Method for preparing alcohol cosolvent carbon-based perovskite solar cell in all-air environment

Abstract

The invention relates to a method for preparing an alcohol cosolvent carbon-based perovskite solar cell in an all-air environment. The solar cell structurally comprises an FTO conductive substrate, an electron transport layer, a perovskite light absorption layer, an inorganic hole transport layer and a carbon electrode, the preparation process of all the functional layers is completely in an air environment condition, the perovskite active layer is prepared by adopting a two-step spin-coating method, and the organic salt in the second step is dissolved by adopting a mixed solvent of isopropanol and methanol. According to the invention, harsh preparation conditions are abandoned, the process is simple, and the purposes of reducing cost and increasing efficiency can be achieved; after the mixed solvent of methanol and isopropanol is introduced, the perovskite active layer has better film forming quality, upper interface defects are passivated, filling factors, short-circuit current density and efficiency are all improved, and the method has better application prospects in the field of manufacturing of single-junction solar cell devices.

Description

Technical Field

[0001] The invention relates to a method for preparing an alcohol co-solvent carbon-based perovskite solar cell in an all-air environment, belonging to the technical field of new energy. Background Art

[0002] In recent years, solar cells have evolved from silicon-based solar cells to perovskite solar cells. Perovskite solar cells have a higher ultimate conversion efficiency (43%) than silicon-based cells, but the problem of device stability has always troubled researchers. Single-junction perovskite cells are simple to prepare and low in cost, but they are made of methylamine ions (MA + ) 、Formamidinium ion (FA + ) and cesium ions (Cs + ) and other components have poor moisture resistance and are difficult to meet actual needs; although the laminated perovskite solar cell has good moisture resistance, its complex structure increases the cost and also increases the difficulty of preparing the battery. The existing methods for preparing perovskite solar cells, such as the perovskite film, hole transport layer and back electrode described in patents CN115954399A, CN115000185A and CN118139493A, are still limited by the troubles of water and oxygen, and need to be carried out under a protective atmosphere such as a glove box, which undoubtedly brings more difficulties to the simplification of the preparation technology and the reduction of costs. Therefore, it is becoming increasingly urgent to develop a technology for preparing single-junction perovskite solar cells in an air environment, which helps to improve the stability of the battery while reducing the cost of the battery and maintaining high-efficiency preparation. At the same time, the organic material spiro-OMeTAD commonly used in the hole transport layer in the current perovskite solar cell structure also limits the stability of the battery and increases the cost of the battery (as described in patent CN118139493A), and finding alternative inorganic materials has also become one of the hot spots in the current perovskite battery research.

[0003] There are many difficulties in preparing perovskite films in an air environment. The one-step method is to dissolve metal halides and organic amine salts in a polar solvent to form a precursor solution, which is then deposited on a substrate to form a film. However, when preparing perovskite films in the one-step method, the use of anti-solvents such as toluene, chlorobenzene (CB), and ethyl acetate (EAC) can improve the crystallinity of the film, but it also brings about the strict control of the dripping window and the trouble of solvent toxicity. Although some researchers use green solvents to replace toxic solvents (as described in patent CN115000185A), the main problems such as the dripping window and operational difficulties cannot be solved. The two-step method is to first prepare a layer of metal halide film, and then react the precursor film with an organic amine salt to prepare a perovskite film. The two-step method can effectively avoid the problems faced by the one-step method, but the crystallinity and film quality are not as good as the one-step method. In the two-step method, there will be many crystal surface defects and water oxygen forming a series of crystal surface pinholes during the perovskite film formation process. These film defects lead to the intensification of ion migration inside the device and the increase of non-radiative recombination losses. In the second step, when the organic solution reacts with precursors such as PbI2 to form ABX3 perovskite film, finding a suitable solvent to effectively reduce grain boundary defects and improve film quality becomes the key. Summary of the invention

[0004] The present invention realizes the preparation of perovskite solar cells directly in an air environment, and has lower costs and simpler preparation conditions compared to other methods that require the preparation of battery devices under the protective atmosphere of a glove box. In addition, by changing the solvent composition in an air environment, the film-forming quality of the two-step perovskite cell is effectively improved, providing a method for preparing alcohol co-solvent carbon-based perovskite solar cells in a full air environment.

[0005] The invention has the advantage that it is prepared in a full air environment, abandoning the harsh conditions of a protective gas atmosphere, and using a mixed solvent of methanol and isopropanol to dissolve organic salts, which is conducive to the rapid nucleation of perovskite films. Methanol has a higher polarity, which drives the nucleation rate to accelerate, thereby improving the film quality of perovskite in an air environment, and improving the carrier mobility between layers. Except for the perovskite active layer, the preparation process of the remaining layers is simple and low-cost, and the prepared carbon-based perovskite solar cell device lays a solid foundation for the large-scale application of single-junction solar cells.

