All-perovskite tandem solar cell and preparation method and application thereof

Abstract

The application provides a perovskite tandem solar cell and a preparation method and application thereof, a surface of the wide-bandgap perovskite layer is subjected to passivation treatment, the defect density of the wide-bandgap perovskite layer is reduced, non-radiative recombination is reduced, a two-dimensional perovskite phase is formed, the hydrophobicity of the device is improved, the stability of the device to water is greatly reduced, the loss of an open voltage is reduced, and the open voltage is improved. The perovskite tandem solar cell prepared based on the method has high photoelectric conversion efficiency and good device stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of optoelectronic materials and devices, and relates to a full-perovskite tandem solar cell and a preparation method and application thereof. BACKGROUND

[0002] The large-scale exploitation and utilization of fossil energy is intensifying global climate change, and developing clean energy has become the consensus of the whole society. In recent years, major economies have formulated strategies to vigorously develop solar, wind, water and tidal energy and other new types of renewable energy sources, and the total proportion of clean energy is continuously increasing. Solar energy is a clean energy with huge reserves, with about 800,000 kilowatts of solar energy reaching the earth every second, and the solar energy reaching the earth in a year is equivalent to the energy released by burning 13 trillion tons of standard coal. If 0.013% of the solar energy can be completely converted and utilized, it can meet the needs of the current production and life of mankind. The existing crystalline silicon solar cells have achieved large-scale application, but their photoelectric conversion efficiency is approaching the limit of industrialization. Therefore, developing new photovoltaic technologies with higher efficiency, breaking through the limit of traditional crystalline silicon cells, and further reducing the cost of photovoltaic power generation and land occupation have become the key to solar cell research. Building a tandem solar cell is an effective way to greatly improve the efficiency of solar cells. The theoretical efficiency of a double-junction tandem cell can be more than 42%, much higher than the S-Q limit of 33% for a single-junction cell. Although traditional III-V semiconductor tandem cells have achieved high efficiency, the preparation process is complex and the cost is high, which cannot achieve low-cost power generation. Perovskite solar cells are attracting attention and developing rapidly due to their low cost, easy preparation, and excellent optoelectronic performance. The cell conversion efficiency has increased from 3.8% in 2009 to 25.7% in 2022, and is considered to be the next generation of low-cost high-efficiency photovoltaic technology with the most application prospects. The perovskite / perovskite (or "full perovskite") tandem solar cell constructed by interconnecting wide and narrow bandgap perovskite subcells has the outstanding advantages of high efficiency and low cost, and is the next generation of high-efficiency, low-cost photovoltaic technology.

[0003] Tandem perovskite-based cells are usually composed of a wide bandgap (WBG ~ 1.7-1.8 eV) perovskite and a low bandgap (NBG). The bottom cell collects low-energy photons, such as c-Si, copper indium gallium diselenide (CIGS), and hybrid tin (Sn) lead (Pb) perovskite, which has attracted considerable interest. So far, certified PCEs of 29.8%, 24.2%, and 26.4% have been achieved for perovskite / Si, perovskite / CIGS, and perovskite / perovskite TSCs, respectively, providing great prospects. However, the PCEs of perovskite-based TSCs are still far below their theoretical efficiency limits, mainly due to the presence of defects in the bulk and surface of Br-rich perovskite absorbers, resulting in poor performance of WBG PSCs, generating a large open-circuit voltage (Voc) loss.OC )loss (defined as E g / q-V OC , where q is the elementary charge). In addition, light-induced (I)-(Br) phase separation also impairs the stability of WBG perovskites, resulting in an undesirable stability of the tandem perovskite solar cells.

[0004] WBGPSC still suffers from severe open-circuit voltage loss and instability. The high open voltage loss is attributed to high defect density and light-induced phase separation. The polycrystalline perovskite films prepared by the solution method have many defects at the grain boundaries, surfaces and perovskite bodies, which will cause strong non-radiative recombination. Non-radiative recombination reduces the steady-state charge density, reduces the splitting of the quasi-Fermi level, and ultimately leads to relatively large open voltage loss. In addition, surface defects at the grain boundaries provide channels for water intrusion and ion migration, resulting in adverse stability. In view of the above problems, researchers improve the quality of WBG perovskite films, passivate surface defects, optimize the energy level arrangement, greatly reduce VOC loss and WBG performance through composition engineering, additive engineering and interface engineering and other methods. Based on this, the team carried out a series of researches, aiming to find a more effective method to solve these problems. SUMMARY

[0005] The technical problem solved by the present application is that the wide band gap perovskite solar cell has a serious open voltage loss, thereby limiting the improvement of photovoltaic performance. The present application provides a full perovskite tandem solar cell and a preparation method and application thereof, and the performance of the full perovskite tandem solar cell is excellent by adjusting the concentration of the electron transport layer PCBM of the wide band gap perovskite.

[0006] The technical scheme is specifically as follows:

[0007] A method for preparing a full perovskite tandem solar cell based on ion liquid wide band gap crystallization regulation engineering, comprising:

[0008] Step 1: prepare Cs x MA 1-x PbI 2.4 Br 0.6 Wide band gap perovskite precursor solution and narrow band gap perovskite precursor solution, wherein X=0.3, 0.5, 0.6, 0.7; step 2: forming a first hole transport layer on ITO conductive glass; step 3: hot spin coating the Cs x MA 1- x PbI 2.4 Br 0.6A wide band gap perovskite precursor solution is prepared, and a wide band gap perovskite layer is obtained after annealing treatment; step 4: the surface of the wide band gap perovskite layer is passivated; step 5: a first electron transport layer is formed on the side of the wide band gap perovskite layer away from the first hole transport layer; step 6: a tin oxide interconnection layer is formed on the side of the first electron transport layer away from the wide band gap perovskite layer; step 7: a composite layer is formed on the side of the tin oxide interconnection layer away from the electron transport layer; step 8: a second hole transport layer is formed on the side of the composite layer away from the tin oxide interconnection layer; step 9: the narrow band gap perovskite precursor solution prepared in step 1 is spin-coated on the side of the second hole transport layer away from the composite layer, and a narrow band gap perovskite layer is obtained after annealing treatment; and step 10: a second electron transport layer, a hole blocking layer and a metal electrode are sequentially prepared on the narrow band gap perovskite layer.

