Perovskite cell and preparation method and application thereof

Abstract

The present disclosure belongs to the field of photovoltaic technology, and provides a perovskite cell and a preparation method and application thereof. The perovskite cell comprises, from bottom to top, a conductive substrate, a hole transport layer, a perovskite film, a first passivation layer, a second passivation layer, an electron transport layer and an electrode; the first passivation layer and the second passivation layer are respectively composed of a first pyrimidine derivative and a second pyrimidine derivative. By introducing the double-layer passivation layer, the surface defects of the perovskite film are passivated, the carrier lifetime is prolonged, the device band structure is improved, the water vapor is blocked, the oxidation is prevented, and the efficiency and stability of the perovskite cell are effectively improved. A photovoltaic module comprising a plurality of the above perovskite cells is also disclosed. The first passivation layer of the present disclosure interacts with the defect sites of the perovskite film to form a chemical bond, thereby reducing surface recombination through chemical passivation; the second passivation layer can better block water vapor erosion and improve stability, thereby enhancing the stability and conversion efficiency of the perovskite cell.

Description

Technical Field

[0001] This disclosure relates to the field of photovoltaic technology, and in particular to a perovskite solar cell, its preparation method, and its application. Background Technology

[0002] The energy conversion efficiency of perovskite solar cells has increased from 3.8% to 26.7% in just sixteen years, demonstrating strong competitiveness. However, due to the high sensitivity of perovskite to moisture and oxygen in the air, most high-quality perovskite thin films are prepared in a strictly controlled inert environment. Such an environment can only be achieved through the use of complex air or humidity control systems, which inevitably increases the cost of manufacturing equipment and is not conducive to large-scale production. To develop more economical and stable perovskite photovoltaic devices, it is necessary to prepare high-quality perovskite thin films under atmospheric humidity conditions, especially FA (formamidinium)-based perovskite, which is more stable to photothermal conditions. In addition, interface defects are a key factor affecting the stability and efficiency of perovskite solar cells. Relying on a single molecule species may not be able to effectively solve the problems of interface recombination and stability simultaneously. Therefore, it is necessary to develop a matching passivation method to improve its stability and conversion efficiency. Summary of the Invention

[0003] This disclosure provides a perovskite solar cell, its preparation method, and its application, to at least solve the above-mentioned technical problems existing in the prior art.

[0004] According to a first aspect of this disclosure, a perovskite solar cell is provided, the perovskite solar cell comprising, from bottom to top, a conductive substrate, a hole transport layer, a perovskite thin film, a first passivation layer, a second passivation layer, an electron transport layer, and electrodes;

[0005] The first passivation layer is composed of a first pyrimidine derivative, the molecular structure of which contains a -OH group and a N atom in the heterocycle; the second passivation layer is composed of a second pyrimidine derivative, the molecular structure of which contains ≥1 S atom and ≥1 N atom; the first pyrimidine derivative and the second pyrimidine derivative are different.

[0006] Specifically, the nitrogen atom in the first pyrimidine derivative can form a strong coordination interaction with the uncoordinated lead ions exposed at the perovskite film interface, filling the vacancies of halide ions, thereby passivating the dangling bonds at the interface and stabilizing the crystal structure, thus improving the photoelectric conversion efficiency of the perovskite solar cell. The nitrogen atom in the second pyrimidine derivative contains lone pairs of electrons, and the sulfur atom contains unbonded electron pairs, classifying them as Lewis bases. The unsaturated lead ions at the perovskite film interface can accept these unbonded electron pairs, classifying them as Lewis acids. Lewis acid-base theory indicates that both nitrogen and sulfur atoms can form strong coordination interactions with the exposed lead ions at the perovskite film interface, filling the vacancies of halide ions, thereby passivating the dangling bonds at the interface and stabilizing the crystal structure. Furthermore, they can enhance the hydrophobicity of the perovskite film, better resisting moisture erosion and improving stability.

[0007] In one embodiment, the first pyrimidine derivative is selected from dihydroxypyrimidine.

[0008] In one embodiment, the second pyrimidine derivative is selected from either 2-mercaptopyrimidine or 2-thiopyrimidine.

[0009] In one embodiment, the thickness of both the first passivation layer and the second passivation layer is 3-10 nm, and the thickness of the first passivation layer is greater than the thickness of the second passivation layer.

