Perovskite active layer, perovskite solar cell and preparation method thereof

Abstract

The invention belongs to the technical field of sustainable green energy, and particularly relates to a perovskite active layer, a perovskite solar cell and a preparation method thereof. According to the invention, the compound containing the alkyl chain and the functional group containing the heteroatom is introduced into the perovskite precursor solution as the additive, and the additive changes the surface energy of the perovskite precursor solution, so that the surface energy of the perovskite precursor solution is closer to the surface energy of the substrate, thereby constructing the perovskite thin film capable of fully covering the substrate. The growth of the perovskite can be regulated and controlled through the interaction between the additive and the perovskite, so that the high-quality perovskite thin film with few holes and low defect state density is obtained. The additive is introduced into the perovskite precursor solution, so that the technical problems of short circuit of a large-area device caused by the fact that a perovskite thin film of the perovskite solar cell cannot completely cover a substrate and reduction of the photoelectric property of the device caused by serious internal defects of a perovskite layer are solved.

Description

Technical Field

[0001] This invention belongs to the field of sustainable green energy technology, specifically relating to a perovskite active layer, a perovskite solar cell, and a method for preparing the same. Background Technology

[0002] Organic-inorganic hybrid perovskite materials possess many excellent photoelectric properties, such as high light absorption coefficient, long carrier lifetime, long diffusion length, tunable bandgap, and high defect tolerance, making them one of the most promising photovoltaic materials currently available. In just over a decade, the photoelectric conversion efficiency of perovskite solar cells has rapidly increased from an initial 3.8% to 26.1%, an efficiency comparable to that of polycrystalline silicon solar cells.

[0003] To further improve the performance and commercialization potential of perovskite solar cells, the quality of the perovskite layer is a key factor, specifically manifested in the perovskite's film-forming properties and internal defect state density. Currently, a large surface energy difference between the commonly used hole transport layer substrate and the perovskite precursor solution leads to poor spreadability and film formation of the perovskite precursor solution on the substrate. Consequently, the resulting perovskite film cannot completely cover the substrate, causing short circuits in large-area devices and hindering their development. Furthermore, rapid crystallization of perovskite at relatively high temperatures can introduce positively charged uncoordinated Pb. 2+ Deep traps, such as negatively charged Pb-I antisite defects, can cause recombination of photogenerated carriers, reducing the photoelectric performance of devices. They are also the main pathways for halide ion migration and the intrusion of moisture or oxygen, leading to a rapid decline in device efficiency.

[0004] To improve the coverage of perovskite films on substrates, some materials are used as interface layers to alter surface energy. To reduce the internal defect state density of perovskite films, some materials are used as perovskite additives to passivate defects and control perovskite growth. However, most reported strategies currently optimize only one specific problem. Summary of the Invention

[0005] The technical problem solved by this invention is that the low coverage of the perovskite thin film on the substrate of perovskite solar cells leads to short circuits in large-area devices, and severe internal defects in the perovskite layer lead to a decrease in the photoelectric performance of the devices.

[0006] This invention introduces compounds containing alkyl chains and heteroatoms as additives into a perovskite precursor solution. These additives alter the surface energy of the perovskite precursor solution, bringing it closer to the surface energy of the substrate, thereby constructing a perovskite film capable of fully covering the substrate. Furthermore, the interaction between the additives and the perovskite can regulate perovskite growth, resulting in a high-quality perovskite film with fewer pores and a low defect state density. In other words, by introducing additives into the perovskite precursor solution, this invention improves the coverage of the perovskite film on the substrate while simultaneously reducing the internal defect state density of the perovskite film. This solves the technical problems of short circuits in large-area devices caused by the inability of the perovskite film to fully cover the substrate in perovskite solar cells, and the reduction in photoelectric performance due to severe internal defects in the perovskite layer.

[0007] One of the objectives of this invention is to provide a perovskite active layer.

[0008] The perovskite active layer contains perovskite and additives, wherein the additives are compounds containing alkyl chains and functional groups containing heteroatoms.

[0009] The alkyl chain has 3-25 carbon atoms, preferably 5-17; the alkyl chain can be straight or branched.

[0010] The functional group containing heteroatoms is selected from at least one of amino, sulfonic acid, phosphate, and ester groups.

[0011] In the perovskite active layer, the perovskite has the chemical formula ABX3, where A is a cation, including methylamine (CH3NH3). + Formamidin (CH(NH2)) 2+ or Cs + etc.; B is a divalent cation of a group IV metal element, including Pb. 2+ Sn 2+ Or Ge 2+ etc.; X is a halogen or halogen-like monovalent anion, including F - Cl - ,Br - I - or SCN - wait.

[0012] The alkyl chain in the additive is a long alkyl chain, which is hydrophobic. The additive changes the surface energy of the perovskite precursor solution, reducing the surface energy difference between the perovskite precursor solution and the hydrophobic hole transport layer. This makes it easier for the perovskite precursor solution to spread on the hydrophobic substrate (i.e., the film-forming properties of the perovskite precursor solution are improved). The coverage of the perovskite film on the substrate is increased, thereby improving the success rate and repeatability of large-area device fabrication.

[0013] The additive can passivate uncoordinated Pb in the perovskite precursor solution through the coordination of functional groups containing heteroatoms (i.e., the zwitterionic portion of the additive can coordinate with lead iodide), and can also passivate negatively charged defects through electrostatic interaction, thereby delaying perovskite growth and facilitating the acquisition of high-quality perovskite films with fewer pores, larger grain size, and lower internal defect state density.

