Perovskite solar cell and preparation method thereof

Abstract

The invention provides a perovskite solar cell and a preparation method thereof. The perovskite solar cell comprises a transparent conductive substrate, a first carrier transport layer, a perovskite active layer, a second carrier transport layer and a metal electrode layer which are sequentially stacked, a functional layer is further arranged between the first carrier transport layer and the perovskite active layer, and the functional layer is made of hyperbranched polymer. The hyperbranched polymer is selected from one or more of polyamide with a hyperbranched structure, polyimide, polyether ester and polycarbonate, and the branching degree of the hyperbranched polymer is 0.5-0.8. The hyperbranched polymer of the kind is used as the material of the functional layer, so that the mechanical strength of the perovskite solar cell can be improved, the impact resistance of the perovskite solar cell can be improved, and the change of mechanical internal stress can be absorbed; and meanwhile, HI and I2 generated by decomposition of the perovskite active material can be blocked and absorbed, so that the risk of lead leakage when the perovskite solar cell is damaged is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and in particular to a perovskite solar cell and a preparation method thereof. Background Art

[0002] In recent years, organic-inorganic hybrid perovskite solar cells have attracted widespread attention due to their high absorption coefficient, adjustable band gap, long carrier diffusion length and large-scale manufacturing characteristics. From materials to preparation processes, their laboratory photoelectric conversion efficiency has exceeded the 26.1% mark. One of the most attractive features is their low cost and solution-based processing, which makes them more universal than traditional crystalline silicon solar cells.

[0003] Currently, researchers are mainly focusing on the reliability and large-scale commercial application of perovskite solar cells, but the mechanical stress during the manufacturing process remains largely unexplored, limiting the reliability of perovskite solar cells. Therefore, the commercialization of perovskite solar cells depends on their mechanical reliability.

[0004] Perovskite solar cells are layered structures containing multiple film layers, each with different mechanical properties. Previous studies have shown that the bonding fracture energy between the film layers of perovskite solar cells is lower than that of crystalline silicon solar cells. Specifically, the interface bonding between the carrier transport layer and the perovskite active layer is particularly fragile. When external forces are applied during lamination of the components or outdoor use, small cracks that may form will transform into larger cracks during subsequent cycles, causing device delamination or even fracture. Therefore, weaker interfacial bonding energy is a key factor that hinders the improvement of the yield and optoelectronic performance of perovskite solar cells.

[0005] At present, some researchers have tried to alleviate the interface stratification problem in perovskite solar cells by interface modification, such as setting an interface buffer layer and constructing a dendrite network structure. For example, (1) using polystyrene as an interface buffer can reduce the residual stress during annealing, thereby reducing interface defects and improving device performance; (2) introducing an adhesive polymer (such as ethylene-vinyl acetate, or EVA) between SnO2 and perovskite can improve interface contact and increase fracture toughness, thereby achieving better performance and mechanical stability. However, these interface modification methods usually use small molecules or linear polymers, which are limited in their ability to improve interface strength and ductility.

[0006] On this basis, researching and developing a functional layer that can significantly improve the interface strength and inhibit the decomposition of perovskite active materials and lead leakage is of great significance for improving the yield and safety of perovskite solar cells. Summary of the invention

[0007] The main purpose of the present invention is to provide a perovskite solar cell and a preparation method thereof, so as to solve the problems of poor mechanical stability and safety of the perovskite solar cell caused by poor interface strength between film layers and decomposition of perovskite active materials and lead leakage in the prior art.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a perovskite solar cell on one hand, comprising a transparent conductive substrate, a first carrier transport layer, a perovskite active layer, a second carrier transport layer and a metal electrode layer stacked in sequence, a functional layer is further arranged between the first carrier transport layer and the perovskite active layer, the material of the functional layer comprises a hyperbranched polymer, the hyperbranched polymer is selected from one or more of the group consisting of polyamide, polyimide, polyether ester and polycarbonate having a hyperbranched structure, and the branching degree of the hyperbranched polymer is 0.5 to 0.8.

[0009] Furthermore, the hyperbranched polymer is a polyamide with a hyperbranched structure, whose branching degree is 0.5 to 0.8 and whose weight average molecular weight is 100,000 to 150,000. Preferably, the branched ends of the polyamide with a hyperbranched structure include carboxyl groups, amide groups, and primary amine groups, and preferably, the weight percentage of the grafted groups at the branched ends of the polyamide with a hyperbranched structure is 2 to 5 wt%.

[0010] Furthermore, the hyperbranched polymer is a polyimide with a hyperbranched structure, whose branching degree is 0.55 to 0.7 and the weight average molecular weight is 10,000 to 13,000. Preferably, the branched ends of the polyimide with a hyperbranched structure include amino groups, carboxyl groups, and imino groups, and preferably, the weight percentage of the grafted groups at the branched ends of the polyimide with a hyperbranched structure is 2 to 5 wt%.

[0011] Furthermore, the hyperbranched polymer is a polyether ester with a hyperbranched structure, whose branching degree is 0.6 to 0.8 and the weight average molecular weight is 15,000 to 20,000. Preferably, the branch ends of the polyether ester with a hyperbranched structure include amino groups, carboxyl groups, and imino groups, and preferably, the weight percentage of the grafted groups at the branch ends of the polyether ester with a hyperbranched structure is 1 to 4 wt%.