[0009] A further technical solution of the present application is:

[0010] The Cs x MA 1-x PbI 2.4 Br 0.6 The wide band gap perovskite precursor solution is Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 The wide band gap perovskite precursor solution.

[0011] A further technical solution of the present application is:

[0012] The Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 The preparation process of the wide band gap perovskite precursor solution includes the following steps: dissolving cesium iodide, cesium bromide, lead iodide and methylamine bromide in MAAc ionic liquid, heating and stirring to dissolve, to obtain the Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 The wide band gap perovskite precursor solution.

[0013] A further technical solution of the present application is:

[0014] The Cs 0.6 MA 0.4 PbI 2.4 Br 0.6The preparation process of the wide band gap perovskite precursor solution comprises the following steps: dissolving 47.8 mg of cesium iodide, 19.6 mg of cesium bromide, 212 mg of lead iodide and 20.6 mg of methylamine bromide in MAAc ionic liquid, and stirring and dissolving at a temperature of 120 DEG C for 1-4 hours to obtain the Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 The wide band gap perovskite precursor solution.

[0015] The further technical scheme of the present application is:

[0016] The narrow band gap perovskite precursor solution is FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The narrow band gap perovskite precursor solution.

[0017] The further technical scheme of the present application is:

[0018] The FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The preparation of the FA

[0019] Step (1): adding FAI, MAI, PbI2 and SnI2 into SnF2, adding a mixed solution of DMF:DMSO with a volume ratio of 2:1, and stirring and dissolving, wherein the molar ratio of FAI:MAI:PbI2:SnI2 is 0.7:0.3:0.5:0.5, and the molar ratio of SnF2:SnI2 is 0.1:1;

[0020] Step (2): adding tin powder and formamidine sulfurous acid into the mixed solution obtained in step (1) and stirring and dissolving, wherein the addition amount of the tin powder is 4-6 mg / mL, and the addition amount of the formamidine sulfurous acid is 0.2-0.5 mol%;

[0021] Step (3): adding an additive into the mixed solution obtained in step (2) and stirring and dissolving, wherein the additive is at least one of PEACl, PACl or CF3-PACl, and the concentration of the introduced additive with respect to the metal cation in the b site is less than 0.4 mol%;

[0022] Step (4): filtering the mixed solution obtained in step (3) through a polytetrafluoroethylene membrane to obtain the FA 0.7 MA 0.3 Pb 0.5 Sn 0.5I3 narrow bandgap perovskite precursor solution.

[0023] The further technical solution of the present application is:

[0024] The thermal spin coating in step 3 comprises the following steps: heating the ITO conductive glass with the first hole transport layer to 90-100 DEG C, and spin coating the wide bandgap perovskite precursor solution prepared in step 1 on the side of the first hole transport layer away from the ITO conductive glass at a rotation speed of 2500 rpm for 15-25 seconds.

[0025] The further technical solution of the present application is:

[0026] The annealing temperature in step 3 is 100-120 DEG C, and the processing time is 5-10 minutes.

[0027] The further technical solution of the present application is:

[0028] The first hole transport layer is P3CT.

[0029] The further technical solution of the present application is:

[0030] The passivation treatment in step 4 comprises the following steps: dropping 4-fluorophenethyl iodide amine solution dissolved in IPA on the surface of the wide bandgap perovskite layer, staying for 10-20 seconds, and then spin coating at a rotation speed of 2200-5000 rpm for 40-60 seconds.

[0031] The further technical solution of the present application is:

[0032] The first electron transport layer in step 5 is formed by spin coating and vacuum evaporation.

[0033] The further technical solution of the present application is:

[0034] The first electron transport layer in step 5 is formed by spin coating 5-15 mg / mL PCBM on the side of the passivated wide bandgap perovskite layer away from the first hole transport layer, and vacuum evaporation on the side of the passivated wide bandgap perovskite layer away from the first hole transport layer to form a first electron transport layer with a thickness of 10-30 nm and a raw material of fullerene C 60 .

[0035] The further technical solution of the present application is:

[0036] The tin oxide interconnection layer in step 6 is formed by atomic layer deposition; preferably, the thickness of the tin oxide interconnection layer is 30 nm.

[0037] A further technical solution of the present application is:

[0038] The composite layer in step 7 is formed by evaporation, preferably, the raw material of the composite layer is gold, more preferably, the thickness of the composite layer is 1 nm.

[0039] A further technical solution of the present application is:

[0040] The second electron transport layer in step 10 is formed by thermal evaporation, and the hole blocking layer is formed by evaporation.

[0041] A further technical solution of the present application is:

[0042] The raw material of the second electron transport layer in step 10 is fullerene C 60 , the raw material of the hole blocking layer is BCP, and the raw material of the metal electrode is copper.

[0043] A further technical solution of the present application is:

[0044] The thickness of the second electron transport layer in step 10 is 20 nm, the thickness of the hole blocking layer is 7 nm, and the thickness of the metal electrode is 150 nm.

[0045] A further technical solution of the present application is:

[0046] The second hole transport layer in step 8 is formed by spin coating.

[0047] A further technical solution of the present application is:

[0048] The raw material of the second hole transport layer is PEDOT:PSS.