[0010] In one embodiment, the conductive substrate is a transparent conductive substrate, selected from any one of ITO, FTO, and ZTO.

[0011] In one possible embodiment, the material of the hole transport layer (HTL) is selected from PTAA, 2PACZ, and NiO. x At least one of 4PADBC.

[0012] In one embodiment, the perovskite film is made of ABX3 type perovskite, wherein A is a metal cation or alkylammonium salt selected from Cs. + K + 、Rb + CH3NH3 + NH2CHNH2 + B is a divalent metal cation selected from Cu. 2+ Ni 2+ Co 2 + Fe 2+ Mn 2+ Cr 2+ Pd 2+ Cd 2+ 、Ge 2+ Sn 2+ Pb 2+ Eu2+ Yb 2+ X is a halide anion, selected from I - ,Br - Cl - .

[0013] In one embodiment, the material of the electron transport layer is selected from at least one of TiO2, ZnO, SnO2, and PCBM.

[0014] In one embodiment, the thickness of the electron transport layer is 20–30 nm.

[0015] In one embodiment, the material of the electrode is selected from at least one of Al, Ag, Au, Mo, and Cr.

[0016] In one embodiment, the thickness of the electrode is 80–110 nm.

[0017] According to a second aspect of this disclosure, a method for preparing a perovskite solar cell is provided, comprising the following steps:

[0018] S1: A hole transport layer and a perovskite thin film are sequentially prepared on a conductive substrate;

[0019] S2: A first passivation layer and a second passivation layer are sequentially prepared on the side of the perovskite thin film opposite to the hole transport layer; the first passivation layer is made of a first pyrimidine derivative, the molecular structure of which contains a -OH group and a N atom in the heterocycle; the second passivation layer is made of a second pyrimidine derivative, the molecular structure of which contains ≥1 S atom and ≥1 N atom; the first pyrimidine derivative and the second pyrimidine derivative are different;

[0020] S3: An electron transport layer and an electrode are sequentially fabricated on the side of the second passivation layer opposite to the first passivation layer to obtain the perovskite solar cell.

[0021] In one embodiment, step S1 involves cleaning and treating the conductive substrate with ultraviolet ozone.

[0022] Specifically, the purpose of cleaning and ultraviolet ozone (UVO) treatment of the conductive substrate is to remove organic matter from the surface of the conductive substrate and increase the wettability of the conductive substrate surface.

[0023] Specifically, in step S1, the conductive substrate is ultrasonically cleaned with cleaning agent, water, organic solvent, and detergent for 1 to 1.5 hours, followed by ultraviolet ozone treatment for 3 to 30 minutes.

[0024] Specifically, the organic solvent is selected from at least one of ethanol, acetone, and isopropanol.

[0025] Specifically, the conductive substrate is a transparent conductive substrate, selected from any one of ITO, FTO, and ZTO.

[0026] In one embodiment, step S1 involves preparing the hole transport layer using a spin coating method.

[0027] Specifically, the material of the hole transport layer is selected from PTAA, 2PACZ, and NiO. x At least one of 4PADBC.

[0028] Specifically, the concentration of the material in the hole transport layer is 1–20 mg / mL.

[0029] Specifically, in step S1, the material of the hole transport layer is coated onto the conductive substrate, spin-coated at a speed of 3000-6000 rpm for 30-45 seconds, and then annealed at 90-110°C for 10-15 minutes to obtain the hole transport layer.

[0030] In one embodiment, step S1 involves sequentially coating a perovskite precursor solution and an ammonium salt onto the side of the hole transport layer opposite to the conductive substrate using a spin coating or slot coating method, followed by annealing to form the perovskite film.

[0031] Specifically, the perovskite film is made of ABX3 type perovskite, wherein A is a metal cation or alkylammonium salt selected from Cs. + K + 、Rb + CH3NH3 + NH2CHNH2 + B is a divalent metal cation selected from Cu. 2+ Ni 2+ Co 2+ Fe 2+ Mn 2+ Cr 2+ Pd 2+ Cd 2+ 、Ge 2+ Sn 2+ Pb 2+ Eu 2+ Yb 2+ X is a halide anion, selected from I - ,Br - Cl - .

[0032] Specifically, the perovskite precursor solution comprises BX2, wherein B is a divalent metal cation selected from Cu. 2+ Ni 2+ Co 2 + Fe2+ Mn 2+ Cr 2+ Pd 2+ Cd 2+ 、Ge 2+ Sn 2+ Pb 2+ Eu 2+ Yb 2+ X is a halide anion, selected from I - ,Br - Cl - .