[0014] In addition, the hydrogen bonds between the additive and the perovskite (such as O in the additive and NH on formamidinium) can enhance the structural stability of the perovskite, prevent the intrusion of water and oxygen to a certain extent, and improve the humidity stability of the device.

[0015] As a preferred embodiment, the additive is selected from at least one of sulfonic acid amino compounds and phosphate ester compounds.

[0016] Soybean lecithin is a glycerol ester containing a phosphate group. Sulfonate betaine, also known as ammonium alkyl sulfonyl lactone, is similar to alkyl betaine as a trialkylammonium inner salt compound, except that the alkyl carboxylic acid in carboxylic betaine is replaced by an alkyl sulfonic acid, hence the name (alkyl)sulfonate betaine. The coordination between the lone pair electrons and Pb vacancies on soybean lecithin and sulfonate betaine passivates deep-level defects in perovskite, while simultaneously controlling and delaying perovskite growth, ultimately resulting in larger perovskite grain size, reduced porosity, and a decrease in defect states. The O atoms on soybean lecithin and sulfonate betaine form hydrogen bonds with the NH atoms on the formamidinium in perovskite, stabilizing the perovskite structure, reducing water and oxygen intrusion pathways, and inhibiting halogen migration, thereby improving device stability. Experiments have also demonstrated that soybean lecithin and sulfonate betaine, as additives to perovskite precursor solutions, both achieve excellent results. Therefore, the additive, as a preferred embodiment, is selected from at least one of soybean lecithin and sulfonate betaine.

[0017] The content of the additive in the perovskite active layer can be a conventional content in the art. Preferably, the additive accounts for 0.01–0.5% of the perovskite active layer by mass, more preferably 0.02–0.2%.

[0018] The second objective of this invention is to provide a method for preparing the perovskite active layer as described in the first objective of the invention, comprising: spin-coating and annealing a perovskite precursor solution containing additives to obtain the perovskite active layer.

[0019] The perovskite precursor solution is any existing perovskite precursor solution used in the art for preparing perovskite active layers. Preferably, the perovskite precursor solution is obtained by dissolving components including lead halides and amine halides in a solvent.

[0020] The method for preparing the perovskite active layer specifically includes the following steps:

[0021] Step 1) Dissolve lead halide and additives in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide to obtain perovskite precursor solution 1;

[0022] Step 2) Dissolve the haloamine in isopropanol to obtain perovskite precursor solution 2;

[0023] Step 3) Spin-coating perovskite precursor solution 1 and perovskite precursor solution 2 sequentially;

[0024] Step 4) Annealing treatment to obtain the perovskite active layer.

[0025] Specifically, in the above-mentioned method for preparing the perovskite active layer, in step 1):

[0026] By volume percentage, dimethyl sulfoxide accounts for 1 to 40% of the total volume of the N,N-dimethylformamide and dimethyl sulfoxide mixed solvent, preferably 5 to 20%;

[0027] The lead halide mentioned is lead iodide; preferably, the amount of lead iodide used is 500.5-800.5 mg per 1 mL of mixed solvent, more preferably 590.5-710.5 mg;

[0028] Based on 1 mL of the mixed solvent, the amount of the additive is 0.05–5 mg, preferably 0.1–2 mg.

[0029] Specifically, in the above-mentioned method for preparing the perovskite active layer, in step 2):

[0030] The haloamines mentioned herein include formamidine, chloromethylamine, and bromomethylamine; preferably, based on 1 mL of isopropanol: the amount of formamidine is 40-150 mg, more preferably 70-120 mg; the amount of chloromethylamine is 2-10 mg, more preferably 4-8 mg; and the amount of bromomethylamine is 2-10 mg, more preferably 4-8 mg.

[0031] Specifically, in the above-mentioned method for preparing the perovskite active layer, the spin coating speed in step 3) is 1000-6000 rpm, preferably 2000-5000 rpm.

[0032] Specifically, in the above-mentioned method for preparing the perovskite active layer, the annealing treatment in step 4) can be achieved using annealing conditions commonly used in the art; preferably, the annealing conditions are: annealing temperature 50-150℃, preferably 70-100℃; annealing time 3-30min, preferably 5-20min.

[0033] The third objective of this invention is to provide a perovskite solar cell, comprising, in sequence: a conductive glass substrate, a hole transport layer, a perovskite active layer, an electron transport layer, an electron buffer layer, and a metal electrode; wherein the perovskite active layer is the perovskite active layer described in the first objective of the invention or the perovskite active layer obtained by the preparation method described in the second objective of the invention.

[0034] Specifically:

[0035] The conductive glass substrate is ITO glass;

[0036] The hole transport layer material is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and the thickness of the hole transport layer is 1-300 nm, preferably 5-100 nm;

[0037] The thickness of the perovskite active layer is not less than 100 nm, preferably 200–700 nm;

[0038] The electron transport layer is C 60 An electron transport layer, wherein the thickness of the electron transport layer is 10–50 nm, preferably 20–40 nm;

[0039] The electron buffer layer is copper bath, and the thickness of the buffer layer is 3-30 nm, preferably 6-9 nm;

[0040] The metal electrode is selected from at least one of gold, silver, aluminum, carbon materials and their composites, preferably a silver electrode, and the thickness of the metal electrode is 50-200 nm, preferably 80-100 nm.