[0006] The technical solution of the present invention for preparing alcohol co-solvent carbon-based perovskite solar cells in an all-air environment is: 1. A method for preparing an alcohol co-solvent carbon-based perovskite solar cell in a full air environment comprises a conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a counter electrode, and the preparation process is completely carried out under air environment conditions.

[0007] 2. The perovskite active layer is prepared by a two-step spin coating method. In the second step, the organic salt is dissolved in a mixed solvent of methanol and isopropanol, wherein the volume ratio of methanol to isopropanol is one or more of 9:1, 8:2, 7:3, 6:4, and 5:5.

[0008] 3. The conductive substrate in the battery structure is one of FTO, ITO, PET / ITO, and PEN / ITO; the electron transport layer is one or more of tin dioxide, titanium dioxide, zinc oxide, aluminum oxide, and magnesium oxide / tin dioxide; the electron transport layer is prepared by chemical bath deposition, spin coating, scraping, inkjet printing, and printing; the perovskite active layer is one or more of MASnX3, CsSnX3, FAPbX3, FASnX3, MAPbX3, CsPbX3, CsFAPbX3, and CsFASnX3; the hole transport layer is spiro-OMeTAD, NiO X , CuSCN, CuI, Cu2O. The counter electrode material is one of carbon paste, gold, silver, and copper; the counter electrode preparation method is one of screen printing, doctor blade method, vacuum sputtering method, and vacuum evaporation method.

[0009] 4. An alcohol co-solvent carbon-based perovskite solar cell prepared in an all-air environment, the preparation of the cell comprising the following steps: S1: The entire preparation process is carried out in a fume hood with ambient air. An electron transport layer is prepared on a conductive substrate. The thickness of the electron transport layer is 10 to 100 nm. After deposition, the electron transport layer is annealed at 150 to 180 degrees for 40 to 60 minutes to complete the preparation of the electron transport layer.

[0010] S2: After the substrate is subjected to wettability treatment, a 0.5-2.0 mg / mL guanidine hydrochloride aqueous solution is spin-coated on the electron transport layer for surface modification, annealed at 120-150 degrees for 20-40 minutes, and then cooled to room temperature for use.

[0011] S3: The perovskite active layer is prepared by a two-step method. The first step is to spin-coat a PbI2 and CsI precursor solution dissolved in DMF and DMSO in a volume ratio of 9:1, and then coat it with an organic salt solution dissolved in methanol and isopropanol in a volume ratio. The thickness of the perovskite active layer is 500-800 nm. After annealing, the preparation of the active layer is completed.

[0012] S4: Cover the surface of the perovskite with a layer of 10-40 mg / mL CuSCN diethyl sulfide solution and let it stand for 20-40 minutes to complete the preparation of the hole layer. The thickness of the hole transport layer is 10-50 nm.

[0013] S5: Finally, a layer of carbon electrode with a thickness of 1 to 50 microns is attached to the above-mentioned hole layer using a scraper method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of alcohol co-solvent carbon-based perovskite solar cells Figure 2 Steady-state fluorescence spectra of alcohol co-solvent carbon-based perovskite films Figure 3 Current density-voltage curves of alcohol co-solvent carbon-based perovskite solar cells DETAILED DESCRIPTION

[0015] The present invention will be described in more detail by the following examples, but the present invention is not limited to these examples. Example

[0016] Preparation method and steps of preparing alcohol co-solvent carbon-based perovskite solar cells in a full air environment: The structure of preparing alcohol co-solvent carbon-based perovskite solar cells in a full air environment is a conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a counter electrode, such as Figure 1 shown.

[0017] 1. Cleaning and treatment of conductive glass substrate FTO. Place a certain number of substrates on a polytetrafluoroethylene cleaning rack, pour 100 mL of detergent, deionized water, isopropanol and anhydrous ethanol into a beaker in turn, and ultrasonicate for 20 minutes respectively. After the last cleaning, put them in a blast drying oven to dry, and then UV ozone for 20 minutes for standby use.

[0018] 2. Prepare the electron transport layer tin dioxide by chemical bath deposition. Dissolve 1.25 g urea, 1.25 mL hydrochloric acid, 25 microliters thioglycolic acid and 275 mg stannous chloride dihydrate in 100 mL deionized water, stir for 1 hour until fully dissolved to complete the preparation of the mother liquor, place the substrate treated in step 1 flat in a container (front side up), place it in a drying oven at 90 ° C for 4 hours, take out the conductive substrate, ultrasonically clean it with deionized water and isopropanol for 5 minutes, and blow dry it with a hair dryer to complete the preparation of the tin dioxide layer.