[0033] Specifically, the concentration of the perovskite precursor solution is 700–800 mg / mL.

[0034] Specifically, the perovskite precursor solution is prepared by dissolving BX2 in a solvent, wherein the solvent is a mixture of N,N-dimethylformamide (DMF) and N-methylpyrrolidone (NMP).

[0035] Specifically, the volume ratio of N,N-dimethylformamide to N-methylpyrrolidone is 5 to 10:1.

[0036] Specifically, the ammonium salt is a mixed solution of FAI, MASCN and NH4SCN, with concentrations of 60–100 mg / mL, 5–20 mg / mL and 3–9 mg / mL, respectively.

[0037] Specifically, when the perovskite precursor solution and the ammonium salt are coated by spin coating, the spin coating speed is 3500-4000 rpm and the time is 3-5 s.

[0038] Specifically, the annealing temperature after coating the perovskite precursor solution is 50–70°C and the time is 2–10 min; the annealing temperature after coating the ammonium salt is 130–140°C and the time is 20–60 min.

[0039] In one embodiment, step S2 involves preparing the first passivation layer and the second passivation layer by spin coating or slot coating.

[0040] In one embodiment, after applying the first passivation layer and the second passivation layer in step S2, annealing is required for both. The annealing temperature is 100-135°C and the annealing time is 5-10 minutes.

[0041] In one embodiment, the first pyrimidine derivative is selected from dihydroxypyrimidine.

[0042] In one embodiment, the second pyrimidine derivative is selected from either 2-mercaptopyrimidine or 2-thiopyrimidine.

[0043] In one embodiment, the thickness of both the first passivation layer and the second passivation layer is 3-10 nm, and the thickness of the first passivation layer is greater than the thickness of the second passivation layer.

[0044] In one embodiment, step S3 involves preparing the electron transport layer by spin coating or vapor deposition, and preparing the electrode by vapor deposition.

[0045] Specifically, the material of the electron transport layer is selected from at least one of TiO2, ZnO, SnO2, and PCBM.

[0046] Specifically, the thickness of the electron transport layer is 20–30 nm.

[0047] Specifically, the material of the electrode is selected from at least one of Al, Ag, Au, Mo, and Cr.

[0048] Specifically, the thickness of the electrode is 80–110 nm.

[0049] According to a third aspect of this disclosure, a photovoltaic module is provided, comprising a plurality of perovskite cells of the first aspect connected in series and / or in parallel.

[0050] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved:

[0051] This disclosure introduces a double passivation layer at the upper interface of a perovskite thin film. The pyrimidine derivative in the passivation layer has functional groups such as -C=O, -S=O, OH-, or -NH. The first pyrimidine derivative interacts with the defect sites of the perovskite thin film to form chemical bonds, reducing surface recombination through chemical passivation. The subsequently introduced second pyrimidine derivative enhances the hydrophobicity of the perovskite thin film, better blocking water vapor erosion and improving stability, thereby enhancing the stability and conversion efficiency of the perovskite solar cell. The corresponding photovoltaic module also exhibits enhanced photovoltaic performance and environmental stability.

[0052] This disclosure improves the existing perovskite solar cell fabrication process, finds the most suitable process conditions, realizes a method for preparing perovskite thin films in air, and develops a bilayer pyrimidine derivative as a composite passivation agent, achieving a device efficiency of up to 20.15%.

[0053] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0054] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0055] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0056] Figure 1 A schematic diagram of the structure of a perovskite solar cell according to a specific embodiment of this disclosure is shown;

[0057] Figure 2 A schematic diagram of the molecular structure of dihydroxypyrimidine in Embodiment 1 of this disclosure is shown;

[0058] Figure 3 A schematic diagram of the molecular structure of 2-mercaptopyrimidine in Example 1 of this disclosure is shown;

[0059] Figure 4 A schematic diagram of the molecular structure of 2-thiopyrimidine in Embodiment 2 of this disclosure is shown;

[0060] Figure 5 A scanning electron microscope image of the passivated perovskite thin film in Embodiment 1 of this disclosure is shown;

[0061] Figure 6 A scanning electron micrograph of the passivated perovskite film in Comparative Example 1 of this disclosure is shown;

[0062] Figure 7 A scanning electron micrograph of the perovskite thin film in Comparative Example 2 of this disclosure is shown;

[0063] Figure 8 JV curves of perovskite solar cells prepared in Examples 1 and 2 and Comparative Examples 1 to 4 of this disclosure are shown.