[0041] The fourth objective of this invention is to provide a method for preparing the above-mentioned perovskite solar cell, comprising: cleaning the surface of a conductive glass substrate, spin-coating a hole transport layer, spin-coating a perovskite active layer, evaporating an electron transport layer, evaporating a buffer layer, and evaporating a metal electrode.

[0042] Specifically, the fabrication method of the perovskite solar cell includes the following steps:

[0043] Step 1: Clean the ITO substrate with a solvent and then dry it;

[0044] Step 2: Preparation of the precursor solution:

[0045] (a) Preparation of perovskite precursor solution 1: lead halide and additives were dissolved in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide to obtain perovskite precursor solution 1.

[0046] (b) Preparation of perovskite precursor solution 2: Dissolve haloamine in isopropanol solvent to obtain perovskite precursor solution 2;

[0047] (c) Preparation of hole transport layer solution:

[0048] Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] was dissolved in an organic solvent to obtain a hole transport layer solution;

[0049] Step 3: Preparation of the hole transport layer

[0050] In a protective gas atmosphere, a hole transport layer solution is spin-coated onto an ITO substrate to obtain an ITO / HTL thin film.

[0051] Step 4: Preparation of the perovskite active layer

[0052] In a protective gas atmosphere, perovskite precursor solution 1 and perovskite precursor solution 2 were spin-coated onto an ITO / HTL film in sequence, and after annealing, a perovskite active layer film was obtained.

[0053] Step 5: Evaporation of C 60 Electron transport layer, vapor-deposited copper bath;

[0054] Step 6: Evaporate metal electrodes.

[0055] The specific operation for cleaning the ITO substrate in step one is as follows: ultrasonically clean it twice each with detergent water, deionized water, acetone, ethanol and isopropanol in sequence; then dry it in a drying oven.

[0056] In step (a):

[0057] By volume percentage, dimethyl sulfoxide accounts for 1 to 40% of the total volume of the N,N-dimethylformamide and dimethyl sulfoxide mixed solvent, preferably 5 to 20%;

[0058] The lead halide mentioned is lead iodide. Preferably, the amount of lead iodide used is 500.5-800.5 mg per 1 mL of mixed solvent, and more preferably 590.5-710.5 mg.

[0059] In step (b):

[0060] The haloamines mentioned herein include formamidine, chloromethylamine, and methylbromomethylamine. Preferably, based on 1 mL of isopropanol: the amount of formamidine is 40-150 mg, more preferably 70-120 mg; the amount of chloromethylamine is 2-10 mg, more preferably 4-8 mg; and the amount of methylbromomethylamine is 2-10 mg, more preferably 4-8 mg.

[0061] In step (d): the concentration of the hole transport layer solution is 0.5-5 mg / mL, preferably 1-2 mg / mL; the organic solvent in the hole transport layer precursor solution is toluene.

[0062] In the above-mentioned method for preparing perovskite solar cells:

[0063] The protective gas can be a commonly used protective gas in the art, for example, selected from nitrogen;

[0064] The spin coating speed in step three is 1000-8000 rpm, preferably 3000-7000 rpm;

[0065] In step four, the spin coating speed is 1000-6000 rpm, preferably 2000-5000 rpm;

[0066] The annealing conditions in step four are: annealing temperature of 50-150℃ and annealing time of 3-30 min; preferably, the annealing temperature is 70-100℃ and the annealing time is 5-20 min.

[0067] The vapor deposition conditions in step five are that the vapor deposition chamber pressure is maintained at 3 × 10⁻⁶. -4 Below Pa, evaporation rate;

[0068] The vapor deposition conditions in step six are that the vapor deposition chamber pressure is maintained at 3 × 10⁻⁶. -4 Below Pa, Evaporation rate.

[0069] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0070] In this invention, the additive modulates the surface energy of the precursor solution, enabling the precursor solution to spread smoothly on the substrate, thereby improving the film-forming properties and coverage of the perovskite film and laying the foundation for the fabrication of large-area devices.

[0071] In this invention, the additive can passivate Pb-I antisite defects or uncoordinated Pb. 2+ This invention reduces the defect state density of the thin film. The perovskite thin film containing additives prepared in this invention has a larger grain size, lower defect state density, and fewer grain boundaries, which reduces the pathways for water and oxygen intrusion and inhibits the pathways for halogen migration. Therefore, the perovskite is not easily decomposed; correspondingly, the photoelectric conversion efficiency of the perovskite solar cell is significantly improved, the hysteresis effect is effectively suppressed, and the humidity stability of the device is significantly improved.

[0072] This invention improves both the film-forming properties and film quality of perovskite films by introducing additives into the perovskite precursor solution, thus simultaneously solving two problems: "the inability of the perovskite film to completely cover the substrate in perovskite solar cells, leading to short circuits in large-area devices, and severe internal defects in the perovskite layer, resulting in reduced photoelectric performance of the devices." This invention provides a reliable and effective method for further improving film quality, thereby enhancing the photoelectric conversion efficiency and stability of corresponding solar cells, and for fabricating high-quality perovskite films and large-area devices.