[0049] A further technical solution of the present application is:

[0050] In step 8, the second hole transport layer is formed by spin coating PEDOT:PSS on the composite layer at a speed of 2200-4000 rpm in air, the spin coating time is 25-35 seconds, and then the sample is immediately transferred to a hot table for annealing at 140-160℃ for 8-15 minutes, and then cooled to room temperature and transferred into a glove box for standby.

[0051] A further technical solution of the present application is:

[0052] The spin coating process in step 9 comprises: taking the narrow-bandgap perovskite precursor and dropping it on the side of the second hole transport layer away from the tin oxide interconnection layer, performing the first step of spin coating, and then performing the second step of spin coating; 15-25 seconds before the end of the second step of spin coating, taking 300 muL of EA as an anti-solvent and dropping it on the side of the second hole transport layer away from the tin oxide interconnection layer to make the narrow-bandgap perovskite into an intermediate phase.

[0053] A further technical solution of the present application is:

[0054] The rotation speed of the first step of spin coating is 1000 revolutions / minute, the acceleration is 200 revolutions / second, and the spin coating time is 8-15 seconds.

[0055] A further technical solution of the present application is:

[0056] The rotation speed of the second step of spin coating is 4000 revolutions / minute, the acceleration is 1000 revolutions / second, and the spin coating time is 35-45 seconds.

[0057] A further technical solution of the present application is:

[0058] The annealing temperature in step 9 is 100-120 DEG C, and the processing time is 5-10 minutes.

[0059] The technical solutions are specifically as follows:

[0060] A full perovskite tandem solar cell prepared based on ion liquid wide-bandgap crystallization regulation engineering comprises: ITO conductive glass; a first hole transport layer formed on the ITO conductive glass; a wide-bandgap perovskite layer subjected to passivation treatment and formed on the side of the first hole transport layer away from the ITO conductive glass; a first electron transport layer formed on the side of the wide-bandgap perovskite layer subjected to passivation treatment away from the first hole transport layer; a tin oxide interconnection layer formed on the side of the first electron transport layer away from the wide-bandgap perovskite layer subjected to passivation treatment; a composite layer formed on the side of the composite layer away from the tin oxide interconnection layer; a second hole transport layer formed on the side of the second hole transport layer away from the composite layer; a narrow-bandgap perovskite layer formed on the side of the narrow-bandgap perovskite layer away from the second hole transport layer; a second electron transport layer formed on the side of the second electron transport layer away from the narrow-bandgap perovskite layer; a hole blocking layer formed on the side of the hole blocking layer away from the second electron transport layer; and a metal electrode formed on the side of the hole blocking layer away from the second electron transport layer.

[0061] The technical solutions are specifically as follows:

[0062] The application of a full perovskite tandem solar cell as described above or a full perovskite tandem solar cell prepared by the method as described above in the field of optoelectronics.

[0063] Advantages

[0064] The present application provides a method for preparing a full perovskite tandem solar cell based on ion liquid crystallization regulation engineering, which addresses the technical problem of serious open-circuit voltage loss of wide-bandgap perovskite solar cells, thereby limiting the improvement of photovoltaic performance. The surface of the wide-bandgap perovskite layer is passivated to reduce the defect density of the wide-bandgap perovskite layer, reduce non-radiative recombination, form a two-dimensional perovskite phase, improve the hydrophobicity of the device, and greatly reduce the loss of open-circuit voltage, thereby improving the open-circuit voltage. The full perovskite tandem solar cell prepared by the method has high photoelectric conversion efficiency and good device stability.

[0065] The present application has the following advantages:

[0066] (1) The present application provides a Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution, by regulating the composition of A site and adding Cs component, by regulating the ratio of Cs and MA in the wide-bandgap perovskite precursor solution, a Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution, which meets the optimal bandgap range of the wide-bandgap perovskite layer in the full perovskite tandem solar cell.

[0067] (2) The use of aprotic ionic liquid as the solvent for perovskite components in the wide-bandgap perovskite precursor solution can achieve the purpose of preparing a wide-bandgap perovskite layer in air, greatly improve the repeatability of the wide-bandgap perovskite layer preparation, and improve the quality of the wide-bandgap perovskite layer.

[0068] (3) The present application uses 4-fluorophenethyl iodide to passivate the surface of the wide-bandgap perovskite layer. This interface modification method reduces the defect density, reduces non-radiative recombination, forms a two-dimensional perovskite phase, improves the hydrophobicity of the device, and greatly reduces the loss of open-circuit voltage, thereby improving the open-circuit voltage.

[0069] (4) The present application spins 5-15 mg / mL PCBM on the side of the passivated wide-bandgap perovskite layer away from the first hole transport layer to form a first electron transport layer. By regulating the concentration of the first electron transport layer PCBM on the wide-bandgap perovskite layer, a full perovskite tandem solar cell with excellent performance is prepared.

[0070] (5) The preparation method in the application has good repeatability, safety and environmental protection, and promotes the development of the photovoltaic industry to a certain extent.

[0071] (6) The electron transport layer of the wide-bandgap perovskite layer in the application is a PCBM / fullerene C60 double electron transport layer, which can passivate the defects on the surface of the wide-bandgap perovskite layer, effectively reduce the non-radiative recombination between interfaces, and significantly improve the photoelectric conversion efficiency of the device.