[0064] Figure 9 The photoelectric conversion efficiency statistics of the perovskite solar cells of Embodiment 1, Comparative Example 1 and Comparative Example 2 of this disclosure are shown.

[0065] Figure label:

[0066] 11-Conductive substrate; 12-Hole transport layer; 13-Perovskite thin film; 14-First passivation layer; 15-Second passivation layer; 16-Electron transport layer; 17-Electron electrode. Detailed Implementation

[0067] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0068] Low-oxygen, low-humidity environments are ideal for perovskite fabrication, but such environments require strict control, inevitably increasing costs significantly. To develop more economical and stable perovskite photovoltaic devices, it is necessary to develop methods for preparing high-quality perovskite thin films under ambient humidity conditions, especially for FA (methyl ether)-based perovskites which are more photothermally stable. Furthermore, interfacial defects are a key factor affecting the stability and efficiency of perovskite solar cells. Relying on a single molecule type may not effectively solve both interfacial recombination and stability problems simultaneously. Therefore, it is necessary to develop matching passivation methods to improve stability and conversion efficiency. This disclosure seeks to address the complex interfacial carrier recombination problem using combinations of different molecules, each with a different function.

[0069] This disclosure provides a perovskite solar cell, the structural schematic of which is shown below. Figure 1 As shown, the perovskite solar cell includes, from bottom to top, a conductive substrate 11, a hole transport layer 12, a perovskite thin film 13, a first passivation layer 14, a second passivation layer 15, an electron transport layer 16, and an electrode 17; wherein, the first passivation layer 14 (thickness of 3-10 nm) is composed of a first pyrimidine derivative, which is selected from dihydroxypyrimidine; the second passivation layer 15 (thickness of 3-10 nm) is composed of a second pyrimidine derivative, which is selected from either 2-mercaptopyrimidine or 2-thiopyrimidine.

[0070] The conductive substrate 11 is a transparent conductive substrate, selected from any one of ITO, FTO, and ZTO.

[0071] The hole transport layer (HTL) 12 is made of materials selected from PTAA, 2PACZ, and NiO. x At least one of 4PADBC.

[0072] The perovskite thin film 13 is made of ABX3 type perovskite, where A is a metal cation or alkylammonium salt selected from Cs. + K + 、Rb + CH3NH3 + NH2CHNH2 + B is a divalent metal cation selected from Cu. 2+ Ni 2+ Co2+ Fe 2+ Mn 2+ Cr 2+ Pd 2+ Cd 2 + 、Ge 2+ Sn 2+ Pb 2+ Eu 2+ Yb 2+ X is a halide anion, selected from I - ,Br - Cl - .

[0073] The electron transport layer 16 is made of at least one of TiO2, ZnO, SnO2, and PCBM, and its thickness is 20–30 nm.

[0074] The material of electrode 17 is selected from at least one of Al, Ag, Au, Mo, and Cr, and its thickness is 80 to 110 nm.

[0075] This disclosure, based on the high-quality perovskite thin film prepared in air for perovskite solar cells, introduces a double passivation layer (a double pyrimidine derivative). The pyrimidine derivative contains functional groups such as -C=O, -S=O, OH-, or -NH. The first introduced pyrimidine derivative interacts with defect sites to form chemical bonds, reducing surface recombination through chemical passivation. The subsequently introduced second pyrimidine derivative better resists moisture erosion, improving stability and thus enhancing the stability and conversion efficiency of the perovskite solar cell.

[0076] The following examples illustrate this in detail.

[0077] Example 1

[0078] This embodiment demonstrates the fabrication of a perovskite solar cell, and the specific process is as follows:

[0079] (1) The ITO was ultrasonically cleaned sequentially with ITO cleaner, ultrapure water, isopropanol, and detergent for 60 min; then the ITO was treated with ultraviolet ozone for 10 min. PTAA was spin-coated onto the cleaned and treated ITO at a speed of 4000 rpm for 30 s. After spin-coating, the ITO was annealed on a 100℃ hot plate for 10 min to obtain the hole transport layer.