[0012] Furthermore, the hyperbranched polymer is a polycarbonate with a hyperbranched structure, whose branching degree is 0.5 to 0.8 and the weight average molecular weight is 12000 to 18000. Preferably, the branched ends of the polycarbonate with a hyperbranched structure include one or more of amino, carboxyl, and imino groups, and preferably, the weight percentage of the grafted groups at the branched ends of the polycarbonate with a hyperbranched structure is 2 to 5wt%.

[0013] Furthermore, the thickness of the functional layer is 20 to 100 nm, preferably 20 to 45 nm.

[0014] Furthermore, the first carrier transport layer is a hole transport layer, and the second carrier transport layer is an electron transport layer.

[0015] Furthermore, the thickness of the hole transport layer is 20 to 80 nm.

[0016] Furthermore, the thickness of the perovskite active layer is 300-600 nm.

[0017] Furthermore, the thickness of the electron transport layer is 10 to 30 nm.

[0018] Furthermore, the thickness of the metal electrode layer is 100-300 nm.

[0019] Furthermore, the perovskite solar cell also includes an interface modification layer, which is arranged between the electron transport layer and the metal electrode layer; preferably, the thickness of the interface modification layer is 5 to 15 nm; preferably, the material of the interface modification layer is selected from bathocuproin and / or zinc oxide.

[0020] Furthermore, the material of the hole transport layer is selected from NiO x , PTAA and Spiro-OMeTAD.

[0021] Furthermore, the material of the perovskite active layer is selected from ABX3, wherein A is CH3NH3 + NH=CHNH3 + or Cs + , B is Pb 2+ , X is Cl - or Br - .

[0022] Furthermore, the material of the electron transport layer is selected from SnO2, C 60 and PCBM.

[0023] Furthermore, the material of the metal electrode layer is selected from one or more of the group consisting of Au, Ag and Cu.

[0024] Furthermore, the transparent conductive substrate is selected from ITO conductive glass, FTO conductive glass or ZITO conductive glass.

[0025] Furthermore, the first carrier transport layer is a hole transport layer, and the thickness of the hole transport layer is 20 to 80 nm, and the material is NiO x The material of the functional layer is a polyimide with a hyperbranched structure, the branching degree of which is 0.55 to 0.7, and the thickness of the functional layer is 25 to 35 nm; the first carrier transport layer is a hole transport layer, and the thickness of the hole transport layer is 25 to 45 nm, and the material is NiO xThe material of the functional layer is polyimide with a hyperbranched structure, the branching degree of which is 0.6 to 0.7, and the thickness of the functional layer is 25 to 35 nm.

[0026] Furthermore, the material of the perovskite active layer is (CsPbI3) 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05 or (FAPbI3) 1-x (MAPbBr3) x .

[0027] In order to achieve the above-mentioned purpose, another aspect of the present invention also provides a method for preparing the above-mentioned perovskite solar cell provided in the present application, comprising sequentially preparing a first carrier transport layer, a perovskite active layer, a second carrier transport layer and a metal electrode layer on one side surface of a transparent conductive substrate, the preparation method also comprising: preparing a functional layer on the side surface of the first carrier transport layer away from the transparent conductive substrate), the preparation method of the functional layer comprising: mixing a hyperbranched polymer with a solvent to obtain a hyperbranched polymer precursor solution, coating the hyperbranched polymer precursor solution on the side surface of the first carrier transport layer away from the transparent conductive substrate, and obtaining the functional layer after annealing.

[0028] Furthermore, the intrinsic viscosity of the hyperbranched polymer precursor solution is 0.15 to 0.95 dL / g.

[0029] Furthermore, the coating is carried out by ultrasonic spraying. Preferably, during the ultrasonic spraying process, the frequency of the ultrasound is 25 to 180 Hz, the spraying pressure is 20 to 100 kPa, the time is 5 to 30 min, and the distance between the nozzle of the ultrasonic spraying device and the surface of the first carrier transport layer away from the transparent conductive substrate is 5 to 25 cm.

[0030] Furthermore, the annealing temperature is 120-180° C., and the annealing time is 0.4-0.8 h.

[0031] Furthermore, the preparation method further comprises: preparing an interface modification layer on the surface of the second carrier transport layer away from the perovskite active layer, preferably by using atomic layer deposition or plasma deposition to prepare the interface modification layer.

[0032] By applying the technical solution of the present invention, the hyperbranched polymer of the above type adopted in the present invention has high transparency and excellent impact strength and toughness. Using it as the material of the functional layer can not only improve the mechanical strength of the perovskite solar cell and improve its impact resistance, but also absorb the mechanical internal stress changes of the perovskite solar cell, making it suitable for flexible folding battery products; at the same time, since the hyperbranched polymer has a highly branched three-dimensional structure, it can block and absorb HI and I2 generated by the decomposition of the perovskite active material, inhibit the occurrence of subsequent chain decomposition reactions, thereby reducing the risk of lead leakage when the perovskite solar cell is damaged, and improving safety and environmental protection.

[0033] Compared with other types of hyperbranched polymers, the use of hyperbranched polymers with a branching degree in the above-mentioned specific range of the present application as the material of the functional layer is beneficial to improving the interface strength, thereby helping to improve the mechanical strength of the perovskite solar cell; it is also beneficial to better block and absorb HI and I2 generated by the decomposition of perovskite, which is beneficial to improving the safety of the perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0035] Figure 1 A schematic diagram of the stacked structure of a perovskite solar cell in a preferred embodiment of the present invention is shown;

[0036] Figure 2 A schematic diagram of the stacked structure of a perovskite solar cell in another preferred embodiment of the present invention is shown.

