Perovskite solar cell and preparation method therefor and photovoltaic system

Abstract

The application provides a perovskite solar cell, a preparation method thereof and a photovoltaic system, and belongs to the technical field of solar cells.The perovskite solar cell comprises at least a conductive substrate, a modified layer and a self-assembled monolayer; the modified layer comprises a polymer containing alkaline groups and / or a polymer containing amphoteric groups; and the modified layer is combined with the self-assembled monolayer through Lewis acid-base reaction.The application sets a layer comprising a polymer containing alkaline groups and / or a polymer containing amphoteric groups between the conductive substrate and the self-assembled monolayer as a modified layer, solves the problems existing in the current hydroxylation of the surface of the conductive substrate by O3 treatment, improves the stability of the self-assembled monolayer, and improves the efficiency of the perovskite photovoltaic device.

Description

Technical Field

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

[0002] Energy is fundamental to human survival and development. With the gradual depletion of fossil fuels (oil, coal, and natural gas, etc.), renewable energy sources (solar, wind, nuclear, etc.) have become an important part of human societal development. They enrich the structure of human energy needs, meet the demands for sustainable development, and are inexhaustible, making them a current trend in green development. Among these clean energy sources, solar energy is considered the most promising and valuable new clean energy source due to its technological complexity and cost-effectiveness. Utilizing solar cells to generate electricity is a crucial practical application of solar energy.

[0003] Perovskite solar cells (PSCs) belong to the third generation of solar cells. Since their first application in photovoltaic power generation in 2009, their photoelectric conversion efficiency has increased rapidly over the past decade. Currently, the efficiency of laboratory-sized perovskite solar cells has reached 26.1%, which is less than 1% lower than that of monocrystalline silicon cells. Perovskite solar cells are expected to achieve industrialization and commercialization soon.

[0004] Self-assembled monolayers (SAMs) play a crucial role in improving the performance of perovskite solar cells. However, due to the poor thermal stability that often accompanies self-assembled monolayers, the stability of perovskite solar cells can be suppressed.

[0005] In traditional perovskite solar cell fabrication, ozone (O3) is typically used to treat the surface of the conductive substrate (such as transparent conductive glass ITO or transparent conductive glass FTO) to increase its hydrophilicity. This increases the number of hydroxyl groups (-OH) on the substrate surface, making it more hydrophilic and facilitating solution deposition of thin films. However, treating the surface of the conductive substrate with O3 presents several problems: 1. Uneven hydroxyl coverage: Uneven conductive substrate surface can lead to uneven hydroxyl distribution after ozone treatment (low hydroxyl density in depressions), resulting in uneven film formation on the conductive substrate, affecting film quality and consequently battery efficiency.

[0006] 2. Unstable surface hydroxyl groups: The conductive substrate after hydroxylation will gradually lose its activity due to the adsorption of moisture or organic matter when stored in the air for a long time. The surface hydroxyl groups will be covered or the adjacent hydroxyl groups will spontaneously condense and become inactive, which is not conducive to manufacturing.

[0007] 3. The SAM layer is prone to detachment: The hydroxyl groups on the surface of the conductive substrate are very weakly alkaline, resulting in weak spontaneous SAM anchoring. Furthermore, the anchored SAM layer is prone to hydrolysis (hydrolysis is accelerated by acids and alkalis), which affects the long-term stability of the battery.

[0008] Therefore, in this field, there is a desire to develop a method that can replace O3 treatment of conductive substrates to prepare high-performance perovskite solar cells. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite solar cell, its fabrication method, and a photovoltaic system. Existing technologies cannot adequately solve the problems associated with hydroxylation of the conductive substrate surface using O3 treatment. To address this issue, the present invention adds a modified layer between the conductive substrate and the self-assembled monolayer. The basic groups in this modified layer enrich the conductive substrate interface with amino groups and form an anchoring effect with the acidic groups of SAM, thereby improving and enhancing the performance of the perovskite optoelectronic device.

[0010] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a perovskite solar cell, the perovskite solar cell comprising at least a conductive substrate, a modified layer, and a self-assembled monolayer; The modified layer comprises a polymer containing basic groups and / or a polymer containing amphoteric groups; The modified layer is bonded to the self-assembled monolayer via a Lewis acid-base reaction.