[0073] Compared with traditional additive engineering and interface engineering, the method proposed in this invention greatly simplifies the preparation process of perovskite thin films. The perovskite thin films prepared by this method have significantly improved coverage, increased grain size, significantly reduced porosity, effectively passivated Pb-I antisite defects and lead vacancy defects, improved separation and transport of photogenerated carriers, and correspondingly significantly improved photoelectric conversion efficiency and stability of perovskite solar cells. Attached Figure Description

[0074] Figure 1a Image showing the contact angle of the lead iodide precursor solution on the substrate in Comparative Example 1;

[0075] Figure 1b A photograph of the perovskite thin film prepared in Comparative Example 1;

[0076] Figure 1c This is a contact angle image of the lead iodide precursor solution on the substrate in Example 1;

[0077] Figure 1d A photograph of the perovskite thin film prepared in Example 1;

[0078] Figure 2a This is a scanning electron microscope image of the perovskite thin film prepared in Comparative Example 1;

[0079] Figure 2b This is a scanning electron microscope image of the perovskite thin film prepared in Example 1;

[0080] Figure 3 These are schematic diagrams of the perovskite solar cells prepared in Examples 1-4 of this invention;

[0081] Figure 4 These are voltage-current density curves of the perovskite solar cell devices obtained in Example 1 and Comparative Example 1 under the same conditions;

[0082] Figure 5 The voltage-current density curves of the perovskite solar cell devices obtained in Example 2 and Comparative Example 1 under the same conditions are shown.

[0083] Figure 6This is a voltage-current density curve of the large-area perovskite solar cell device obtained in Example 3;

[0084] Figure 7 The voltage-current density curve of the perovskite solar cell device obtained in Example 4 is shown.

[0085] Figure 8 The graph shows the stability of the photoelectric conversion efficiency of the perovskite solar cells obtained in Example 1 and Comparative Example 1 over time (in air with a relative humidity of 40% to 50%). Detailed Implementation

[0086] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0087] The testing instruments used in the embodiments and related tests are as follows:

[0088] The contact angle was obtained using a Shanghai Zhongchen JC2000D6 contact angle measuring instrument.

[0089] Scanning electron microscope (SEM) images were obtained using a Hitachi SU8010 scanning electron microscope.

[0090] The JV curves of the perovskite solar cells were recorded using a Keithley 2400 (Keithley Instruments, USA).

[0091] The thickness of each layer was measured using a spectroscopic ellipsometry (M-200V).

[0092] Unless otherwise stated, all solvents and materials used in the examples and comparative examples are commercially available and require no further purification before use.

[0093] ITO (10Ωsq) -1 Purchased from Youxuan Technology Co., Ltd.

[0094] Lead iodide (PbI2), poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA), formamidinium iodide (FAI), methylammonium bromide (MABr), and methylammonium chloride (MACl) were purchased from Xi'an Yuri Solar Energy Technology Co., Ltd.

[0095] Soy lecithin (SL) was purchased from Saen Chemical Technology (Shanghai) Co., Ltd.

[0096] 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt (SBMA) was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0097] C 60 Obtained from Suzhou Dade Carbon Nanotechnology Co., Ltd.

[0098] N,N-Dimethylformamide (DMF, anhydrous, 99.8%), isopropanol (IPA, anhydrous, 99.8%), toluene (anhydrous, 99.8%), and dimethyl sulfoxide (DMSO, anhydrous, 99.8%) were obtained from J&K Company.

[0099] In the following embodiments and comparative examples, the effective area of ​​the device refers to the actual area of ​​the device receiving simulated sunlight; the effective area can be fixed by a mask.

[0100] Example 1

[0101] The effective area of ​​the fabricated device is 0.1 cm². 2 The perovskite solar cell. Its fabrication process is as follows:

[0102] Preparation of perovskite precursor solution:

[0103] First, weigh 299.6 mg of lead iodide and dissolve it in 500 μL of a mixed solvent of DMF and DMSO with a volume ratio of 9:1. Then, add 0.1 mg of soybean lecithin and stir at 70°C until completely dissolved to obtain a lead iodide precursor solution.

[0104] Weigh out 30 mg FAI (formamidine iodocarboxylate), 3 mg MABr (methylbromomethylamine), and 3 mg MACl (methylchloromethylamine), and dissolve them in 500 μL of isopropanol to obtain a haloamine solution. Before use, filter the haloamine solution through a 0.45 μm PTFE filter.

[0105] Preparation of hole transport layer solution:

[0106] Hole transport material poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was dissolved in toluene to prepare a PTAA solution with a concentration of 2 mg / mL. The prepared PTAA solution was then stirred on a room temperature magnetic stirrer for more than 2 hours.

[0107] Fabrication of perovskite solar cells:

[0108] The ITO glass was ultrasonically cleaned sequentially in a detergent solution, deionized water, acetone, and isopropanol for 15 minutes each. After ultrasonic cleaning, it was dried with nitrogen gas and finally placed in an oven to dry.

[0109] A 40 μL PTAA solution was spin-coated onto an ITO substrate using a spin-coating method at a speed of 5000 rpm for 30 s to obtain a hole transport layer with a thickness of 50 nm.

[0110] On the hole transport layer, 40 μL of hot lead iodide precursor solution was first spin-coated at 4000 rpm for 20 s, followed by 40 μL of amine halide solution at 4000 rpm for 30 s. After spin-coating, the sample was annealed at 140℃ for 15 min to obtain a sample with a black perovskite film (perovskite active layer). The thickness of the perovskite active layer of the sample was 550 nm.