[0037] The above drawings include the following reference numerals:

[0038] 10. Transparent conductive substrate; 20. First carrier transport layer; 30. Perovskite active layer; 40. Second carrier transport layer; 50. Metal electrode layer; 60. Functional layer; 70. Interface modification layer. DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0040] As described in the background art, existing perovskite solar cells have problems such as poor interface strength between film layers, decomposition of perovskite active materials, and poor mechanical stability and photoelectric performance of perovskite solar cells caused by lead leakage. In order to solve the above technical problems, the present application provides a perovskite solar cell, such as Figure 1As shown, it includes a transparent conductive substrate 10, a first carrier transport layer 20, a perovskite active layer 30, a second carrier transport layer 40 and a metal electrode layer 50 which are stacked in sequence, and a functional layer 60 is further arranged between the first carrier transport layer 20 and the perovskite active layer 30. The material of the functional layer 60 includes a hyperbranched polymer, and the hyperbranched polymer is selected from one or more of the group consisting of polyamide, polyimide, polyether ester and polycarbonate having a hyperbranched structure, and the branching degree of the hyperbranched polymer is 0.5 to 0.8.

[0041] Hyperbranched polymers are a class of highly branched three-dimensional polymers with spherical or dendritic structures, which endow them with rich functional groups, intramolecular cavities, excellent mechanical strength and toughness, and the ability to form strong interactions with other materials, imparting excellent adhesion properties and other characteristics.

[0042] The hyperbranched polymer of the above type used in the present invention has high transparency and excellent impact strength and toughness. Using it as the material of the functional layer 60 can not only improve the mechanical strength of the perovskite solar cell and improve its impact resistance, but also absorb the mechanical internal stress changes of the perovskite solar cell, making it suitable for flexible folding battery products; at the same time, since the hyperbranched polymer has a highly branched three-dimensional structure, it can block and absorb HI and I2 produced by the decomposition of the perovskite active material, inhibit the occurrence of subsequent chain decomposition reactions, thereby reducing the risk of lead leakage when the perovskite solar cell is damaged, and improving safety and environmental protection.

[0043] Compared with other types of hyperbranched polymers, the use of hyperbranched polymers with a branching degree in the above-mentioned specific range of the present application as the material of the functional layer 60 is beneficial to improving the interface strength, thereby improving the mechanical strength of the perovskite solar cell; it is also beneficial to better block and absorb HI and I2 generated by the decomposition of perovskite, which is beneficial to improving the safety of the perovskite solar cell.

[0044] In a preferred embodiment, the hyperbranched polymer is a polyamide with a hyperbranched structure, and its branching degree is 0.5 to 0.8, and its weight average molecular weight is 100000 to 150000. The branching degree and weight average molecular weight of the polyamide with a hyperbranched structure include but are not limited to the above ranges, and limiting it within the above ranges is conducive to further improving the interface strength, thereby further improving the mechanical strength of the perovskite solar cell; at the same time, it is also conducive to further better blocking and absorbing HI and I2 generated by the decomposition of perovskite, which is conducive to further improving the safety of the perovskite solar cell.

[0045] In order to improve the interface strength between the first carrier transport layer 20 and the perovskite active layer 30, preferably, the branched ends of the polyamide with a hyperbranched structure include carboxyl, amide, and primary amine, and the grafted groups at the branched ends account for 2 to 5 wt% of the weight of the polyamide with a hyperbranched structure. The branched ends of the polyamide with a hyperbranched structure include the above groups, and compared with other ranges, the content of the above grafted groups is limited to the above range, which can form chemical interactions such as hydrogen bonds and coordination bonds with the first carrier transport layer 20 and the perovskite active layer 30, thereby further enhancing the bonding force between the film layers; and even if the laminated structure of the perovskite solar cell is destroyed or broken, the hyperbranched structure of the hyperbranched polymer has the characteristics of high mobility, which can promote the recombination of hydrogen bond donors and acceptors, thereby generating an adaptive dynamic hydrogen bond network, thereby playing a passivation role and improving the photoelectric conversion efficiency of the perovskite solar cell.

[0046] In a preferred embodiment, the hyperbranched polymer is a polyimide with a hyperbranched structure, and its branching degree is 0.55 to 0.7, and its weight average molecular weight is 10000 to 13000. The branching degree and weight average molecular weight of the polyimide with a hyperbranched structure include but are not limited to the above ranges, and limiting it within the above ranges is conducive to further improving the interface strength, thereby further improving the mechanical strength of the perovskite solar cell; at the same time, it is also conducive to further better blocking and absorbing HI and I2 generated by the decomposition of perovskite, which is conducive to further improving the safety of the perovskite solar cell.

[0047] In order to improve the interface strength between the first carrier transport layer 20 and the perovskite active layer 30, preferably, the branched ends of the polyimide with a hyperbranched structure include amino (-NH2), carboxyl (-COOH), and imino (-NH-), and the grafted groups at the branched ends account for 2-5wt% of the weight percentage of the polyimide with a hyperbranched structure. The branched ends of the polyimide with a hyperbranched structure include the above-mentioned groups, and compared with other ranges, the content of the above-mentioned grafted groups is limited to the above-mentioned range, which can form chemical interactions such as hydrogen bonds and coordination bonds between the first carrier transport layer 20 and the perovskite active layer 30, thereby further enhancing the bonding force between the film layers; and, even if the laminated structure of the perovskite solar cell is destroyed or broken, the hyperbranched structure of the hyperbranched polymer has the characteristics of high mobility, which can promote the recombination of hydrogen bond donors and acceptors, thereby generating an adaptive dynamic hydrogen bond network, thereby playing a passivation role and improving the photoelectric conversion efficiency of the perovskite solar cell.