[0011] This invention solves the problems associated with existing methods that use O3 to treat the surface of the conductive substrate for hydroxylation by placing a layer comprising a polymer containing basic groups and / or a polymer containing amphoteric groups between the conductive substrate and the self-assembled monolayer as a modification layer. Specifically, the invention provides the following: (1) The conductive substrate modified by the modified layer is rich in a large number of basic groups (e.g., rich in a large number of amino groups). The acidic groups (e.g., phosphonic acid groups) in the self-assembled monolayer can form salts with the basic groups, which increases the anchoring effect between the conductive substrate and the self-assembled monolayer, which is more conducive to film formation. Moreover, the self-assembled monolayer after the modified layer is anchored is more orderly, which is more conducive to the crystallization of the perovskite layer, thereby improving the performance of the perovskite optoelectronic device and increasing the photoelectric conversion efficiency.

[0012] (2) The modified layer fills the “depression” on the surface of the conductive substrate, making the surface of the conductive substrate smoother, and the basic groups will not fall off. The anchored self-assembled monolayer is more dense, greatly reducing the defects of the self-assembled monolayer.

[0013] (3) The present invention uses polymers containing basic groups and / or polymers containing amphoteric groups to modify the conductive substrate instead of using O3 to treat the surface of the conductive substrate for hydroxylation, which improves the anchoring rate with the self-assembled monolayer, shortens the coating time, thereby improving the spontaneity of the self-assembled monolayer self-assembly anchoring, and solves the problem that the self-assembled monolayer is easy to hydrolyze and fall off after reacting and anchoring with hydroxyl groups.

[0014] Preferably, the basic groups in the polymer containing basic groups include any one or a combination of at least two of amino, guanidine, and phosphine groups.

[0015] Preferably, the amino group includes any one or a combination of at least two of primary, secondary, and tertiary amino groups.

[0016] Preferably, the polymer containing basic groups includes any one or a combination of at least two of branched polyethyleneimine (PEI), hyperbranched polyethyleneimine, polyallylamine, and polyvinyl diphenylphosphine, and may also include other Lewis bases such as aliphatic amines, aromatic amines, and nitrogen-containing aromatic heterocycles and their derivatives. Among them, branched polyethyleneimine (PEI) and hyperbranched polyethyleneimine are also amino-rich (-NH2)-modified polymers.

[0017] Preferably, the branched polyethyleneimine has the structure shown in Formula I: Formula I; In Formula I, n is the number-average aggregation degree, and the value of n ranges from 10 to 50000, such as 10, 50, 80, 100, 200, 300, 500, 800, 1000, 2000, 3000, 5000, 6000, 8000, 10000, 20000, 30000, 40000, 50000, etc.

[0018] Preferably, the polymer containing amphoteric groups has the structure shown in Formula II: Formula II; In Formula II, X is any one or a combination of at least two of alkyl, aryl, aryl derivatives or derivatives containing a basic group; p≥0, q is the number-mean degree of aggregation.

[0019] Preferably, the polymer containing amphoteric groups includes polyarginine and / or polylysine.

[0020] Preferably, the polylysine has the following structural formula: Where n = 8 to 50000, for example 8, 10, 20, 30, 50, 80, 100, 200, 300, 500, 800, 1000, 2000, 3000, 5000, 8000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, etc.

[0021] Preferably, the perovskite solar cell includes at least the conductive substrate, the modified layer, and the self-assembled monolayer stacked sequentially.

[0022] Preferably, the conductive substrate includes any one of FTO conductive glass, ITO conductive glass, FTO conductive plastic, and ITO conductive plastic.

[0023] Preferably, the thickness of the FTO conductive glass and the FTO conductive plastic is independently 500nm~600nm, such as 500nm, 520nm, 540nm, 560nm, 580nm, 600nm, etc.

[0024] Preferably, the thickness of the ITO conductive glass and the ITO conductive plastic is independently 300nm~400nm, such as 300nm, 320nm, 340nm, 360nm, 380nm, 400nm, etc.

[0025] Preferably, the self-assembled monolayer includes a self-assembled material with acidic groups.