[0111] The sample was then transferred to a vacuum evaporation apparatus, where it was deposited at a temperature below 3 × 10⁻⁶. -4 Under a vacuum of Pa, Electron transport layers C with a thickness of approximately 20 nm are deposited sequentially at a rate of [missing information]. 60 And an 8nm buffer layer of copper bath (BCP), then below 3×10 -4 Under a vacuum of Pa, Ag electrodes with a thickness of approximately 100 nm were deposited sequentially at a certain rate to obtain perovskite solar cells.

[0112] The perovskite solar cell fabricated in this embodiment has the following device structure: ITO / PTAA / Perovskite / C 60 / BCP / Ag, such as Figure 3 As shown. Figure 3 Perovskite is the active layer of the perovskite.

[0113] Example 2

[0114] The effective area of ​​the fabricated device is 0.1 cm². 2 The perovskite solar cell. Its fabrication process is as follows:

[0115] Preparation of perovskite precursor solution:

[0116] First, weigh 299.6 mg of lead iodide and dissolve it in 500 μL of a mixed solvent of DMF and DMSO with a volume ratio of 9:1. Then, add 0.2 mg of soybean lecithin and stir at 70°C until completely dissolved to obtain a lead iodide precursor solution.

[0117] Weigh out 30 mg FAI, 3 mg MABr, and 3 mg MACl, and dissolve them in 500 μL of isopropanol to obtain a haloamine solution. Before use, filter the haloamine solution through a 0.45 μm PTFE filter.

[0118] Preparation of hole transport layer solution:

[0119] PTAA was dissolved in toluene to prepare a PTAA solution with a concentration of 2 mg / mL. The prepared PTAA solution was then stirred on a magnetic stirrer at room temperature for at least 12 hours.

[0120] Fabrication of perovskite solar cells:

[0121] The ITO glass was ultrasonically cleaned sequentially in a detergent solution, deionized water, acetone, and isopropanol for 15 minutes each. After ultrasonic cleaning, it was dried with nitrogen gas and finally placed in an oven to dry.

[0122] A 40 μL PTAA solution was spin-coated onto an ITO substrate using a spin-coating method at a speed of 5000 rpm for 30 s to obtain a hole transport layer with a thickness of 45 nm.

[0123] On the hole transport layer, 40 μL of hot lead iodide precursor solution was first spin-coated at 4000 rpm for 20 s, followed by 40 μL of amine halide solution at 4000 rpm for 30 s. After spin-coating, the sample was annealed at 140℃ for 15 min to obtain a sample with a black perovskite film (perovskite active layer). The thickness of the perovskite active layer of the sample was 560 nm.

[0124] The sample was then transferred to a vacuum evaporation apparatus, where it was deposited at a temperature below 3 × 10⁻⁶. -4 Under a vacuum of Pa, Electron transport layers C with a thickness of approximately 20 nm are deposited sequentially at a rate of [missing information]. 60 And an 8nm buffer layer of copper bath (BCP), then below 3×10 -4 Under a vacuum of Pa, Ag electrodes with a thickness of approximately 100 nm were deposited sequentially at a certain rate to obtain perovskite solar cells.

[0125] The perovskite solar cell fabricated in this embodiment has the following device structure: ITO / PTAA / Perovskite / C 60 / BCP / Ag, such as Figure 3 As shown. Figure 3 Perovskite is the active layer of the perovskite.

[0126] Example 3

[0127] The effective area of ​​the fabricated device is 1.1 cm². 2 The perovskite solar cell. Its fabrication process is as follows:

[0128] Preparation of perovskite precursor solution:

[0129] First, weigh 299.6 mg of lead iodide and dissolve it in 500 μL of a mixed solvent of DMF and DMSO with a volume ratio of 9:1. Then, add 0.1 mg of soybean lecithin and stir at 70°C until completely dissolved to obtain a lead iodide precursor solution.

[0130] Weigh out 30 mg FAI, 3 mg MABr, and 3 mg MACl, and dissolve them in 500 μL of isopropanol to obtain a haloamine solution. Before use, filter the haloamine solution through a 0.45 μm PTFE filter.

[0131] Preparation of hole transport layer solution:

[0132] Hole transport material PTAA was dissolved in toluene to prepare a solution with a concentration of 2 mg / mL. The prepared PTAA solution was then stirred on a room temperature magnetic stirrer for more than 2 hours.

[0133] Fabrication of perovskite solar cells:

[0134] The ITO glass was ultrasonically cleaned sequentially in a detergent solution, deionized water, acetone, and isopropanol for 15 minutes each. After ultrasonic cleaning, it was dried with nitrogen gas and finally placed in an oven to dry.

[0135] A 40 μL PTAA solution was spin-coated onto an ITO substrate using a spin-coating method at a speed of 5000 rpm for 30 s to obtain a hole transport layer with a thickness of 45 nm.

[0136] On the hole transport layer, 40 μL of hot lead iodide precursor solution was first spin-coated at 4000 rpm for 20 s, followed by 40 μL of amine halide solution at 4000 rpm for 30 s. After spin-coating, the sample was annealed at 140℃ for 15 min to obtain a sample with a black perovskite film (perovskite active layer). The thickness of the perovskite active layer of the sample was 550 nm.

[0137] The sample was then transferred to a vacuum evaporation apparatus, where it was deposited at a temperature below 3 × 10⁻⁶. -4 Under a vacuum of Pa, Electron transport layers C with a thickness of approximately 20 nm are deposited sequentially at a rate of [missing information]. 60 And an 8nm buffer layer of copper bath (BCP), then below 3×10 -4 Under a vacuum of Pa, Ag electrodes with a thickness of approximately 100 nm were deposited sequentially at a certain rate to obtain perovskite solar cells.