[0048] In a preferred embodiment, the hyperbranched polymer is a polyether ester having a hyperbranched structure, and the branching degree is 0.6 to 0.8, and the weight average molecular weight is 15000 to 20000. The branching degree and weight average molecular weight of the polyether ester having a hyperbranched structure include but are not limited to the above ranges, and limiting it within the above ranges is conducive to further improving the interface strength, thereby further improving the mechanical strength of the perovskite solar cell; at the same time, it is also conducive to further better blocking and absorbing HI and I2 generated by the decomposition of perovskite, which is conducive to further improving the safety of the perovskite solar cell.

[0049] In order to improve the interface strength between the first carrier transport layer 20 and the perovskite active layer 30, preferably, the branched ends of the polyether ester with a hyperbranched structure include amino (-NH2), carboxyl (-COOH), and imino (-NH-), and the grafted groups at the branched ends account for 1 to 4 wt% of the weight of the polyether ester with a hyperbranched structure. The branched ends of the polyether ester with a hyperbranched structure include the above-mentioned groups, and compared with other ranges, the content of the above-mentioned grafted groups is limited to the above-mentioned range, which can form chemical interactions such as hydrogen bonds and coordination bonds with the first carrier transport layer 20 and the perovskite active layer 30, thereby further enhancing the bonding force between the film layers; and even if the laminated structure of the perovskite solar cell is destroyed or broken, the hyperbranched structure of the hyperbranched polymer has the characteristics of high mobility, which can promote the recombination of hydrogen bond donors and acceptors, thereby generating an adaptive dynamic hydrogen bond network, thereby playing a passivation role and improving the photoelectric conversion efficiency of the perovskite solar cell.

[0050] In a preferred embodiment, the hyperbranched polymer is a polycarbonate with a hyperbranched structure, and its branching degree is 0.5 to 0.8, and its weight average molecular weight is 12000 to 18000. The branching degree and weight average molecular weight of the polycarbonate with a hyperbranched structure include but are not limited to the above ranges, and limiting it within the above ranges is conducive to further improving the interface strength, thereby further improving the mechanical strength of the perovskite solar cell; at the same time, it is also conducive to further better blocking and absorbing HI and I2 generated by the decomposition of perovskite, which is conducive to further improving the safety of the perovskite solar cell.

[0051] In order to improve the interface strength between the first carrier transport layer 20 and the perovskite active layer 30, preferably, the branched ends of the polycarbonate with a hyperbranched structure include one or more of an amino group, a carboxyl group, and an imino group, and the grafted groups at the branched ends account for 2 to 5 wt % of the weight percentage of the polycarbonate with a hyperbranched structure. The branched ends of the polycarbonate with a hyperbranched structure include the above-mentioned groups, and compared with other ranges, the content of the above-mentioned grafted groups is limited to the above-mentioned range, which can form chemical interactions such as hydrogen bonds and coordination bonds between the first carrier transport layer 20 and the perovskite active layer 30, thereby further enhancing the bonding force between the film layers; and even if the laminated structure of the perovskite solar cell is destroyed or broken, the hyperbranched structure of the hyperbranched polymer has the characteristics of high mobility, which can promote the recombination of hydrogen bond donors and acceptors, thereby generating an adaptive dynamic hydrogen bond network, thereby playing a passivation role and improving the photoelectric conversion efficiency of the perovskite solar cell.

[0052] In a preferred embodiment, the thickness of the functional layer 60 is 20 to 100 nm. The thickness of the functional layer 60 includes but is not limited to the above range, and limiting it within the above range is conducive to better play the role of enhancing the interface bonding force and interface strength, while ensuring that the photoelectric performance of the perovskite solar cell is maintained at a high level.

[0053] In order to further enhance the interfacial bonding force and interfacial strength and further improve the photoelectric performance of the perovskite solar cell, preferably, the thickness of the functional layer 60 is 20 to 45 nm.

[0054] The stacked structure of the perovskite solar cell provided in the present application may be a commonly used inverted structure (pin structure). In a preferred embodiment, the first carrier transport layer 20 is a hole transport layer, and the second carrier transport layer 40 is an electron transport layer.

[0055] In a preferred embodiment, the thickness of the hole transport layer is 20 to 80 nm, preferably 35 to 65 nm. The thickness of the hole transport layer includes but is not limited to the above range, and limiting it within the above range is conducive to improving the hole transport efficiency, thereby improving the photoelectric performance of the perovskite solar cell.

[0056] In order to further improve the hole transport efficiency, thereby improving the photoelectric conversion efficiency of the perovskite solar cell, preferably, the material of the hole transport layer includes but is not limited to NiO x One or more of the group consisting of polytriarylamine (PTAA) and 2,2',7,7'-tetrakis(N,N-p-methoxyanilino)-9,9'-spirobifluorene (Spiro-OMeTAD).