[0026] Preferably, the acidic group includes any one or a combination of at least two of the following: phosphonic acid group (-PO3H2), sulfonic acid group (-SO3H), boric acid group (-BO2H2), and carboxyl group (-COOH).

[0027] Preferably, the self-assembled material with acidic groups includes, but is not limited to, a carbazole core structure, and may also contain other aromatic rings and their derivatives.

[0028] Preferably, the self-assembled material with acidic groups includes (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz).

[0029] Using polymers containing basic groups as branched polyethyleneimine (PEI) Self-assembled materials with acidic groups are (Where R represents alkyl or aryl groups) Taking this as an example, the anchoring effect of the modified layer and the self-assembled monolayer is as follows: .

[0030] The specific mechanism is as follows: the phosphonic acid groups in the self-assembled monolayer react with the side-chain amino groups in PEI to form a thermally stable ammonium phosphonate salt. Since PEI is a polymer with high stability, it improves the stability of the SAM film and increases the anchoring effect between film layers, enhancing the spontaneity of the self-assembly anchoring of the film. This helps to form a stable and orderly arranged self-assembled monolayer film, thereby improving the crystallinity of perovskite, enhancing the performance of perovskite optoelectronic devices, and improving the photoelectric conversion efficiency.

[0031] Preferably, the self-assembled monolayer has a perovskite layer on the side away from the modified layer. The perovskite layer (the general formula for perovskite is ABX3) is prepared from a perovskite solution containing equimolar amounts of AX and BX2, and the solvent includes any one or a combination of at least two of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO).

[0032] Preferably, the AX includes any one or a combination of at least two of MAI, MABr, MACl, FAI, FABr, FACl, CsAI, CsBr, and CsCl.

[0033] Preferably, the BX2 includes any one or a combination of at least two of PbI2, PbBr2, PbCl2, SnI2, SnBr2, and SnCl2.

[0034] Preferably, the thickness of the perovskite layer is 0.5μm to 1μm, such as 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, etc.

[0035] Preferably, the perovskite solar cell of the present invention can be a positive structure or an inverted structure; when it is a positive structure, the perovskite solar cell includes the conductive substrate, the modified layer (which also serves as an electron transport layer), the self-assembled monolayer, the perovskite layer, the hole transport layer, and the electrode layer stacked sequentially; when it is an inverted structure, the perovskite solar cell includes the conductive substrate, the modified layer (which also serves as a hole transport layer), the self-assembled monolayer, the perovskite layer, the electron transport layer, and the electrode layer stacked sequentially.

[0036] Preferably, the hole transport layer can be made of any one of NiOx, CuI, CuSCN, PEDOT:PSS, Spiro-OMeTAD, or carbazole derivatives.

[0037] Preferably, the thickness of the hole transport layer is 10nm~200nm, such as 10nm, 20nm, 30nm, 50nm, 60nm, 80nm, 100nm, 120nm, 140nm, 150nm, 160nm, 180nm, 200nm, etc.

[0038] Preferably, the electron transport layer can be made of any one of SnO2, TiO2, ZnO, Al2O3, fullerene, fullerene derivatives (PCBM), etc.

[0039] Preferably, the thickness of the electron transport layer is 10nm~50nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, etc.

[0040] Preferably, the electrode layer is made of any one of Ag, Al, Au, IWO, and ITO.

[0041] Preferably, the thickness of the electrode layer is 100nm~200nm, such as 100nm, 120nm, 140nm, 150nm, 160nm, 180nm, 200nm, etc.

[0042] Secondly, the present invention provides a method for preparing a perovskite solar cell, the method comprising the following steps: Provide a conductive substrate; A modification layer is formed on one side of the conductive substrate to modify the conductive substrate. The modification layer includes a polymer containing basic groups and / or a polymer containing amphoteric groups. A self-assembled monolayer is formed on the modified layer, and the modified layer and the self-assembled monolayer are bonded together through a Lewis acid-base reaction.

[0043] This invention enhances the Lewis acid-base reaction by replacing hydroxyl groups with basic groups in the modified layer, thereby improving the spontaneity, robust stability, and density of the self-assembled monolayer SAM on the conductive substrate. At the same time, the modified SAM layer is more orderly arranged on the conductive substrate, which is more conducive to the subsequent crystallization of the perovskite layer, thus improving the performance of the perovskite optoelectronic device.