[0019] 3. Preparation of guanidine hydrochloride buffer layer. Take 4.0 mg of guanidine hydrochloride and dissolve it in 4 mL of deionized water. Stir thoroughly to dissolve. Place the substrate treated in step 2 on a coating machine, set the speed to 5000 rpm, and spin coat the guanidine hydrochloride solution on it for 30 s. Place the substrate on a heating table at 120 °C / 30 min to complete the preparation of the buffer layer. After cooling to room temperature, place it in UV ozone for 20 minutes.

[0020] 4. Prepare the perovskite active layer by two-step method. Take 600.0 mg of PbI2 and 7.0 mg of CsI and dissolve them in 1 mL of DMF and DMSO (volume ratio of 9:1), stir them magnetically for 5 hours to fully dissolve them for use, then take 60.2 mg of FAI, 5.8 mg of MABr and 4.8 mg of MACl and dissolve them in 1 mL of isopropanol and methanol mixed solvent (volume ratio of 8:2), stir them for 1 hour in a dark place to fully dissolve them for use, set the first step of spin coating speed and time to 2500 r / 30 s to complete the preparation of inorganic precursors, anneal at 70°C for 1 min, adjust the speed and time to 2300 r / 30 s in the next step to complete the preparation of organic salt reaction layer, anneal at 150°C for 30 min to complete the preparation of active layer. The use of a mixed solvent of methanol and isopropanol to prepare the perovskite active layer can accelerate the nucleation rate, prevent water and oxygen in the air from corroding the incompletely formed perovskite film, make its surface smoother, i.e. reduce its roughness, improve its hydrophobicity, and at the same time better contact with the hole transport layer. Figure 2 As shown, the intensity of the target group in the PL spectrum becomes lower, indicating that its defects are passivated, thereby improving the carrier transmission rate.

[0021] 5. Preparation of inorganic hole transport layer CuSCN. Take 35 mg of CuSCN powder and dissolve it in 1 mL of diethyl sulfide. Stir it thoroughly for 3 hours until it is completely dissolved. Place the perovskite film substrate prepared in step 4 on a coater, set the speed to 5000 rpm, and spin coat the solution on it for 50 s. Place the substrate in a fume hood and let it stand for 30 minutes to complete the preparation of the hole transport layer.

[0022] 6. Use the doctor blade coating method to complete the preparation of the back electrode. Use a surgical blade to apply the carbon slurry on the sample prepared in the previous step, apply it repeatedly until it is evenly flat, and place it on a heating table at 70°C to dry for 1 hour to complete the preparation of the entire battery device.

[0023] 7. All the above steps are completed in a fume hood with air environment.

[0024] 8. The characterization test of the battery device is as follows: A solar simulator and an electrochemical workstation are used to complete the JV curve test of the battery device and the calculation of its efficiency and fill factor, such as Figure 3 As shown, the efficiency, fill factor, open circuit voltage and short circuit current density of the target group devices shown by the curve in the figure are improved.

Claims

1. A method for preparing alcohol co-solvent carbon-based perovskite solar cells in an all-air environment, characterized in that: The structure of the battery is a conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a counter electrode, and its preparation process is completely carried out under air environment conditions.

2. The perovskite active layer according to claim 1, characterized in that: The method is prepared by a two-step spin coating method, wherein the organic salt is dissolved in a mixed solvent of methanol and isopropanol in the second step, wherein the volume ratio of methanol to isopropanol is one or more of 9:1, 8:2, 7:3, 6:4, and 5:

5.

3. The conductive substrate according to claim 1, wherein: It is one of FTO, ITO, PET / ITO, and PEN / ITO.

4. The electron transport layer according to claim 1, characterized in that: It is one or more of tin dioxide, titanium dioxide, zinc oxide, aluminum oxide, and magnesium oxide / tin dioxide.

5. The perovskite active layer according to claim 2, characterized in that: It is one or more of MASnX3, CsSnX3, FAPbX3, FASnX3, MAPbX3, CsPbX3, CsFAPbX3, and CsFASnX3.

6. The hole transport layer according to claim 1, characterized in that: For spiro-OMeTAD, NiO X , CuSCN, CuI, Cu2O or more.

7. The counter electrode according to claim 1, characterized in that: The material is one of carbon paste, gold, silver, and copper.

8. The method for preparing the electron transport layer as described in claims 4 and 7 is one of chemical bath deposition, spin coating, doctor blade coating, inkjet printing, and printing; the method for preparing the counter electrode is one of screen printing, doctor blade coating, vacuum sputtering, and vacuum evaporation.

9. The thickness of the electron transport layer as claimed in claims 4, 5, 6 and 7 is 10-100 nm, the thickness of the perovskite active layer is 500-800 nm, the thickness of the hole transport layer is 10-50 nm, and the thickness of the carbon electrode is 1-50 μm.

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