[0057] In a preferred embodiment, the thickness of the perovskite active layer 30 is 300-600 nm. The thickness of the perovskite active layer 30 includes but is not limited to the above range, and limiting it within the above range is conducive to improving the light absorption efficiency, thereby improving the photoelectric performance of the perovskite solar cell, such as the photoelectric conversion efficiency.

[0058] In order to further improve the light absorption efficiency, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell, preferably, the material of the perovskite active layer 30 includes but is not limited to ABX3, wherein A is CH3NH3 + NH=CHNH3 + or Cs + , B is Pb 2+ , X is Cl - or Br - .

[0059] In a preferred embodiment, the thickness of the electron transport layer is 10 to 30 nm, preferably 20 to 28 nm. The thickness of the electron transport layer includes but is not limited to the above range, and limiting it within the above range is conducive to improving the electron transport efficiency, thereby improving the photoelectric performance of the perovskite solar cell.

[0060] In order to further improve the electron transport efficiency, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell, preferably, the material of the electron transport layer includes but is not limited to SnO2, C 60 and PCBM.

[0061] In a preferred embodiment, the thickness of the metal electrode layer 50 is 100 to 300 nm, preferably 150 to 250 nm. The thickness of the metal electrode layer 50 includes but is not limited to the above range, and limiting it within the above range is conducive to improving the electron transfer efficiency, thereby improving the photoelectric performance of the perovskite solar cell.

[0062] The metal electrode layer 50 in the perovskite solar cell provided in the present application can be made of any commonly used material in the art, without any particular limitation, as long as it has good conductivity. Preferably, the material of the metal electrode layer 50 includes, but is not limited to, one or more of the group consisting of Au, Ag and Cu.

[0063] In order to improve the photoelectric performance and stability of perovskite solar cells, such as the photoelectric conversion efficiency, in a preferred embodiment, Figure 2 As shown, the perovskite solar cell further includes an interface modification layer 70 , and the interface modification layer 70 is disposed between the electron transport layer and the metal electrode layer 50 .

[0064] In order to further improve the photoelectric performance and stability of the perovskite solar cell, such as the photoelectric conversion efficiency, the interface modification layer 70 preferably has a thickness of 5 to 15 nm.

[0065] In a preferred embodiment, the material of the interface modification layer 70 includes but is not limited to bathocuproine (BCP) and / or zinc oxide. Compared with other materials, using the above materials as the material of the interface modification layer 70 is conducive to further improving the photoelectric performance and stability of the perovskite solar cell, such as the photoelectric conversion efficiency.

[0066] The transparent conductive substrate 10 in the perovskite solar cell provided in the present application can be made of a material with high transparency and good conductivity commonly used in the art. Preferably, the transparent conductive substrate 10 includes but is not limited to ITO conductive glass, FTO conductive glass or ZITO conductive glass.

[0067] Arranging a corresponding functional layer 60 for a hole transport layer of a specific type and a specific thickness is conducive to better exerting the role of the functional layer 60 in improving the interface strength and inhibiting lead leakage, and is conducive to better exerting the synergistic effect of the two, thereby facilitating the improvement of the mechanical strength, photoelectric conversion efficiency, safety and stability of the perovskite solar cell. In a preferred embodiment, the first carrier transport layer 20 is a hole transport layer, and the thickness of the hole transport layer is 20 to 80 nm, and the material is NiO x The material of the functional layer 60 is a polyimide with a hyperbranched structure, the degree of branching is 0.55 to 0.7, and the thickness of the functional layer 60 is 25 to 35 nm; or, the first carrier transport layer 20 is a hole transport layer, and the thickness of the hole transport layer is 25 to 45 nm, and the material is NiO x The material of the functional layer 60 is polyimide with a hyperbranched structure, the branching degree of which is 0.6-0.7, and the thickness of the functional layer 60 is 25-35 nm.

[0068] For different perovskite active materials, the corresponding hyperbranched polymer is selected as the material of the functional layer 60, which is conducive to better exerting the role of the functional layer 60 in improving the interface strength and inhibiting lead leakage, and is conducive to improving the adaptability of the two, thereby improving the mechanical strength, photoelectric conversion efficiency, safety and stability of the perovskite solar cell. In a preferred embodiment, the material of the perovskite active layer 30 is (CsPbI3) 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05 or (FAPbI3) 1-x (MAPbBr3) x .

[0069] The second aspect of the present application also provides a method for preparing the above-mentioned perovskite solar cell provided by the present application, comprising sequentially preparing a first carrier transport layer 20, a perovskite active layer 30, a second carrier transport layer 40 and a metal electrode layer 50 on one side surface of a transparent conductive substrate 10, and the above-mentioned perovskite solar cell preparation method also includes: preparing a functional layer 60 on the side surface of the first carrier transport layer 20 away from the transparent conductive substrate 10, and the preparation method of the functional layer 60 includes: mixing a hyperbranched polymer with a solvent to obtain a hyperbranched polymer precursor solution, coating the hyperbranched polymer precursor solution on the side surface of the first carrier transport layer 20 away from the transparent conductive substrate 10, and obtaining the functional layer 60 after annealing.

