flexible perovskite devices, providing a high-performance flexible photovoltaic solution for emerging application fields such as mobile wearable devices.

[0090] The applicant declares that the flexible perovskite solar cell and its preparation method are illustrated by the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments 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, additions of auxiliary components, and 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 includes a toughening layer and a perovskite light-absorbing layer; The raw materials for preparing the toughening layer include α-lipoic acid; The raw materials for preparing the perovskite light-absorbing layer include perovskite precursor materials and additives; The additives include α-lipoic acid and other small molecule compounds containing disulfide bonds; The other small molecule compounds containing disulfide bonds have amino, hydroxyl, or carboxyl groups.

2. The flexible perovskite solar cell according to claim 1, characterized in that, The other small molecule compounds containing disulfide bonds include any one or a combination of at least two of 4,4′-dithiodiphenylamine, bis(4-hydroxyphenyl) disulfide, and 2,2-dithiodibenzoic acid.

3. The flexible perovskite solar cell according to claim 1 or 2, characterized in that, In the perovskite light-absorbing layer, the content of the additives is 0.2% to 1%, based on the total mass of the perovskite precursor material and the additives being 100%.

4. The flexible perovskite solar cell according to any one of claims 1-3, characterized in that, In the perovskite light-absorbing layer, the mass ratio of α-lipoic acid to other small molecule compounds containing disulfide bonds is (5~15):

1.

5. The flexible perovskite solar cell according to any one of claims 1-4, characterized in that, The perovskite precursor material includes any one or a combination of at least two of the following: methyl bromide, formamidine iodoformide, methyl chloromethylamine, lead iodide, cesium iodide, and lead bromide.

6. The flexible perovskite solar cell according to any one of claims 1-5, characterized in that, The flexible perovskite solar cell further includes a flexible conductive substrate, a hole transport layer, an electron transport layer, a buffer layer, and an electrode stacked sequentially. The toughening layer is disposed between the hole transport layer and the perovskite light-absorbing layer, and the perovskite light-absorbing layer is disposed between the toughening layer and the electron transport layer.

7. The flexible perovskite solar cell according to claim 6, characterized in that, The flexible conductive substrate includes conductive oxide and organic polymer substrates; Preferably, the conductive oxide comprises fluorine-doped tin oxide and / or indium tin oxide; Preferably, the organic polymer substrate comprises any one of polyethylene naphthalate, polyethylene terephthalate, or polyimide; Preferably, the material of the hole transport layer includes any one or a combination of at least two of poly(4-phenyl)(2,4,6-trimethylphenyl)amine, polytrihexylthiophenol, or nickel oxide; Preferably, the material of the electron transport layer includes any one or a combination of at least two of C60 and its derivatives, zinc oxide, tin oxide, or fullerene derivatives; Preferably, the material of the buffer layer includes copper bath and / or tin oxide; Preferably, the electrode is made of gold, copper, silver, or an alloy containing the aforementioned metals.

8. A method for preparing a flexible perovskite solar cell as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) A hole transport layer is prepared on a flexible conductive substrate; (2) Mix α-lipoic acid with an organic solvent to obtain a mixture; (3) Immerse the flexible conductive substrate with the hole transport layer in the mixture and anneal it to obtain the toughened layer; (4) Mix the perovskite precursor material, additives and solvent to obtain a perovskite precursor solution; (5) Coat the toughened layer with the perovskite precursor solution and anneal to obtain a perovskite light-absorbing layer; (6) An electron transport layer is prepared on the perovskite light-absorbing layer; (7) A buffer layer is prepared on the electron transport layer; (8) An electrode is prepared on the buffer layer to obtain the flexible perovskite solar cell.

9. The preparation method according to claim 8, characterized in that, The organic solvent in step (2) includes ethanol; Preferably, in the mixture described in step (2), the concentration of α-lipoic acid is 20~30 mg / mL; Preferably, the soaking time in step (3) is 20 to 40 minutes; Preferably, the annealing temperature in step (3) is 100~120℃ and the annealing time is 10~20 minutes.

10. The preparation method according to claim 8 or 9, characterized in that, The solvent in step (4) includes any one or a combination of at least two of N,N-dimethylformamide, dimethyl sulfoxide, or N-methylpyrrolidone; Preferably, the annealing temperature in step (5) is 90~110℃ and the annealing time is 10~20 minutes.

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