[0044] Preferably, a modified layer is formed on one side of the conductive substrate, specifically including: The modified layer material is mixed with a solvent to obtain a mixture; The mixture is coated onto the conductive substrate to obtain the modified layer.

[0045] Preferably, the modified layer material is mixed with a solvent to obtain a mixture, specifically including: The modified layer material is mixed with ethanol to obtain a mixture.

[0046] Preferably, the modified layer material is mixed with a solvent to obtain a mixture, specifically including: mixing the modified layer material with a solvent to obtain a mixture with a concentration of 0.01 mg / mL to 10 mg / mL (e.g., 0.01 mg / mL, 0.02 mg / mL, 0.03 mg / mL, 0.05 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.5 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, 10 mg / mL, etc.).

[0047] Preferably, the modified layer is obtained by coating the mixture onto the conductive substrate, specifically by coating the mixture onto the conductive substrate (e.g., spin coating, blade coating, or spray coating), and then annealing it at 90℃~120℃ (e.g., 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.) for 5min~20min (e.g., 5min, 10min, 15min, 20min, etc.) to obtain the modified layer.

[0048] Preferably, a self-assembled monolayer is formed on the modified layer, specifically including: A self-assembled material with acidic groups is mixed with a solvent to obtain a self-assembled material solution. The self-assembly material solution is coated onto the modified layer to obtain the self-assembly monolayer.

[0049] Preferably, the self-assembly material with acidic groups is mixed with a solvent to obtain a self-assembly material solution, specifically including: mixing the self-assembly material with acidic groups with ethanol to obtain a self-assembly material solution.

[0050] Preferably, the self-assembly material with acidic groups is mixed with a solvent to obtain a self-assembly material solution. Specifically, this includes mixing the self-assembly material with acidic groups with a solvent to obtain a self-assembly material solution with a concentration of 0.1 mg / mL to 10 mg / mL (e.g., 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.5 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, 10 mg / mL, etc.).

[0051] Preferably, the self-assembly material solution is coated onto the modified layer to obtain the self-assembly monolayer. Specifically, this includes coating the modified layer with the self-assembly material solution (e.g., spin coating, blade coating, or spray coating), and then annealing it at 90℃~120℃ (e.g., 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.) for 5min~20min (e.g., 5min, 10min, 15min, 20min, etc.) to obtain the self-assembly monolayer.

[0052] Preferably, after forming a self-assembled monolayer on the modified layer, the method further includes forming a perovskite layer on the side of the self-assembled monolayer away from the modified layer. A hole transport layer or an electron transport layer is formed on the side of the perovskite layer away from the self-assembled monolayer, and then an electrode layer is fabricated on the side of the hole transport layer or electron transport layer away from the perovskite layer to obtain the perovskite solar cell.

[0053] The flowchart of the fabrication method of the perovskite solar cell provided by this invention is as follows: Figure 1 As shown.

[0054] Thirdly, the present invention provides a photovoltaic system comprising the perovskite solar cell as described in the first aspect.

[0055] Compared with the prior art, the present invention has the following beneficial effects: This invention solves the problems of existing methods that use O3 to treat the surface of the conductive substrate for hydroxylation by setting a layer of polymer containing basic groups and / or polymer containing amphoteric groups between the conductive substrate and the self-assembled monolayer as a modification layer, thereby improving the stability of the self-assembled monolayer and increasing the efficiency of perovskite optoelectronic devices (photoelectric conversion efficiency: 19.46%~21.49%). Attached Figure Description

[0056] Figure 1 This is a flowchart illustrating the fabrication method of the perovskite solar cell provided by the present invention.

[0057] Figure 2 This is a schematic diagram of the structure of the perovskite solar cell provided in Example 1, and a diagram of the anchoring mechanism of the modified layer and the self-assembled monolayer. Among them, 1-conductive substrate, 2-modified layer, 3-self-assembled monolayer, 4-perovskite layer, 5-hole transport layer or electron transport layer, and 6-electrode layer.

[0058] Figure 3 The XRD full spectrum of the perovskite layer in the perovskite solar cells provided in Example 4 and Comparative Example 1.