[0070] The above method can easily arrange the hyperbranched polymer on the surface of one side of the first carrier transport layer 20 away from the transparent conductive substrate 10, thereby forming a functional layer 60. The above functional layer 60 includes a hyperbranched polymer. The arrangement of the functional layer 60 containing the above hyperbranched polymer can improve the mechanical strength of the perovskite solar cell, improve its impact resistance, and absorb the mechanical internal stress changes of the perovskite solar cell, making it suitable for flexible folding battery products; at the same time, because the hyperbranched polymer has a highly branched three-dimensional structure, it can block and absorb HI and I2 generated by the decomposition of the perovskite active material, inhibit the occurrence of subsequent chain decomposition reactions, thereby reducing the risk of lead leakage in the case of damage to the perovskite solar cell, and improving safety and environmental protection. In addition, the preparation process of the above functional layer 60 is simple and easy to operate.

[0071] In a preferred embodiment, the intrinsic viscosity of the hyperbranched polymer precursor solution is 0.15-0.95 dL / g. The mass concentration of the hyperbranched polymer includes but is not limited to the above range, which is conducive to improving its coating processability, thereby facilitating better performance of the functional layer 60.

[0072] Ultrasonic spraying is a coating method that uses ultrasonic waves to atomize a solution into small particles and sprays them on the surface of a target substrate through a carrier gas. Preferably, the coating is carried out by ultrasonic spraying. Compared with the traditional coating method, the ultrasonic spraying method is conducive to improving the uniformity of distribution of the hyperbranched polymer precursor solution on the surface of the first carrier transport layer 20, thereby helping to improve the uniformity of distribution of the functional layer 60, and then helping to better play the role of the functional layer 60, and improving the mechanical strength and safety of the perovskite solar cell.

[0073] In order to further improve the distribution uniformity of the functional layer 60, preferably, during the ultrasonic spraying process, the frequency of ultrasound is 25 to 180 Hz, the spraying pressure is 20 to 100 kPa, the time is 5 to 30 min, and the distance between the nozzle of the ultrasonic spraying device and the surface of the side of the first carrier transport layer 20 away from the transparent conductive substrate 10 is 5 to 25 cm.

[0074] In a preferred embodiment, the annealing temperature is 120-180°C and the time is 0.4-0.8h. The annealing temperature and time include but are not limited to the above ranges, and limiting them within the above ranges is conducive to more fully forming connecting hydrogen bonds between film layers, increasing the bonding capacity, and inhibiting the formation of large void defects, thereby relieving local strain and enhancing stability.

[0075] In order to further improve the interface bonding between the metal electrode layer 50 and the second carrier transport layer 40 (or electron transport layer), thereby further improving the photoelectric performance of the perovskite solar cell, preferably, the preparation method also includes: preparing an interface modification layer 70 on the surface of the second carrier transport layer 40 away from the perovskite active layer 30.

[0076] In order to improve the uniformity of the interface modification layer 70 and facilitate the control of its thickness, preferably, the interface modification layer 70 is prepared by atomic layer deposition or plasma deposition.

[0077] In the present application, the hole transport layer can be prepared by the magnetron sputtering method or spray pyrolysis method commonly used in the art, the perovskite active layer 30 can be prepared by the one-step method or the two-step method commonly used in the art, the electron transport layer can be prepared by the atomic layer deposition method or the plasma deposition method commonly used in the art, and the metal electrode layer 50 can be prepared by the evaporation method or the sputtering method commonly used in the art.

[0078] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0079] Example 1

[0080] A method for preparing a perovskite solar cell, comprising:

[0081] (1) Prepare an ITO conductive glass with a size of 5 cm × 5 cm, use deionized water and ethanol to ultrasonically clean it for 15 min, and blow dry it for later use;

[0082] (2) Preparation of hole transport layer:

[0083] At room temperature and 1×10 -3 Under the vacuum condition of 1.5 Pa, a layer of NiO was formed on the conductive surface of the ITO conductive glass by magnetron sputtering. x, its thickness is 60nm;

[0084] (3) Preparation of functional layer 60:

[0085] A hyperbranched polyimide (HBPI) with a branching degree of 0.75 and a weight average molecular weight of 12000 was mixed with N-methyl-2-pyrrolidone (NMP) to form a hyperbranched polymer precursor solution with an intrinsic viscosity of 0.76 dL / g. The 5% thermal weight loss temperature T of the hyperbranched polyimide was measured by TG. d 5 Above 365℃, DSC measured its T g The temperature is 170°C and the viscosity η is 0.85 dL / g; ultrasonic spraying equipment is used to ultrasonically spray the hole transport layer away from the ITO conductive glass for 20 minutes under the conditions of an ultrasonic frequency of 120 kHz and a spraying pressure of 36 kPa, wherein the distance between the nozzle and the hole transport layer away from the ITO conductive glass is 20 cm, and after annealing, a functional layer 60 with a thickness of 20 nm is obtained;

[0086] (4) Preparation of perovskite active layer 30:

[0087] In a glove box filled with nitrogen, PbI2, PbBr, CsI, FAI and MAI powders were dispersed in 20 mL of DMF at a molar ratio of 2:0.2:0.1:1:0.6, and stirred for 8 h until completely dissolved to obtain a perovskite precursor solution; the perovskite precursor solution was coated on the surface of the functional layer 60 away from the hole transport layer by a slit coating method, and heat treated at 120°C for 20 min to obtain a (CsPbI3) with a thickness of 450 nm. 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05 layer;

[0088] (5) Preparation of electron transport layer:

[0089] In (CsPbI3) 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05 A layer of C with a thickness of 20 nm is deposited on the surface of the layer away from the functional layer 60 by atomic layer deposition. 60 layer;

[0090] (6) Preparation of interface modification layer 70:

[0091] In C 60 Layer away from (CsPbI3) 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05On one side of the layer, a BCP layer with a thickness of 15 nm was deposited by plasma deposition;

[0092] (6) Preparation of metal electrode layer 50:

[0093] In the BCP layer away from C 60 A 200 nm thick Ag layer is deposited on one surface of the layer to obtain a perovskite solar cell.