[0080] (2) Take 700 mg / mL of PbI2 solution and dissolve it in a mixture of DMF and NMP (the volume ratio of DMF to NMP is 9:1). Spin-coat the above solution onto the hole transport layer at a speed of 3600 rpm for 3 s. After spin-coating, immerse the layer in isopropanol for 20 s and then anneal it at 60 °C for 2 min. Subsequently, spin-coat the prepared ammonium salt mixture (the concentration ratio of FAI, MASCN and NH4SCN is 90:15:5, which are 90 mg / mL, 15 mg / mL and 5 mg / mL respectively), and then anneal it in air at 135 °C for 60 min to obtain FAPbI3 perovskite film.

[0081] (3) First, a layer of dihydroxypyrimidine (its molecular structure diagram is shown in the figure) is dynamically spin-coated onto the perovskite film. Figure 2 As shown in the figure), the spin coating speed was 4000 rpm. After spin coating, it was annealed at 135℃ for 5 min to obtain the first passivation layer. Then, a layer of 2-mercaptopyrimidine (its molecular structure diagram is shown in the figure) was dynamically spin-coated onto the first passivation layer. Figure 3 As shown in the figure, the spin coating speed was 4000 rpm. After spin coating, the film was annealed at 135℃ for 5 min to obtain the second passivation layer. The perovskite film with two passivation layers was observed under a scanning electron microscope, and the results are as follows. Figure 5 As shown. Figure 5 The results show that defects at the grain boundaries of the perovskite thin film are significantly reduced, and it can effectively block water vapor erosion.

[0082] (4) An electron transport layer TiO2 with a thickness of 25 nm is deposited on the second passivation layer; and a metal electrode Al with a thickness of 100 nm is deposited on the electron transport layer TiO2.

[0083] This leads to the development of a high-efficiency perovskite solar cell.

[0084] Example 2

[0085] This embodiment demonstrates the fabrication of a perovskite solar cell, and the specific process is as follows:

[0086] (1) The ITO was ultrasonically cleaned sequentially with ITO cleaner, ultrapure water, isopropanol, and detergent for 60 min; then the ITO was treated with ultraviolet ozone for 10 min. PTAA was spin-coated onto the cleaned and treated ITO at a speed of 4000 rpm for 30 s. After spin-coating, the ITO was annealed on a 100℃ hot plate for 10 min to obtain the hole transport layer.

[0087] (2) Take 700 mg / mL PbI2 solution and dissolve it in a mixture of DMF and NMP (the volume ratio of DMF to NMP is 9:1). Spin-coat the above solution onto the hole transport layer at a speed of 3600 rpm for 3 s. After spin-coating, immerse the layer in isopropanol for 15-30 s and then anneal it at 60 °C for 2 min. Subsequently, spin-coat the prepared ammonium salt mixture (the concentration ratio of FAI, MASCN and NH4SCN is 90:15:5, which are 90 mg / mL, 15 mg / mL and 5 mg / mL respectively), and then anneal it in air at 135 °C for 60 min to obtain FAPbI3 perovskite film.

[0088] (3) A layer of dihydroxypyrimidine was first dynamically spin-coated onto the perovskite film at a spin speed of 4000 rpm. After spin-coating, the film was annealed at 135 °C for 5 min to obtain the first passivation layer. Then, a layer of 2-thiopyrimidine (its molecular structure diagram is shown in the figure) was dynamically spin-coated onto the first passivation layer. Figure 4 As shown, the spin coating speed was 4000 rpm. After spin coating, the coating was annealed at 135℃ for 5 min to obtain the second passivation layer.

[0089] (4) An electron transport layer PCBM with a thickness of 25 nm is deposited on the second passivation layer; and a metal electrode Au with a thickness of 100 nm is deposited on the electron transport layer PCBM.

[0090] This leads to the development of a high-efficiency perovskite solar cell.

[0091] Comparative Example 1

[0092] This comparative example fabricates a perovskite solar cell. The difference from Example 1 is that this comparative example only has a passivation layer. The specific process is as follows:

[0093] (1) The ITO was ultrasonically cleaned sequentially with ITO cleaner, ultrapure water, isopropanol, and detergent for 60 min; then the ITO was treated with ultraviolet ozone for 10 min. PTAA was spin-coated onto the cleaned and treated ITO at a speed of 4000 rpm for 30 s. After spin-coating, the ITO was annealed on a 100℃ hot plate for 10 min to obtain the hole transport layer.