[0059] Figure 4The main diffraction peaks of the perovskite in the perovskite layer of the perovskite solar cells provided in Example 4 and Comparative Example 1.

[0060] Figure 5 This is a schematic diagram illustrating the fabrication of a perovskite solar cell provided in Comparative Example 1.

[0061] Figure 6 This is a schematic diagram illustrating the fabrication of the perovskite solar cell provided in Example 2. Detailed Implementation

[0062] 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.

[0063] Example 1 In one specific implementation, see Figure 2 The diagram illustrates the structure of a perovskite solar cell and the anchoring mechanism of the modified layer and self-assembled monolayer. The perovskite solar cell includes at least a conductive substrate 1, a modified layer 2, and a self-assembled monolayer 3. The modified layer 2 comprises a polymer containing basic groups and / or a polymer containing amphoteric groups. The modified layer 2 and the self-assembled monolayer 3 are bonded through a Lewis acid-base reaction. Therefore, This invention provides a perovskite solar cell, which includes at least a conductive substrate, a modified layer, and a self-assembled monolayer; the modified layer includes a polymer containing basic groups and / or a polymer containing amphoteric groups; the modified layer and the self-assembled monolayer are bonded together via a Lewis acid-base reaction.

[0064] Furthermore, the perovskite solar cell has a perovskite layer 4, a hole transport layer or an electron transport layer 5, and an electrode layer 6 sequentially disposed on the side of the self-assembled monolayer away from the modified layer.

[0065] This specific embodiment solves the problems of existing methods that use O3 to treat the surface of the conductive substrate for hydroxylation by setting a layer of polymer containing basic groups and / or polymer containing amphoteric groups between the conductive substrate and the self-assembled monolayer as a modification layer, thereby improving the stability of the self-assembled monolayer and increasing the efficiency of perovskite optoelectronic devices.

[0066] Unless otherwise specified, the weight-average molecular weight of the branched polyethyleneimine (PEI) used in the following embodiments and comparative examples of the present invention is 800.

[0067] Example 2 This embodiment provides a perovskite solar cell, the fabrication method of which includes the following steps: (1) Provide a conductive substrate, specifically ITO conductive glass, and clean it in sequence with acetone, deionized water and ethanol, and dry it with nitrogen gas flow.

[0068] (2) The branched polyethyleneimine (PEI) was mixed with ethanol to obtain a PEI solution with a concentration of 0.5 mg / mL.

[0069] (3) Transfer the cleaned conductive substrate to a nitrogen glove box, spin coat the PEI solution onto the conductive substrate to modify the conductive substrate. The spin coating speed is 3000 rpm and the spin coating time is 30 s. Then anneal at 100℃ for 10 min to obtain the modified layer.

[0070] (4) Mix 2PACz with ethanol to obtain a 2PACz solution with a concentration of 0.5 mg / mL.

[0071] (5) Spin-coat the 2PACz solution onto the modified layer at a spin speed of 5000 rpm for 30 s, and then anneal at 100 °C for 10 min to obtain a self-assembled monolayer.

[0072] (6) Add 1.2M perovskite solution (component MA) 0.25 FA 0.75 PbI 2.92 Br 0.08 The structural formula of MA is CH3NH3 + The structural formula of FA is CH(NH2)2 + The solvent was a mixture of DMF, NMP and DMSO. The mixture was spin-coated onto the self-assembled monolayer at a speed of 3000 rpm for 30 s, and then annealed at 100 °C for 45 min to obtain the perovskite layer (PVSK).

[0073] (7) After cooling to room temperature, spin-coat the PCBM solution (solvent is chlorobenzene, concentration is 20mg / mL) onto the perovskite layer at a speed of 2000rpm.

[0074] (8) A silver electrode with a thickness of 100 nm was thermally evaporated on the perovskite layer to obtain the perovskite solar cell with a size of 0.1 cm². 2 .

[0075] Example 3 The only difference between this embodiment and Example 2 is that the concentration of the PEI solution in step (2) is 1 mg / mL.

[0076] Example 4 The only difference between this embodiment and embodiment 2 is that the concentration of the PEI solution in step (2) is 2 mg / mL.

[0077] Example 5 The only difference between this embodiment and Example 2 is that the concentration of the PEI solution in step (2) is 3 mg / mL.