[0094] The perovskite solar cell has Figure 2 The stacked structure shown is represented by:

[0095] ITO / NiO x / HBPI / (CsPbI3) 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05 / C 60 / BCP / Ag.

[0096] Example 2

[0097] The difference from Example 1 is that the hyperbranched polymer used in step (3) is a polyamide with a hyperbranched structure having a branching degree of 0.5 and a weight average molecular weight of 100,000.

[0098] Example 3

[0099] The difference from Example 1 is that the hyperbranched polymer used in step (3) is a polyimide with a hyperbranched structure having a branching degree of 0.55 and a weight average molecular weight of 10,000.

[0100] Example 4

[0101] The difference from Example 1 is that the hyperbranched polymer used in step (3) is a polyether ester with a hyperbranched structure having a branching degree of 0.6 and a weight average molecular weight of 15,000.

[0102] Example 5

[0103] The difference from Example 1 is that the hyperbranched polymer used in step (3) is a polycarbonate with a hyperbranched structure having a branching degree of 0.5 and a weight average molecular weight of 12,000.

[0104] Example 6

[0105] The difference from Example 1 is that the branching degree of the hyperbranched polymer in step (3) is 0.5.

[0106] Example 7

[0107] The difference from Example 1 is that the branching degree of the hyperbranched polymer in step (3) is 0.8.

[0108] Example 8

[0109] The difference from Example 1 is that the spraying pressure in step (3) is 100 kPa, the spraying time is 5 min, and the thickness of the functional layer 60 obtained is 20 nm.

[0110] Example 9

[0111] The difference from Example 1 is that the spraying pressure in step (3) is 20 kPa, the spraying time is 30 min, and the thickness of the functional layer 60 obtained is 100 nm.

[0112] Example 10

[0113] The difference from Example 1 is that the spraying pressure in step (3) is 120 kPa, and the thickness of the functional layer 60 obtained is 140 nm.

[0114] Comparative Example 1

[0115] The difference from Example 1 is that step (3) is omitted, and the laminated structure of the prepared perovskite solar cell does not contain the functional layer 60.

[0116] Comparative Example 2

[0117] The difference from Example 1 is that the branching degree of the hyperbranched polymer used in step (3) is 0.46.

[0118] The photovoltaic performance of the perovskite solar cell devices prepared in all the above embodiments and comparative examples of the present application was tested. The effective area of ​​the devices was 20 cm 2 ; Test conditions are as follows: spectral distribution AM1.5G, light intensity 100mW / cm 2 The JV curve was measured by forward and reverse scanning. The results are shown in Table 1 below.

[0119] Table 1

[0120]

[0121] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the above-mentioned type of hyperbranched polymer adopted in the present invention has high transparency and excellent impact strength and toughness. Using it as the material of the functional layer can not only improve the mechanical strength of the perovskite solar cell and improve its impact resistance, but also absorb the mechanical internal stress changes of the perovskite solar cell, making it suitable for flexible folding battery products; at the same time, since the hyperbranched polymer has a highly branched three-dimensional structure, it can block and absorb HI and I2 generated by the decomposition of the perovskite active material, inhibit the occurrence of subsequent chain decomposition reactions, thereby reducing the risk of lead leakage when the perovskite solar cell is damaged, and improving safety and environmental protection.

[0122] Compared with other types of hyperbranched polymers, the use of hyperbranched polymers with a branching degree in the above-mentioned specific range of the present application as the material of the functional layer is beneficial to improving the interface strength, thereby helping to improve the mechanical strength of the perovskite solar cell; it is also beneficial to better block and absorb HI and I2 generated by the decomposition of perovskite, which is beneficial to improving the safety of the perovskite solar cell.

[0123] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A perovskite solar cell, comprising a transparent conductive substrate (10), a first carrier transport layer (20), a perovskite active layer (30), a second carrier transport layer (40) and a metal electrode layer (50) stacked in sequence, characterized in that: A functional layer (60) is further provided between the first carrier transport layer (20) and the perovskite active layer (30), wherein the material of the functional layer (60) comprises a hyperbranched polymer, wherein the hyperbranched polymer is selected from one or more of the group consisting of polyamide, polyimide, polyether ester and polycarbonate having a hyperbranched structure, and the branching degree of the hyperbranched polymer is 0.5 to 0.

8.