[0072] (7) The application in the FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 In the preparation of the I3 narrow-bandgap perovskite precursor solution, tin powder and formamidinium sulfite are added to reduce the Sn 4+ content in the narrow-bandgap perovskite precursor solution and improve the uniformity of the film. For the passivation agent solution, PEACl, PACl or CF3-PACl is added in the narrow-bandgap perovskite precursor solution at an optimal concentration. The concentration of the introduced additive relative to the b-site metal cation is less than 0.4 mol%, which is lower than the concentration of the large a-site cation required to form a 2D / 3D heterostructure. BRIEF DESCRIPTION OF DRAWINGS

[0073] Figure 1 The Cs x MA 1-x PbI 2.4 Br 0.6 perovskite layer, and the characterization of the ultraviolet-visible absorption spectrum (UV-vis);

[0074] Figure 2 The structure of the wide-bandgap perovskite solar cell in Example 3 of the application is shown in the figure;

[0075] Figure 3 The current-voltage curve of the standard part of the wide-bandgap perovskite solar cell in Examples 2 and 3 of the application and the device after the upper interface is passivated by 4-fluorophenethyl iodide is shown in the figure;

[0076] Figure 4 The X-ray diffraction pattern of the wide-bandgap perovskite layer in the wide-bandgap perovskite solar cell in Example 2 of the application is shown in the figure;

[0077] Figure 5a The contact angle test figures of the standard part without passivation treatment and the device after the upper interface is passivated by 4-fluorophenethyl iodide are shown in the figure;

[0078] Figure 6a, b is the current-voltage curve and EQE diagram of the all-perovskite tandem solar cell prepared by the method in Example 4 of the application;

[0079] Figure 7 is a structural schematic diagram of the all-perovskite tandem solar cell of the application;

[0080] Figure 8 is the current-voltage curve of the best all-perovskite tandem solar cell prepared by the application. DETAILED DESCRIPTION

[0081] The application will be further described in combination with examples and drawings:

[0082] Example 1

[0083] The purpose of this example is to verify the composition of the wide-bandgap perovskite precursor solution, the laboratory humidity condition of this example is about 30%, and the temperature is 20℃, mainly including the following steps:

[0084] Step 1: The etched quartz wafer is sequentially ultrasonically cleaned in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After nitrogen blowing, the clean quartz wafer is stored in an electronic drying cabinet.

[0085] Step 2: Adjust the Cs x MA 1-x PbI 2.4 Br 0.6 The composition of the wide-bandgap perovskite precursor solution, wherein X = 0.3, 0.5, 0.6, 0.7. The corresponding amount of cesium iodide, cesium bromide, lead iodide, and methylamine bromide is dissolved in MAAc ionic liquid, and heated and stirred to dissolve at 120℃ for 1-4 hours;

[0086] Step 3: The clean quartz wafer in step 1 is treated with ultraviolet ozone for 15 minutes;

[0087] Step 4: Take 100 microliters of the wide-bandgap perovskite precursor solution prepared in step 2 and drop it onto the preheated quartz wafer, the preheating temperature of the quartz wafer is 90-100℃, spin-coated into a film (rotation speed is 2500 revolutions / minute, spin-coating time is 20 seconds), then annealed in air at 100℃ for 5 minutes to form a wide-bandgap perovskite layer, and then placed in a nitrogen glove box for standby.

[0088] Step 5: Put the wide-bandgap perovskite layer into a centrifuge tube and test it by ultraviolet-visible absorption spectrum (UV-vis), the experimental results are shown in Figure 1 As can be seen, the composition is Cs 0.6 MA 0.4 PbI 2.4 Br 0.6with a band gap of 1.77 eV, which meets the optimal band gap range of wide band gap in all-perovskite tandem solar cells.

[0089] Example 2

[0090] The present embodiment provides a preparation method of a perovskite solar cell based on an ionic liquid. The humidity in the laboratory is about 30%, and the temperature is 20°C. The preparation method comprises the following steps:

[0091] Step 1: The etched ITO conductive glass is sequentially ultrasonically cleaned in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After nitrogen blowing, clean ITO conductive glass is obtained and stored in a dry cabinet.

[0092] Step 2: Dissolve 47.8 milligrams of cesium iodide, 19.6 milligrams of cesium bromide, 212 milligrams of lead iodide, and 20.6 milligrams of methylamine bromide in MAAc ionic liquid, and heat and stir at 120°C for 1-4 hours to prepare a wide band gap perovskite precursor solution.

[0093] Step 3: Dissolve 15 milligrams of PCBM in 1 milliliter of chlorobenzene solution. After stirring at 400 revolutions per minute for 3 hours at room temperature, the solution is left to stand for more than 4 hours.

[0094] Step 4: The clean ITO conductive glass in step 1 is treated in an ultraviolet ozone environment for 15 minutes.

[0095] Step 5: Take 20 microliters of hole transport layer precursor solution (P3CT solution) and drop it onto the ITO conductive glass treated in step 4. Use a spin coater to spin coat a film at a speed of 4000 revolutions per minute for 30 seconds. Then, place the P3CT-coated substrate on a hot stage at 100°C for 10 minutes of annealing treatment to form a first hole transport layer.

[0096] Step 6: Take 100 microliters of the wide band gap perovskite precursor solution prepared in step 2 and drop it onto the preheated first hole transport layer away from the ITO conductive glass. The preheating temperature is 50-100°C. Spin coat a film at a speed of 2500 revolutions per minute for 30 seconds. After annealing at 100°C for 5 minutes in air, a wide band gap perovskite layer is formed. The obtained wide band gap perovskite layer is placed in a nitrogen glove box for standby. The X-ray diffraction test of the wide band gap perovskite layer is shown in Figure 4

[0097] Step 7: Take 25 microliters of the supernatant of the PCBM solution prepared in step 3 and drop it onto the surface of the wide band gap perovskite layer in step 6. Spin coat a film at a speed of 1000 revolutions per minute for 60 seconds without annealing.