[0138] The perovskite solar cell fabricated in this embodiment has the following device structure: ITO / PTAA / Perovskite / C 60 / BCP / Ag, such as Figure 3 As shown. Figure 3 Perovskite is the active layer of the perovskite.

[0139] Example 4

[0140] The effective area of ​​the fabricated device is 0.1 cm². 2 The perovskite solar cell. Its fabrication process is as follows:

[0141] Preparation of perovskite precursor solution:

[0142] First, 299.6 mg of lead iodide was weighed and dissolved in 500 μL of a mixed solvent of DMF and DMSO with a volume ratio of 9:1. Then, 0.1 mg of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt (SBMA) was added and stirred at 70 °C until completely dissolved to obtain a lead iodide precursor solution.

[0143] Weigh out 30 mg FAI, 3 mg MABr, and 3 mg MACl, and dissolve them in 500 μL of isopropanol to obtain a haloamine solution. Before use, filter the haloamine solution through a 0.45 μm PTFE filter.

[0144] Preparation of hole transport layer solution:

[0145] Hole transport material PTAA was dissolved in toluene to prepare a solution with a concentration of 2 mg / mL. The prepared PTAA solution was then stirred on a room temperature magnetic stirrer for more than 2 hours.

[0146] Fabrication of perovskite solar cells:

[0147] The ITO glass was ultrasonically cleaned sequentially in a detergent solution, deionized water, acetone, and isopropanol for 15 minutes each. After ultrasonic cleaning, it was dried with nitrogen gas and finally placed in an oven to dry.

[0148] A 40 μL PTAA solution was spin-coated onto an ITO substrate using a spin-coating method at a speed of 5000 rpm for 30 s to obtain a hole transport layer with a thickness of 50 nm.

[0149] On the hole transport layer, 40 μL of hot lead iodide precursor solution was first spin-coated at 4000 rpm for 20 s, followed by 40 μL of amine halide solution at 4000 rpm for 30 s. After spin-coating, the sample was annealed at 140℃ for 15 min to obtain a sample with a black perovskite film (perovskite active layer). The thickness of the perovskite active layer of the sample was 530 nm.

[0150] The sample was then transferred to a vacuum evaporation apparatus, where it was deposited at a temperature below 3 × 10⁻⁶. -4 Under a vacuum of Pa, Electron transport layers C with a thickness of approximately 20 nm are deposited sequentially at a rate of [missing information]. 60 And an 8nm buffer layer of copper bath (BCP), then below 3×10 -4 Under a vacuum of Pa, Ag electrodes with a thickness of approximately 100 nm were sequentially deposited at a specific rate, resulting in a perovskite solar cell. The effective area of ​​the perovskite solar cell was 0.1 cm². 2 .

[0151] The perovskite solar cell fabricated in this embodiment has the following device structure: ITO / PTAA / Perovskite / C 60 / BCP / Ag, such as Figure 3 As shown. Figure 3 Perovskite is the active layer of the perovskite.

[0152] Comparative Example 1

[0153] The effective area of ​​the fabricated device is 0.1 cm². 2 The perovskite solar cell. Its fabrication process is as follows:

[0154] Preparation of perovskite precursor solution:

[0155] First, 299.6 mg of lead iodide was weighed and dissolved in 500 μL of a mixed solvent of DMF and DMSO with a volume ratio of 9:1. The solution was stirred at 70 °C until completely dissolved to obtain a lead iodide precursor solution.

[0156] Weigh out 30 mg FAI, 3 mg MAI, and 3 mg MACl, and dissolve them in 500 μL of isopropanol to obtain a haloamine solution. Before use, filter the haloamine solution through a 0.45 μm PTFE filter.

[0157] Preparation of hole transport layer solution:

[0158] PTAA was dissolved in toluene to prepare a PTAA solution with a concentration of 2 mg / mL. The prepared PTAA solution was then stirred on a room temperature magnetic stirrer for more than 2 hours.

[0159] Fabrication of perovskite solar cells:

[0160] The ITO glass was ultrasonically cleaned sequentially in a detergent solution, deionized water, acetone, and isopropanol for 15 minutes each. After ultrasonic cleaning, it was dried with nitrogen gas and finally placed in an oven to dry.

[0161] A 40 μL PTAA solution was spin-coated onto an ITO substrate using a spin-coating method at a speed of 5000 rpm for 30 s to obtain a hole transport layer with a thickness of 50 nm.

[0162] On the hole transport layer, 40 μL of hot lead iodide precursor solution was first spin-coated at 4000 rpm for 20 s, followed by 40 μL of amine halide solution at 4000 rpm for 30 s. After spin-coating, the sample was annealed at 140℃ for 15 min to obtain a sample with a black perovskite film (perovskite active layer). The thickness of the perovskite active layer of the sample was 520 nm.

[0163] The sample was then transferred to a vacuum evaporation apparatus, where it was deposited at a temperature below 3 × 10⁻⁶. -4 Under a vacuum of Pa, Electron transport layers C with a thickness of approximately 20 nm are deposited sequentially at a rate of [missing information]. 60 And an 8nm buffer layer of copper bath (BCP), then below 3×10 -4 Under a vacuum of Pa, Ag electrodes with a thickness of approximately 100 nm were deposited sequentially at a certain rate to obtain perovskite solar cells.