[0078] Example 6 The only difference between this embodiment and Example 2 is that the branched polyethyleneimine (PEI) in step (2) is replaced with polylysine (PLL), resulting in a PLL solution with a concentration of 0.5 mg / mL. The simplified structural formula of PLL is... , n≈200.

[0079] Example 7 The only difference between this embodiment and embodiment 6 is that the concentration of the PLL solution in step (2) is 1 mg / mL.

[0080] Example 8 The only difference between this embodiment and embodiment 6 is that the concentration of the PLL solution in step (2) is 2 mg / mL.

[0081] Example 9 The only difference between this embodiment and embodiment 6 is that the concentration of the PLL solution in step (2) is 3 mg / mL.

[0082] Example 10 The only difference between this embodiment and embodiment 6 is that the concentration of the PLL solution in step (2) is 5 mg / mL.

[0083] Example 11 The only difference between this embodiment and embodiment 4 is that the annealing time is 5 minutes when preparing the self-assembled monolayer in step (5).

[0084] Example 12 The only difference between this embodiment and embodiment 4 is that the annealing time is 15 min when preparing the self-assembled monolayer in step (5).

[0085] Example 13 The only difference between this embodiment and embodiment 4 is that the annealing time is 20 min when preparing the self-assembled monolayer in step (5).

[0086] Comparative Example 1 This comparative example provides a perovskite solar cell, the fabrication method of which includes the following steps: (1) Provide a conductive substrate, specifically ITO conductive glass, and clean it in sequence with acetone, deionized water and ethanol, and dry it with nitrogen gas flow.

[0087] (2) The cleaned conductive substrate was treated with O3 plasma for 10 min.

[0088] (3) Mix 2PACz with ethanol to obtain a 2PACz solution with a concentration of 0.5 mg / mL.

[0089] (4) Spin-coat the 2PACz solution onto the conductive substrate at a spin speed of 5000 rpm for 30 s, and then anneal at 100 °C for 10 min to obtain a self-assembled monolayer.

[0090] (5) Add 1.2M perovskite solution (component MA) 0.25 FA 0.75 PbI 2.92 Br 0.08 The structural formula of MA is CH3NH3 + The structural formula of FA is CH(NH2)2 + The solvent was a mixture of DMF, NMP and DMSO. The mixture was spin-coated onto the self-assembled monolayer at a speed of 3000 rpm for 30 s, and then annealed at 100 °C for 45 min to obtain the perovskite layer (PVSK).

[0091] (6) After cooling to room temperature, spin-coat the PCBM solution (solvent is chlorobenzene, concentration is 20mg / mL) onto the perovskite layer at a speed of 2000rpm.

[0092] (7) A silver electrode with a thickness of 100 nm is thermally evaporated on the perovskite layer to obtain the perovskite solar cell with a size area of ​​0.1 cm². 2 .

[0093] Comparative Example 2 The only difference between this comparative example and comparative example 1 is that the annealing time is 5 min when preparing the self-assembled monolayer in step (4).

[0094] Comparative Example 3 The only difference between this comparative example and comparative example 1 is that the annealing time is 15 min when preparing the self-assembled monolayer in step (4).

[0095] Comparative Example 4 The only difference between this comparative example and comparative example 1 is that the annealing time in step (4) when preparing the self-assembled monolayer is 20 min.

[0096] The performance of the perovskite solar cells provided in the embodiments and comparative examples of the present invention was tested, and the performance test results are shown in Table 1.

[0097] Table 1 In Table 1, Voc is the open-circuit voltage, Jsc is the short-circuit current density, Fill Factor is the fill factor, and Efficiency is the photoelectric conversion efficiency.

[0098] As can be seen from Table 1, compared with traditional methods (excluding the modified layer), the perovskite solar cells provided by the embodiments of the present invention all exhibit higher photoelectric conversion efficiency (19.46%~21.49%), which significantly improves performance; among them, the effect is best when the PEI solution concentration is 2mg / mL (Example 4, Examples 11-13).