[0098] ​Step 8: After the first electron transport layer of PCBM is spin-coated, the BCP material is evaporated using a crucible, the evaporation temperature is 100°C, the shutter is opened after the rate is stable, and the BCP hole blocking layer with a thickness of 7 nanometers is evaporated at a rate of 0.1 angstrom / second. Subsequently, the vacuum evaporation method is continued, and silver (80 nanometers) is evaporated on the above sample at a rate of 1 angstrom / second, completing the preparation of the perovskite solar cell.

[0099] Step 9: Under standard test conditions (AM1.5G light), the optimal battery device prepared in this embodiment has an energy conversion efficiency of 13.9%, an open circuit voltage of 1.11V, a short circuit current of 15.6mA / cm 2 , and a fill factor of 80.2%.

[0100] Example 3

[0101] This embodiment provides a preparation method of a wide-bandgap perovskite solar cell based on an ionic liquid using 4-fluorophenethyl iodide amine for interface passivation, the laboratory humidity condition is about 30%, and the temperature is 20°C, including the following steps:

[0102] Step 1: The etched ITO conductive glass is sequentially ultrasonically cleaned in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After nitrogen blowing, clean ITO conductive glass is obtained and stored in a dry cabinet.

[0103] Step 2: Dissolve 47.8 milligrams of cesium iodide, 19.6 milligrams of cesium bromide, 212 milligrams of lead iodide, and 20.6 milligrams of methylamine bromide in MAAc ionic liquid, heat and stir at 120°C for 1-4 hours to prepare a wide-bandgap perovskite precursor solution.

[0104] Step 3: Dissolve 15 milligrams of PCBM in 1 milliliter of chlorobenzene solution. After stirring at 400 revolutions per minute for 3 hours, the solution is left to stand for more than 4 hours.

[0105] Step 4: The clean ITO conductive glass in step 1 is treated in an ultraviolet ozone environment for 15 minutes.

[0106] Step 5: Take 20 microliters of hole transport layer precursor solution (P3CT solution) and drop it onto the ITO conductive glass treated in step 4. Use a spin coater to spin coat a film at a speed of 4000 revolutions per minute for 30 seconds. Then place the P3CT-coated sample on a hot stage at 100°C for 10 minutes of annealing treatment to form the first hole transport layer.

[0107] Step 6: 100 microliters of the prepared wide bandgap perovskite precursor solution in step 2 was dropped on the first hole transport layer of the preheated ITO conductive glass, the preheating temperature was 50-100℃, and the film was formed by spin coating at 2500 rpm for 30 seconds. After annealing at 100℃ for 5 minutes in air, a wide bandgap perovskite layer was formed and stored in a nitrogen glove box for later use. 90 microliters of 4-fluorophenethyl iodide amine solution dissolved in IPA was added to the surface of the wide bandgap perovskite layer, and spin coating was performed after 10 seconds, with a rotation speed of 5000 rpm for 50 seconds.

[0108] Step 7: 25 microliters of the supernatant of the PCBM solution prepared in step 3 was dropped onto the surface of the wide bandgap perovskite layer in step 6, and the film was formed by spin coating at 1000 rpm for 60 seconds without annealing.

[0109] Step 8: After spin coating the first electron transport layer of PCBM, BCP material was evaporated using a crucible, the evaporation temperature was 100℃, and after the rate was stable, the shutter was opened, and a 7 nanometer thick BCP hole blocking layer was evaporated at a rate of 0.1 angstrom / second. Subsequently, vacuum evaporation was continued, and silver (80 nanometers) was evaporated on the above sample at a rate of 1 angstrom / second, completing the preparation of the perovskite solar cell.

[0110] Step 9: Under standard test conditions (AM1.5G light), the optimal battery device prepared in this example had an energy conversion efficiency of 18.5%, an open circuit voltage of 1.21V, a short circuit current of 18.9mA / cm 2 , and a fill factor of 80.6%.

[0111] Example 4

[0112] This example provides a method for preparing a full perovskite tandem solar cell based on ion liquid wide bandgap crystal regulation engineering, the laboratory humidity conditions are about 30%, and the temperature is 20℃, which includes the following steps:

[0113] Step 1: The etched ITO conductive glass was sequentially ultrasonically cleaned in ethanol, ultrapure water with cleaning agent, ultrapure water, and ethanol for 15 minutes each. After nitrogen blowing, clean ITO conductive glass was obtained and stored in a dry cabinet.

[0114] Step 2: 39.83 milligrams of cesium iodide, 16.31 milligrams of cesium bromide, 176.69 milligrams of lead iodide, and 17.17 milligrams of methylamine bromide were dissolved in 1 milliliter of methylamine acetate (MAAc) ionic liquid solvent, and heated and stirred at 120℃ for 1-4 hours to prepare a wide bandgap perovskite precursor solution.

[0115] Step 3: FA 0.7 MA 0.3 Pb0.5 Sn 0.5 Preparation of I3 narrow-bandgap perovskite precursor solution: FAI, MAI, PbI2, SnI2 were added into SnF2, and a mixed solution of DMF:DMSO with a volume ratio of 2:1 was added, and the solution was stirred and dissolved, wherein the molar ratio of FAI:MAI:PbI2:SnI2 was 0.7:0.3:0.5:0.5, and the molar ratio of SnF2:SnI2 was 0.1:1. The precursor solution was stirred at room temperature for 2 hours. Tin powder and formamidinium sulfite were added to the narrow-bandgap perovskite precursor solution, and the solution was stirred and dissolved, wherein the addition amount of tin powder was 5 mg / mL, and the addition amount of formamidinium sulfite was 0.3 mol%. A passivation agent solution was added, and PEACl, PACl or CF3-PACl was added to the precursor solution at an optimal concentration, wherein the concentration of the introduced additive with respect to the b-site metal cation was less than 0.4 mol%, which was lower than the concentration of the large a-site cation required to form a 2D / 3D heterostructure. The precursor solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane to prepare a perovskite thin film. The weighing, stirring and storage processes were all carried out in a glove box.