[0164] The device structure of the perovskite solar cell fabricated in this comparative example is: ITO / PTAA / Perovskite / C 60 / BCP / Ag.

[0165] Related tests

[0166] I. Measuring the contact angle

[0167] The hole transport layer and lead iodide precursor solution were obtained using the method in Example 1; the contact angle of the lead iodide precursor solution on the hole transport layer was measured using a contact angle meter; the measurement results are as follows. Figure 1c As shown. A photograph of the black perovskite film (perovskite active layer) prepared in Example 1, obtained using a mobile phone camera, is shown below. Figure 1d As shown.

[0168] The hole transport layer and lead iodide precursor solution were obtained using the method in Comparative Example 1; the contact angle of the lead iodide precursor solution on the hole transport layer was measured using a contact angle meter; the measurement results are as follows. Figure 1a As shown. A photograph of the black perovskite film (perovskite active layer) prepared in Comparative Example 1, obtained using a mobile phone camera, is shown. Figure 1b As shown.

[0169] Figure 1a and Figure 1c The precursor in this context refers to the lead iodide precursor fluid droplet. Figure 1band Figure 1d The black area is perovskite, and the gray area is the background color (the part of the perovskite that is not covered).

[0170] Figure 1c The contact angle is 44±3°. Figure 1a The contact angle is 66±4°. Figure 1c The contact angle in is much smaller than Figure 1c The contact angle, specifically, the contact angle of lead iodide precursor liquid droplets with additives on ITO / PTAA is smaller.

[0171] Figure 1d The coverage of the perovskite film in it is higher than Figure 1b The coverage of perovskite films in the film.

[0172] Compare Figure 1a , Figure 1b , Figure 1c , Figure 1d It can be concluded that the introduction of additives makes the surface energy of the perovskite precursor solution closer to PTAA, thereby promoting the spreading of the perovskite precursor solution, improving the film-forming properties of the perovskite precursor solution, and resulting in a higher coverage of the formed perovskite film.

[0173] II. Microstructure of Perovskite Thin Films

[0174] The samples with attached black perovskite films (perovskite active layers) prepared in Comparative Example 1 and Example 1 were scanned using a scanning electron microscope to obtain the following results: Figure 2a , Figure 2b The image shown is a scanning electron microscope (SEM) image.

[0175] from Figure 2a , Figure 2b As can be seen, the perovskite film prepared in Example 1 has larger grains, smaller pores, and a lower defect state density, making the perovskite film more dense; this indicates that the additive can regulate the crystallization of perovskite, making its growth more uniform.

[0176] III. Current Density Voltage (JV) Curve Test

[0177] The perovskite solar cells prepared in Examples 1-4 and Comparative Example 1 were subjected to current density-voltage (JV) curve testing. The current density-voltage (JV) curve tests were conducted in a glove box under a nitrogen atmosphere and under AM 1.5G sunlight illumination with an intensity of 100 mW / cm². -2 The scanning speed is 10 mV / s. -1 The test results are shown below. Figure 4 , Figure 5 , Figure 6 , Figure 7 .

[0178] Figure 4 The JV curve test results are for the perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 4 The results show that, compared with Comparative Example 1, the open-circuit voltage of the device in Example 1 increased from 1.07V to 1.10V after the addition of 0.2mg / mL soybean lecithin.

[0179] Figure 5 The JV curve test results are for the perovskite solar cells prepared in Example 2 and Comparative Example 1. Figure 5 The results show that, compared with Comparative Example 1, after introducing the additive 0.4 mg / mL soybean lecithin, the open-circuit voltage of the device in Example 2 increased from 1.07 V to 1.10 V.

[0180] Figure 6 JV curve test of the large-area perovskite solar cell prepared in Example 3. Figure 6 The results show that the introduction of the additive soybean lecithin resulted in a fully covered perovskite thin film, enabling the fabrication of large-area devices with a final effective area of ​​1.1 cm². 2 The device has an open-circuit voltage of 1.10V and a short-circuit current density of 22.02mA / cm². -2 The fill factor was 75.9%, and the final device power conversion efficiency was 18.39%. However, using the method in Comparative Example 1, due to the lack of additives, the perovskite film could not completely cover the substrate, making it impossible to fabricate large-area devices.

[0181] Figure 7 JV curve test of the perovskite solar cell prepared in Example 4. Figure 7 The results show that, compared with Comparative Example 1, the open-circuit voltage of the device in Example 4 increased from 1.07V to 1.10V after the addition of 0.2mg / mL of betaine sulfonate.

[0182] according to Figure 4 , Figure 5 , Figure 7 The fill factor and power conversion efficiency of the perovskite solar cells prepared in Examples 1, 2, 4 and Comparative Example 1 were calculated; the results are shown in Table 1.

[0183] The fill factor is equal to the ratio of the product of the current density and voltage at the maximum power output point to the product of the open-circuit voltage and short-circuit current density.

[0184] Power conversion efficiency (PCE) is the ratio of a solar cell's output power to its incident light power. The specific calculation method is as follows: PCE = Open-circuit voltage * Short-circuit current density * Fill factor / Incident light power. The incident light power is set to one solar radiation, i.e., 100 mW / cm². 2The intensity of the incident light was calibrated using a standard silicon cell, specifically the SRC2020 model from Guangyan Technology Co., Ltd.