[0094] (2) Take 700 mg / mL PbI2 solution and dissolve it in a mixture of DMF and NMP (the volume ratio of DMF to NMP is 9:1). Spin-coat the above solution onto the hole transport layer at a speed of 3600 rpm for 3 s. After spin-coating, immerse the layer in isopropanol for 15-30 s and then anneal it at 60 °C for 2 min. Subsequently, spin-coat the prepared ammonium salt mixture (the concentration ratio of FAI, MASCN and NH4SCN is 90:15:5, which are 90 mg / mL, 15 mg / mL and 5 mg / mL respectively), and then anneal it in air at 135 °C for 60 min to obtain FAPbI3 perovskite film.

[0095] (3) A layer of dihydroxypyrimidine was dynamically spin-coated onto the perovskite film at a spin speed of 4000 rpm. After spin-coating, the film was annealed at 135 °C for 5 min to obtain a passivation layer. The perovskite film with the passivation layer was observed under a scanning electron microscope, and the results are as follows: Figure 6 As shown. Figure 6 The results show that defects at the grain boundaries of the perovskite thin film are significantly reduced.

[0096] (4) An electron transport layer TiO2 with a thickness of 25 nm is deposited on the second passivation layer; and a metal electrode Al with a thickness of 100 nm is deposited on the electron transport layer TiO2.

[0097] This process yields perovskite solar cells.

[0098] Comparative Example 2

[0099] This comparative example fabricates a perovskite solar cell. The difference between this example and Example 1 is that no passivation layer was prepared in this comparative example. The remaining processes are the same as in Example 1.

[0100] The prepared perovskite thin film was observed under a scanning electron microscope, and the results are as follows: Figure 7 As shown. Figure 7 The results show that there are more defects at the grain boundaries of the perovskite thin film.

[0101] Comparative Example 3

[0102] This comparative example prepared a perovskite solar cell. The difference from Example 1 is that in this comparative example, only a 2-mercaptopyrimidine monolayer passivation layer was prepared on the perovskite thin film. The rest of the process was the same as in Example 1.

[0103] Comparative Example 4

[0104] This comparative example prepared a perovskite solar cell. The difference from Example 2 is that this comparative example only prepared a 2-thiopyrimidine monolayer passivation layer on the perovskite film. The rest of the process was the same as in Example 1.

[0105] Test case

[0106] The short-circuit current, open-circuit voltage, photoelectric conversion efficiency, and fill factor of the perovskite solar cells prepared in Examples 1, 2, and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0107] Table 1

[0108]

[0109] The JV curves of the perovskite solar cells prepared in Examples 1 and 2 and Comparative Examples 1-4 are as follows: Figure 8 As shown in Table 1 and Figure 8 The results show that the perovskite solar cells of Examples 1 and 2 have relatively large open-circuit voltages and fill factors. The perovskite solar cells of Comparative Examples 1, 3 and 4 all have only one passivation layer, and their open-circuit voltages and fill factors are significantly lower than those of Examples 1 and 2. Comparative Example 2 did not have a passivation layer, and the corresponding perovskite solar cell showed a more significant reduction in open-circuit voltage and fill factor.

[0110] In addition, the stability of the perovskite solar cells prepared in Example 1, Comparative Example 1, and Comparative Example 2 was tested, and the results are as follows: Figure 9 As shown. Figure 9 The results show that the perovskite solar cell of Example 1 (double passivation layer) has the highest photoelectric conversion efficiency at 20.15%; the photoelectric conversion efficiency of the perovskite solar cell of Comparative Example 1 (single passivation layer) is slightly lower at 19.14%; and the photoelectric conversion efficiency of the perovskite solar cell of Comparative Example 2 (no passivation layer) is the most significantly reduced at 16.00%. It is evident that the efficiency stability of the perovskite solar cell without passivation (Comparative Example 2) is poor. Compared to single passivation (Comparative Example 1), the efficiency of the perovskite solar cell with double passivation (Example 1) is the most stable. This is because the introduction of a double passivation layer passivates the surface defects of the perovskite film, prolongs the carrier lifetime, improves the band structure of the device, blocks moisture, and prevents oxidation, effectively improving the efficiency and stability of the perovskite solar cell.