[0116] Step 4: 10 mg of PCBM was dissolved in 1 mL of chlorobenzene solution, and the solution was stirred at room temperature at 400 rpm for 3 hours, and then stood for more than 4 hours.

[0117] Step 5: The ITO conductive glass cleaned in step 1 was treated in an ultraviolet ozone environment for 15 minutes.

[0118] Step 6: 20 μL of hole transport layer precursor solution (P3CT solution) was dropped onto the ITO conductive glass treated in step 4, and a spin coater was used to spin-coat a film at a speed of 4000 rpm for 30 seconds. The P3CT-coated substrate was then placed on a hot stage at 100°C for 10 minutes of annealing treatment to form a first hole transport layer.

[0119] Step 7: 100 μL of the wide-bandgap perovskite precursor solution prepared in step 2 was dropped onto the first hole transport layer away from the ITO conductive glass after preheating, the preheating temperature was 50-100°C, and the film was spin-coated at a speed of 2500 rpm for 30 seconds. After annealing at 100°C in air for 5 minutes, a wide-bandgap perovskite layer was formed, which was placed in a nitrogen glove box for standby. 90 μL of 4-fluorophenethyl iodide amine solution dissolved in IPA was dropped onto the surface of the wide-bandgap perovskite layer, and spin-coating was performed after standing for 10 seconds, with a speed setting of 5000 rpm for 50 seconds.

[0120] Step 8: Take 25 μL of the supernatant from the PCBM solution after settling in Step 4 and drop it onto the surface of the wide-bandgap perovskite layer from Step 7. Spin-coat the layer at 1000 rpm for 60 seconds, without annealing. Electron transport layer material C is deposited using vacuum evaporation. 60 First, a 1-nanometer thick C layer is deposited at a rate of 0.1 Å / s. 60 Then, a 19-nanometer-thick C layer was deposited at a rate of 0.5 Å / s. 60 With a total thickness of 20 nanometers, C 60 As a charge transport layer;

[0121] Step 9: Deposit tin oxide as an interconnect layer using atomic layer deposition (ALD). First, transfer the sample to the equipment, set the tin source to 55°C, and after the pressure stabilizes, set the deposition cycle to 300, corresponding to a thickness of 30 nanometers. After deposition is complete, turn off the tin source and remove the sample when the pressure is atmospheric pressure. Then, deposit a 1-nanometer-thick layer of metallic gold on the tin oxide as a composite layer for later use.

[0122] Step 10: In an air environment, spin coat PEDOT:PSS onto the composite layer at a speed of 4000 rpm for 30 seconds. After spin coating, immediately transfer to a hot plate and anneal at 150°C for 10 minutes. After annealing, cool to room temperature and transfer to a glove box for later use.

[0123] Step 11: Place the substrate with the PEDOT:PSS second hole transport layer deposited in Step 10 onto a spin coater. Add 200 μL of narrow bandgap perovskite precursor to the side of the PEDOT:PSS second hole transport layer opposite to the tin oxide interconnect layer, performing the first spin coat. Then perform the second spin coat. 20 seconds before the end of the second spin coat, add 300 μL of EA as an antisolvent to the side of the PEDOT:PSS second hole transport layer opposite to the tin oxide interconnect layer, transforming the narrow bandgap perovskite into an intermediate phase. The spin coat speed in the first step is 1000 rpm, the acceleration is 200 rpm, and the spin coat time is 10 seconds. The spin coat speed in the second step is 4000 rpm, the acceleration is 1000 rpm, and the spin coat time is 10 seconds. Anneal on a hot plate at 100°C for 10 minutes, cool to room temperature, and proceed to the next experiment.

[0124] Step 12: Deposit the second electron transport layer C using vacuum evaporation. 60 First, a 1-nanometer thick C layer is deposited at a rate of 0.1 Å / s. 60 Then, a 19 nm thick C60 layer was deposited at a rate of 0.5 Å / s, followed by a C layer with a total thickness of 20 nm. 60 As a charge transport layer;

[0125] Step 13: Vacuum evaporation of C60 Afterwards, the BCP material was evaporated using a crucible, the evaporation temperature was 100℃, the shutter was opened after the rate was stable, the BCP was evaporated to a thickness of 5nm at a rate of 0.1 angstrom / s, then vacuum evaporation was continued, copper (150nm) was evaporated on the sample at a rate of 1 angstrom / s, and the device preparation was completed;

[0126] Step 14: The optimal battery device prepared in this embodiment has an energy conversion efficiency of 22.4% under standard test conditions (AM1.5G illumination), an open circuit voltage of 1.93V, a short circuit current of 14.8mA / cm 2 , and a fill factor of 78.4%.

[0127] Summary: Through the above examples, the 4-fluorophenethyl amine iodide is used to modify the upper interface of the wide-bandgap perovskite and regulate the concentration of the electron transport layer PCBM of the wide-bandgap perovskite to prepare a full perovskite tandem solar cell with excellent performance. Figure 1 It can be seen that by adjusting the wide-bandgap perovskite Cs x MA 1-x PbI 2.4 Br 0.6 The ultraviolet-visible absorption spectrum (UV-vis) of the component X=0.3, 0.5, 0.6, 0.7, the band gap is about 1.77eV when X is 0.6, which is suitable for the bottom wide-bandgap perovskite of the full perovskite tandem solar cell. This can be confirmed in Example 1. Through Figure 3 It can be seen that the device performance after the wide-bandgap perovskite is passivated by 4-fluorophenethyl amine iodide is much higher than that of the standard piece without passivation, especially the open voltage is significantly improved. In addition, through Figure 5a , b also confirms that the contact angle after interface passivation is larger, and the increased contact angle indicates that this interface passivation can effectively improve the film stability and prevent water and oxygen corrosion. Example 5 is the best example, that is, when the 4-fluorophenethyl amine iodide is used to modify the upper interface of the wide-bandgap perovskite and 10mg / mL PCBM is used as the electron transport layer of the bottom cell, the performance of the device prepared is the best.