[0185] Table 1

[0186]

[0187] Table 1 shows that, compared to Comparative Example 1, after introducing soybean lecithin or betaine sulfonate, the open-circuit voltage of devices with the same effective area in Examples 1, 2, and 4 increased from 1.07V to 1.10V, the fill factor increased from 73.3% to 80.1-81.0%, and the final device efficiency increased from 19.52% to 21.66-22.17%. This indicates that the introduction of the additive soybean lecithin or betaine sulfonate can passivate defects in the perovskite layer, reduce the defect state density, effectively suppress nonradiative recombination, reduce voltage loss, and thus improve the power conversion efficiency of the device.

[0188] IV. Stability Testing

[0189] The perovskite solar cells prepared in Example 1 and Comparative Example 1 were placed in an air environment with a relative humidity of 40%–50% for different periods of time (placement time), and JV curve tests were performed. The power conversion efficiency (PCE) was then calculated, and a PCE-time curve was plotted to obtain a comparison chart of device stability in an air environment with a relative humidity of 40%–50%. Figure 8 As shown.

[0190] Figure 8 The results show that Example 1 retained 78% of its initial efficiency after 600 hours of storage in humid air, while Comparative Example 1 only retained 44% of its photoelectric conversion efficiency after 600 hours of storage in humid air. This demonstrates that the introduction of the additive soybean lecithin improved the quality of the perovskite film, to some extent preventing the intrusion of water and oxygen, and improving the humidity stability of the device.

[0191] The above description is merely a preferred embodiment of the present invention, and the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A perovskite active layer comprising perovskite and additives, characterized in that, The additive is a compound containing an alkyl chain and a functional group containing heteroatoms; The alkyl chain has 3-25 carbon atoms, preferably 5-17; The functional group containing heteroatoms is selected from at least one of amino, sulfonic acid, phosphate, and ester groups.

2. The perovskite active layer as described in claim 1, characterized in that, The additive is selected from at least one of sulfonic acid amino compounds and phosphate ester compounds, preferably from at least one of soybean lecithin and sulfonic acid betaine.

3. The perovskite active layer as described in claim 1, characterized in that, The additive accounts for 0.01 to 0.5% of the perovskite active layer by mass percentage, preferably 0.02 to 0.2%.

4. A method for preparing a perovskite active layer as described in claim 1, 2, or 3, characterized in that... The method includes: spin-coating and annealing a perovskite precursor solution containing the additive to obtain the perovskite active layer.

5. The preparation method according to claim 4, characterized in that... The method includes: Step 1) Dissolve lead halide and additives in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide to obtain perovskite precursor solution 1; Step 2) Dissolve the haloamine in isopropanol to obtain perovskite precursor solution 2; Step 3) Spin-coating perovskite precursor solution 1 and perovskite precursor solution 2 sequentially; Step 4) Annealing treatment to obtain the perovskite active layer.

6. The preparation method according to claim 5, characterized in that, In step 1), The lead halide is lead iodide; preferably, based on 1 mL of mixed solvent, the amount of lead iodide used is 500.5–800.5 mg, more preferably 590.5–710.5 mg; or / and, By volume percentage, dimethyl sulfoxide accounts for 1 to 40% of the total volume of the N,N-dimethylformamide and dimethyl sulfoxide mixed solvent, preferably 5 to 20%.

7. The preparation method according to claim 5, characterized in that, In step 2), The haloamines mentioned herein include formamidine, chloromethylamine, and bromomethylamine; preferably, based on 1 mL of isopropanol: the amount of formamidine is 40-150 mg, more preferably 70-120 mg; the amount of chloromethylamine is 2-10 mg, more preferably 4-8 mg; and the amount of bromomethylamine is 2-10 mg, more preferably 4-8 mg.

8. The preparation method according to claim 5, characterized in that, In step 3), the spin coating speed is 1000–6000 rpm, preferably 2000–5000 rpm; and / or, In step 4), the annealing temperature is 50–150°C, preferably 70–100°C; the annealing time is 3–30 min, preferably 5–20 min.

9. A perovskite solar cell, comprising, in sequence: The conductive glass substrate, hole transport layer, perovskite active layer, electron transport layer, electron buffer layer, and metal electrode are characterized in that: The perovskite active layer is the perovskite active layer according to any one of claims 1 to 3 or the perovskite active layer obtained by the preparation method according to any one of claims 4 to 8.

10. The perovskite solar cell according to claim 9, characterized in that, The conductive glass substrate is ITO glass; and / or, The hole transport layer material is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]; and / or, The thickness of the hole transport layer is 1–300 nm, preferably 5–100 nm; and / or, The thickness of the perovskite active layer is not less than 100 nm, preferably 200–700 nm; and / or, The electron transport layer is C 60 Electron transport layer; and / or, The thickness of the electron transport layer is 10–50 nm, preferably 20–40 nm; and / or, The electron buffer layer is copper bath; and / or, The thickness of the buffer layer is 3–30 nm, preferably 6–9 nm; and / or, The metal electrode is selected from at least one electrode made of gold, silver, aluminum, and their composites, preferably an electrode made of silver; and / or, The thickness of the metal electrode is 50–200 nm, preferably 80–100 nm.

11. A method for preparing a perovskite active layer as described in claim 9 or 10, comprising cleaning the surface of a conductive glass substrate, spin-coating a hole transport layer, spin-coating a perovskite active layer, evaporating an electron transport layer, evaporating a buffer layer, and evaporating a metal electrode.

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