[0111] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0112] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0113] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A perovskite solar cell, characterized in that, The perovskite solar cell includes, from bottom to top, a conductive substrate, a hole transport layer, a perovskite thin film, a first passivation layer, a second passivation layer, an electron transport layer, and electrodes. The first passivation layer is composed of a first pyrimidine derivative, the molecular structure of which contains a -OH group and a N atom in the heterocycle; the second passivation layer is composed of a second pyrimidine derivative, the molecular structure of which contains ≥1 S atom and ≥1 N atom; the first pyrimidine derivative and the second pyrimidine derivative are different.

2. The perovskite solar cell according to claim 1, characterized in that, The first pyrimidine derivative is selected from dihydroxypyrimidine; Preferably, the second pyrimidine derivative is selected from either 2-mercaptopyrimidine or 2-thiopyrimidine; Preferably, the thickness of both the first passivation layer and the second passivation layer is 3-10 nm, and the thickness of the first passivation layer is greater than the thickness of the second passivation layer.

3. The perovskite solar cell according to claim 1, characterized in that, The conductive substrate is a transparent conductive substrate, selected from any one of ITO, FTO, and ZTO. Preferably, the material of the hole transport layer is selected from PTAA, 2PACZ, and NiO. x At least one of 4PADBC; Preferably, the perovskite film is made of ABX3 type perovskite, wherein A is a metal cation or alkylammonium salt selected from Cs. + K + 、Rb + CH3NH3 + NH2CHNH2 + B is a divalent metal cation selected from Cu. 2+ Ni 2+ Co 2+ Fe 2+ Mn 2+ Cr 2+ Pd 2+ Cd 2+ 、Ge 2+ Sn 2+ Pb 2+ Eu 2+ Yb 2+ X is a halide anion, selected from I - ,Br - Cl - .

4. The perovskite solar cell according to claim 1, characterized in that, The electron transport layer is made of at least one of TiO2, ZnO, SnO2, and PCBM, and its thickness is 20–30 nm. Preferably, the electrode is made of at least one of Al, Ag, Au, Mo, and Cr, and has a thickness of 80–110 nm.

5. A method for preparing a perovskite solar cell, characterized in that, Includes the following steps: S1: A hole transport layer and a perovskite thin film are sequentially prepared on a conductive substrate; S2: A first passivation layer and a second passivation layer are sequentially prepared on the side of the perovskite thin film opposite to the hole transport layer; the first passivation layer is made of a first pyrimidine derivative, the molecular structure of which contains a -OH group and a N atom in the heterocycle; the second passivation layer is made of a second pyrimidine derivative, the molecular structure of which contains ≥1 S atom and ≥1 N atom; the first pyrimidine derivative and the second pyrimidine derivative are different; S3: An electron transport layer and an electrode are sequentially fabricated on the side of the second passivation layer opposite to the first passivation layer to obtain the perovskite solar cell.

6. The preparation method according to claim 5, characterized in that, Step S1 involves preparing the hole transport layer using a spin coating method.

7. The preparation method according to claim 5, characterized in that, In step S1, perovskite precursor solution and ammonium salt are sequentially coated on the side of the hole transport layer away from the conductive substrate by spin coating or slot coating, and the perovskite film is formed by annealing. Preferably, the perovskite precursor solution comprises BX2, wherein B is a divalent metal cation selected from Cu. 2+ Ni 2+ Co 2+ Fe 2 + Mn 2+ Cr 2+ Pd 2+ Cd 2+ 、Ge 2+ Sn 2+ Pb 2+ Eu 2+ Yb 2+ X is a halide anion, selected from I - ,Br - Cl - ; Preferably, the perovskite precursor solution is prepared by dissolving BX2 in a solvent, wherein the solvent is a mixture of N,N-dimethylamide and N-methylpyrrolidone; Preferably, the ammonium salt is a mixed solution of FAI, MASCN and NH4SCN.

8. The preparation method according to claim 5, characterized in that, Step S2 involves preparing the first passivation layer and the second passivation layer using either spin coating or slot coating. Preferably, after applying the first passivation layer and the second passivation layer in step S2, annealing is required for both.

9. The preparation method according to claim 5, characterized in that, Step S3 involves preparing the electron transport layer by spin coating or vapor deposition, and preparing the electrode by vapor deposition.

10. A photovoltaic module, characterized in that, The photovoltaic module includes multiple perovskite cells as described in any one of claims 1 to 4, connected in series and / or in parallel.

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