[0128] The method for preparing a full perovskite tandem solar cell based on ion liquid wide-bandgap crystallization regulation engineering of the application has the following beneficial effects:

[0129] 1. The method for modifying the upper interface of the wide-bandgap perovskite using 4-fluorophenethyl amine iodide reduces the defect density, reduces non-radiative recombination, forms a two-dimensional perovskite phase, the contact angle is significantly increased, the hydrophobicity and water stability of the device are improved, the loss of open voltage is greatly reduced, and the performance of the device is improved.

[0130] 2. There are some Pb-I anti-site deep level defects in the grain boundary of perovskite. The introduction of PCBM in the wide band gap perovskite solar cell can enhance the charge transport before Pb-I, so as to change the energy band structure and improve the transport of carriers. In addition, the roughness of the surface of the ionic liquid perovskite is large, which is not conducive to the interface contact. The solvent chlorobenzene of PCBM can flush the surface of the film to reduce the roughness, and PCBM acts as a supplement to improve the interface contact.

[0131] 3. A dense SnO2 layer is prepared by atomic layer deposition to replace ITO. The dense SnO2 well blocks the damage of the solvent to the wide band gap top cell (narrow band gap sub-cell preparation process); then, the construction of a high-efficiency composite layer is realized by introducing Au nanoclusters.

[0132] 4. The preparation of two sub-cell perovskites is suitable for large-area preparation and is conducive to the commercialization process.

[0133] Comparative Example 1

[0134] The preparation method of the ionic liquid-based wide band gap perovskite solar cell of the present example is basically the same as that of Example 3, and the difference from Example 3 is that the concentration of 4-fluorophenethyl amine iodide is different. The specific performance parameters are shown in Table 1. The thickness corresponding to the different interface passivation concentrations will also be different. The passivation layer should be thin enough to allow the charge to pass through, increase the number of carriers, and improve the performance. According to Table 1, it can be seen that the optimal concentration of 4-fluorophenethyl amine iodide is 2 mg / mL, and the device performance reaches the best.

[0135] Table 1

[0136]

[0137] Comparative Example 2

[0138] The preparation method of the all-perovskite stacked perovskite solar cell of the present example is basically the same as that of Example 4, and the difference is that the component amount of the wide band gap perovskite precursor is 47.8 milligrams of cesium iodide, 19.6 milligrams of cesium bromide, 212 milligrams of lead iodide, and 20.6 milligrams of methylamine bromide. And adjust the concentration of PCBM in the wide band gap perovskite solar cell. The specific performance parameters are shown in Table 2. According to Table 2, it can be seen that when the PCBM concentration is 10 mg / mL, the device performance reaches the best, and the highest efficiency can reach 24.2%.

[0139] Table 2

[0140]

[0141]

[0142] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fabricating all-perovskite tandem solar cells based on wide-bandgap crystallization control engineering using ionic liquids, characterized in that, include: Step 1: Prepare Cs x MA 1-x PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution and narrow-bandgap perovskite precursor solution; Step 2: Form the first hole transport layer on the ITO conductive glass; Step 3: Spin-coat the Cs prepared in step 1 onto the side of the first hole transport layer opposite to the ITO conductive glass using a thermal coating. x MA 1-x PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution, after annealing, yields wide-bandgap perovskite layer. Step 4: Take 4-fluorophenylethylamine iodide solution and drop it onto the surface of the wide-bandgap perovskite layer to passivate it and form a passivation layer; Step 5: Form a first electron transport layer on the side of the passivated wide-bandgap perovskite layer opposite to the first hole transport layer; Step 6: Form a tin oxide interconnect layer on the side of the first electron transport layer opposite to the wide-bandgap perovskite layer; Step 7: Form a composite layer on the side of the tin oxide interconnect layer opposite to the electron transport layer; Step 8: Form a second hole transport layer on the side of the composite layer opposite to the tin oxide interconnect layer; Step 9: Spin-coat the narrow bandgap perovskite precursor solution prepared in step 1 on the side of the second hole transport layer away from the composite layer, and then anneal it to obtain a narrow bandgap perovskite layer. Step 10: Sequentially fabricate a second electron transport layer, a hole blocking layer, and a metal electrode on the narrow bandgap perovskite layer.

2. The method according to claim 1, characterized in that, The Cs x MA 1-x PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution is Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution; The narrow-bandgap perovskite precursor solution is FA. 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3 narrow bandgap perovskite precursor solution.

3. The method according to claim 2, characterized in that, The Cs 0.6 MA 0.4 PbI 2.4 Br 0.6 The preparation process of the wide-bandgap perovskite precursor solution includes the following steps: dissolving cesium iodide, cesium bromide, lead iodide, and methylamine bromide in MAAc ionic liquid, heating and stirring to dissolve, to obtain the Cs. 0.6 MA 0.4 PbI 2.4 Br 0.6 Wide-bandgap perovskite precursor solution.