2. The perovskite solar cell according to claim 1, characterized in that The hyperbranched polymer is a polyamide with a hyperbranched structure, with a branching degree of 0.5 to 0.8 and a weight average molecular weight of 100,000 to 150,000. Preferably, the branched ends of the polyamide with a hyperbranched structure include carboxyl groups, amide groups, and primary amine groups, and preferably, the grafted groups at the branched ends account for 2 to 5 wt% of the weight of the polyamide with a hyperbranched structure. Preferably, the hyperbranched polymer is a polyimide with a hyperbranched structure, the degree of branching is 0.55 to 0.7, the weight average molecular weight is 10000 to 13000, preferably the branched ends of the polyimide with a hyperbranched structure include amino, carboxyl, and imino groups, and preferably the grafted groups at the branched ends account for 2 to 5 wt% of the weight percentage of the polyimide with a hyperbranched structure; Preferably, the hyperbranched polymer is a polyether ester having a hyperbranched structure, the degree of branching is 0.6 to 0.8, the weight average molecular weight is 15000 to 20000, the branched ends of the polyether ester having a hyperbranched structure preferably include amino groups, carboxyl groups, and imino groups, and the weight percentage of the grafted groups at the branched ends of the polyether ester having a hyperbranched structure is preferably 1 to 4 wt%; Preferably, the hyperbranched polymer is a polycarbonate with a hyperbranched structure, whose branching degree is 0.5 to 0.8 and weight-average molecular weight is 12,000 to 18,000. Preferably, the branched ends of the polycarbonate with a hyperbranched structure include one or more of amino, carboxyl, and imino groups, and preferably, the grafted groups at the branched ends account for 2 to 5 wt% of the weight percentage of the polycarbonate with a hyperbranched structure.

3. The perovskite solar cell according to claim 1, characterized in that The thickness of the functional layer (60) is 20 to 100 nm, preferably 20 to 45 nm.

4. The perovskite solar cell according to any one of claims 1 to 3, characterized in that The first carrier transport layer (20) is a hole transport layer, and the second carrier transport layer (40) is an electron transport layer; Preferably, the thickness of the hole transport layer is 20 to 80 nm; Preferably, the thickness of the perovskite active layer (30) is 300-600 nm; Preferably, the thickness of the electron transport layer is 10 to 30 nm; Preferably, the thickness of the metal electrode layer (50) is 100-300 nm.

5. The perovskite solar cell according to claim 4, characterized in that: The perovskite solar cell further comprises an interface modification layer (70), wherein the interface modification layer (70) is arranged between the electron transport layer and the metal electrode layer (50); Preferably, the thickness of the interface modification layer (70) is 5 to 15 nm; Preferably, the material of the interface modification layer (70) is selected from bathocuproine and / or zinc oxide.

6. The perovskite solar cell according to claim 4, characterized in that: The material of the hole transport layer is selected from NiO x , one or more of the group consisting of PTAA and Spiro-OMeTAD; Preferably, the material of the perovskite active layer (30) is selected from ABX3, wherein A is CH3NH3 + NH=CHNH3 + or Cs + , B is Pb 2+ , X is Cl - or Br - ; Preferably, the material of the electron transport layer is selected from SnO2, C 60 One or more of the group consisting of and PCBM; Preferably, the material of the metal electrode layer (50) is selected from one or more of the group consisting of Au, Ag and Cu; Preferably, the transparent conductive substrate (10) is selected from ITO conductive glass, FTO conductive glass or ZITO conductive glass.

7. The perovskite solar cell according to claim 1, characterized in that: The first carrier transport layer (20) is a hole transport layer, and the thickness of the hole transport layer is 20-80 nm, and the material is NiO x , the material of the functional layer (60) is a polyimide having a hyperbranched structure, the branching degree of which is 0.55 to 0.7, and the thickness of the functional layer (60) is 25 to 35 nm; The first carrier transport layer (20) is a hole transport layer, and the thickness of the hole transport layer is 25-45 nm, and the material is NiO x The material of the functional layer (60) is polyimide with a hyperbranched structure, the branching degree of which is 0.6 to 0.7, and the thickness of the functional layer (60) is 25 to 35 nm.

8. The perovskite solar cell according to any one of claims 1 to 7, characterized in that The material of the perovskite active layer (30) is (CsPbI3) 0.05 (FAPbI3) 0.9 (MAPbBr3) 0.05 or (FAPbI3) 1-x (MAPbBr3) x .

9. A method for preparing a perovskite solar cell according to any one of claims 1 to 8, comprising sequentially preparing a first carrier transport layer (20), a perovskite active layer (30), a second carrier transport layer (40) and a metal electrode layer (50) on a surface of one side of a transparent conductive substrate (10), characterized in that: The preparation method further comprises: preparing a functional layer (60) on a surface of the first carrier transport layer (20) which is away from the transparent conductive substrate (10), wherein the preparation method of the functional layer (60) comprises: A hyperbranched polymer is mixed with a solvent to obtain a hyperbranched polymer precursor solution, the hyperbranched polymer precursor solution is coated on a surface of the first carrier transport layer (20) which is away from the transparent conductive substrate (10), and the functional layer (60) is obtained after annealing.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that: The intrinsic viscosity of the hyperbranched polymer precursor solution is 0.15 to 0.95 dL / g; Preferably, the coating is carried out by ultrasonic spraying. Preferably, during the ultrasonic spraying, the frequency of the ultrasound is 25 to 180 Hz, the pressure of the spraying is 20 to 100 kPa, the time is 5 to 30 min, and the distance between the nozzle of the ultrasonic spraying device and the surface of the side of the first carrier transport layer (20) away from the transparent conductive substrate (10) is 5 to 25 cm; preferably, the temperature of the annealing is 120 to 180° C., and the time is 0.4 to 0.8 h; Preferably, the preparation method further comprises: preparing an interface modification layer (70) on a surface of the second carrier transport layer (40) away from the perovskite active layer (30), preferably by using an atomic layer deposition method or a plasma deposition method to prepare the interface modification layer (70).

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