[0099] From the perspective of fill factor, modifying SAM with PEI or PLL significantly improves the fill factor of the cell, indicating that the anchoring effect of PEI or PLL on SAM greatly improves the charge transport efficiency and current collection effect between the two film layers, thereby significantly improving the photoelectric conversion efficiency and performance of perovskite solar cells.

[0100] Furthermore, as can be seen from Table 1, when preparing perovskite solar cells using the traditional method (excluding the modified layer), annealing for 15 minutes is required to achieve the best efficiency when preparing the self-assembled monolayer; while when preparing perovskite solar cells using the method provided by this invention, annealing for 5 minutes is sufficient to achieve near-optimal efficiency when preparing the self-assembled monolayer, thus shortening the annealing time and the SAM self-assembly anchoring time. This indicates that the modification method provided by this invention significantly improves the spontaneity of SAM self-assembly anchoring.

[0101] The perovskite layers in the perovskite solar cells provided in Example 4 and Comparative Example 1 were characterized by XRD, and the test results are as follows: Figure 3 and Figure 4 As shown, where, Figure 3 The XRD full spectrum of the perovskite layer in the perovskite solar cells provided in Example 4 and Comparative Example 1 is shown below. Figure 4 The main diffraction peaks of the perovskite in the perovskite layer of the perovskite solar cells provided in Example 4 and Comparative Example 1 show that the main XRD diffraction peak of the perovskite layer in Example 4 is significantly stronger and sharper, indicating that the SAM after PEI anchoring can promote the crystallization of perovskite and has better crystallinity than the perovskite layer in Comparative Example 1, thereby improving the performance of the perovskite solar cell.

[0102] A schematic diagram of the fabrication of the perovskite solar cell provided in Comparative Example 1 of this invention is shown below. Figure 5 As shown, O3 plasma treatment hydroxylates the surface of the conductive substrate. However, the uneven distribution of hydroxyl groups can be observed under a microscopic scale. This causes defect sites to form on the surface of the conductive substrate. At the same time, the hydroxylated conductive substrate will gradually lose its activity due to the adsorption of moisture or dust and other contaminants when stored in the air for a long time, or the adjacent hydroxyl groups will spontaneously dehydrate and condense. These factors will also cause defect sites to form on the surface of the conductive substrate, resulting in uneven SAM layer film formation.

[0103] A schematic diagram of the fabrication of the perovskite solar cell provided in Example 2 of this invention is shown below. Figure 6 As shown, after the conductive substrate is modified by preparing the modified layer, a more ordered and stable amino arrangement is formed on the surface of the conductive substrate. The arrangement of the self-assembled monolayer formed during the subsequent preparation of the self-assembled monolayer is also more ordered and dense, which is beneficial to the crystallization of the perovskite layer.

[0104] The applicant declares that the present invention is illustrated by the above embodiments to demonstrate the perovskite solar cell, its preparation method, and photovoltaic system. However, 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 perovskite solar cell, characterized in that, The perovskite solar cell comprises at least a conductive substrate, a modified layer, and a self-assembled monolayer; The modified layer comprises a polymer containing basic groups and / or a polymer containing amphoteric groups; The modified layer is bonded to the self-assembled monolayer via a Lewis acid-base reaction; The basic groups in the polymer containing basic groups include any one or a combination of at least two of amino, guanidine, and phosphine groups; The polymer containing amphoteric groups has the structure shown in Formula II: Formula II; In Formula II, X is any one or a combination of at least two of alkyl, aryl, aryl derivatives or derivatives containing a basic group; p≥0, q is the number-mean degree of aggregation.

2. The perovskite solar cell according to claim 1, characterized in that, The amino group includes any one or a combination of at least two of the primary, secondary, and tertiary amino groups.

3. The perovskite solar cell according to claim 1, characterized in that, The polymer containing basic groups includes any one or a combination of at least two of branched polyethyleneimine, hyperbranched polyethyleneimine, polyallylamine, and polyvinyl diphenylphosphine.

4. The perovskite solar cell according to claim 3, characterized in that, The branched polyethyleneimine has the structure shown in Formula I: Equation I; In Equation I, n is the number-average degree of aggregation, and the value of n ranges from 10 to 50000.

5. The perovskite solar cell according to claim 1, characterized in that, The polymers containing amphoteric groups include polyarginine and / or polylysine.

6. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell includes at least the conductive substrate, the modified layer, and the self-assembled monolayer, which are stacked sequentially. The conductive substrate includes any one of FTO conductive glass, ITO conductive glass, FTO conductive plastic, and ITO conductive plastic. The self-assembled monolayer includes a self-assembled material with acidic groups; The acidic groups include any one or a combination of at least two of the following: phosphonic acid group, sulfonic acid group, boric acid group, and carboxyl group.

7. The perovskite solar cell according to claim 6, characterized in that, The self-assembled material with acidic groups includes (2-(9H-carbazole-9-yl)ethyl)phosphonic acid.

8. The perovskite solar cell according to claim 1, characterized in that, The self-assembled monolayer has a perovskite layer on the side away from the modified layer; The perovskite solar cell comprises, in sequence, the conductive substrate, the modified layer, the self-assembled monolayer, the perovskite layer, the hole transport layer, and the electrode layer; or, the perovskite solar cell comprises, in sequence, the conductive substrate, the modified layer, the self-assembled monolayer, the perovskite layer, the electron transport layer, and the electrode layer.

9. A method for fabricating a perovskite solar cell, characterized in that, The preparation method includes the following steps: Provide a conductive substrate; A modification layer is formed on one side of the conductive substrate to modify the conductive substrate. The modification layer includes a polymer containing basic groups and / or a polymer containing amphoteric groups. A self-assembled monolayer is formed on the modified layer, and the modified layer and the self-assembled monolayer are bonded together through a Lewis acid-base reaction; Wherein, the basic groups in the polymer containing basic groups include any one or a combination of at least two of amino, guanidine, and phosphine groups; The polymer containing amphoteric groups has the structure shown in Formula II: Formula II; In Formula II, X is any one or a combination of at least two of alkyl, aryl, aryl derivatives or derivatives containing a basic group; p≥0, q is the number-mean degree of aggregation.

10. The method of claim 9, wherein, A modified layer is formed on one side of the conductive substrate, specifically including: The modified layer material is mixed with a solvent to obtain a mixture; The mixture is coated onto the conductive substrate to obtain the modified layer.

11. The method of claim 10, wherein, The modified layer material is mixed with a solvent to obtain a mixture, specifically including: The modified layer material is mixed with ethanol to obtain a mixture; And / or, mix the modified layer material with a solvent to obtain a mixture, specifically including: mixing the modified layer material with a solvent to obtain a mixture with a concentration of 0.01 mg / mL to 10 mg / mL; The modified layer is obtained by coating the mixture onto the conductive substrate, specifically by coating the mixture onto the conductive substrate and then annealing it at 90°C to 120°C for 5 min to 20 min.

12. The method of claim 9, wherein, Forming a self-assembled monolayer on the modified layer specifically includes: A self-assembled material with acidic groups is mixed with a solvent to obtain a self-assembled material solution. The self-assembly material solution is coated onto the modified layer to obtain the self-assembly monolayer.

13. The method of claim 12, wherein, A self-assembly material containing acidic groups is mixed with a solvent to obtain a self-assembly material solution. Specifically, this includes mixing the self-assembly material containing acidic groups with ethanol to obtain a self-assembly material solution. And / or, mixing a self-assembled material with acidic groups and a solvent to obtain a self-assembled material solution, specifically including: mixing a self-assembled material with acidic groups and a solvent to obtain a self-assembled material solution with a concentration of 0.1 mg / mL to 10 mg / mL; The self-assembly material solution is coated onto the modified layer to obtain the self-assembly monolayer. Specifically, this includes coating the self-assembly material solution onto the modified layer and then annealing it at 90℃~120℃ for 5min~20min to obtain the self-assembly monolayer.

14. The method of claim 9, wherein, After forming a self-assembled monolayer on the modified layer, the method further includes: forming a perovskite layer on the side of the self-assembled monolayer away from the modified layer; A hole transport layer or an electron transport layer is formed on the side of the perovskite layer away from the self-assembled monolayer, and then an electrode layer is fabricated on the side of the hole transport layer or electron transport layer away from the perovskite layer to obtain the perovskite solar cell.

15. A photovoltaic system characterized by, The photovoltaic system includes a perovskite solar cell as described in any one of claims 1-8.

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