4. The method according to claim 2, characterized in that, The FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 The preparation of the I3 narrow bandgap perovskite precursor solution was carried out in a glove box, and the preparation process included the following steps: Step (1): Add FAI, MAI, PbI2, and SnI2 to SnF2, add a DMF:DMSO mixed solution with a volume ratio of 2:1, and stir to dissolve. The molar ratio of FAI:MAI:PbI2:SnI2 is 0.7:0.3:0.5:0.5, and the molar ratio of SnF2:SnI2 is 0.1:

1. Step (2): Add tin powder and formamidine sulfuric acid to the mixed solution obtained in step (1), and stir to dissolve. The amount of tin powder added is 4-6 mg / mL, and the amount of formamidine sulfuric acid added is 0.2-0.5 mol%. Step (3): Add the additive to the mixed solution obtained in step (2) and stir to dissolve. The additive is at least one of PEACl, PACl, or CF3-PACl, and the concentration of the added additive relative to the b-site metal cation is less than 0.4 mol%. Step (4): The mixed solution obtained in step (3) is filtered through a polytetrafluoroethylene membrane to obtain the FA. 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3 narrow bandgap perovskite precursor solution.

5. The method according to claim 1, characterized in that, The spin coating in step 3 includes the following steps: heating the ITO conductive glass on which the first hole transport layer is formed to 90-100°C, and spin coating the wide-bandgap perovskite precursor solution prepared in step 1 onto the side of the first hole transport layer away from the ITO conductive glass at 90-100°C at a rotation speed of 2500 rpm for 15-25 seconds.

6. The method according to claim 5, characterized in that, In step 3, the annealing temperature is 100-120℃ and the treatment time is 5-10 minutes.

7. The method according to claim 5, characterized in that, The first hole transport layer is P3CT.

8. The method according to claim 1, characterized in that, The passivation process described in step 4 includes the following steps: A solution of 4-fluorophenylethylamine iodide dissolved in IPA is dropped onto the surface of the wide-bandgap perovskite layer. After remaining for 10-20 seconds, spin-coating is performed at a speed of 2200-5000 rpm for 40-60 seconds.

9. The method according to claim 1, characterized in that, In step 5, the first electron transport layer is formed by spin coating and vacuum evaporation.

10. The method according to claim 9, characterized in that, In step 5, the first electron transport layer is formed by spin-coating 5-15 mg / mL PCBM onto the side of the passivated wide-bandgap perovskite layer opposite to the first hole transport layer, and then forming a 10-30 nm thick layer of fullerene C on the side of the passivated wide-bandgap perovskite layer opposite to the first hole transport layer by vacuum evaporation. 60 Thus, the first electron transport layer is obtained.

11. The method according to claim 1, characterized in that, The composite layer in step 7 is formed by vapor deposition; the raw material for the composite layer is gold; and the thickness of the composite layer is 1 nm. In step 10, the second electron transport layer is formed by thermal evaporation, and the hole blocking layer is formed by vapor deposition; the raw material for the second electron transport layer is fullerene C. 60 The hole blocking layer is made of BCP, and the metal electrode is made of copper; the thickness of the second electron transport layer is 20 nm, the thickness of the hole blocking layer is 7 nm, and the thickness of the metal electrode is 150 nm.

12. The method according to claim 1, characterized in that, In step 8, the second hole transport layer is formed by spin coating.

13. The method according to claim 12, characterized in that, The material of the second hole transport layer is PEDOT:PSS.

14. The method according to claim 12, characterized in that, In step 8, the second hole transport layer is formed as follows: PEDOT:PSS is spin-coated onto the composite layer in air at a speed of 2200-4000 rpm for 25-35 seconds. After spin-coating, the coating is immediately transferred to a hot plate and annealed at 140-160°C for 8-15 minutes. After annealing, the coating is cooled to room temperature and then transferred to a glove box for later use.

15. The method according to claim 1, characterized in that, Step 9, the spin coating process, includes: The narrow bandgap perovskite precursor is dropped onto the side of the second hole transport layer away from the tin oxide interconnect layer, and a first spin coating is performed. Then a second spin coating is performed. 15-25 seconds before the end of the second spin coating, 300 μL of EA is dropped onto the side of the second hole transport layer away from the tin oxide interconnect layer as an antisolvent, so that the narrow bandgap perovskite becomes the meso phase.

16. The method according to claim 15, characterized in that, The first step of spin coating involves a rotation speed of 1000 rpm, an acceleration of 200 rpm, and a spin coating time of 8-15 seconds.

17. The method according to claim 15, characterized in that, The second step of spin coating involves a spin speed of 4000 rpm, an acceleration of 1000 rpm, and a spin coating time of 35-45 seconds.

18. The method according to claim 15, characterized in that, In step 9, the annealing temperature is 100-120℃ and the treatment time is 5-10 minutes.

19. A fully perovskite tandem solar cell prepared by the method according to any one of claims 1 to 18, characterized in that, include: ITO conductive glass; The first hole transport layer is formed on the ITO conductive glass; A passivated wide-bandgap perovskite layer is formed on the side of the first hole transport layer away from the ITO conductive glass. The first electron transport layer is formed on the side of the passivated wide-bandgap perovskite layer away from the first hole transport layer. A tin oxide interconnect layer is formed on the side of the first electron transport layer away from the passivated wide-bandgap perovskite layer. A composite layer formed on the side of the tin oxide interconnect layer away from the electron transport layer; A second hole transport layer is formed on the side of the composite layer opposite to the tin oxide interconnect layer; A narrow bandgap perovskite layer is formed on the side of the second hole transport layer away from the composite layer; A second electron transport layer is formed on the side of the narrow bandgap perovskite layer away from the second hole transport layer; A hole-blocking layer is formed on the side of the second electron transport layer away from the narrow bandgap perovskite layer. A metal electrode is formed on the side of the hole blocking layer that is away from the second electron transport layer.

20. An application of an all-perovskite tandem solar cell prepared by the method according to any one of claims 1-18 in the field of optoelectronics.

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