Preparation Method of Lead-Free Tin-Based Perovskite Thin Film with Three-Dimensional Structure and Its Solar Cell
By adding formamide iodide salt to the tin-based titaniumite precursor solution, the crystallization process is regulated to form a three-dimensional structure lead-free tin-based perovskite film, which solves the problem of poor film quality and stability, and achieves an efficient and stable photoelectric conversion effect.
Patent Information
- Application Number
- CN202111650270.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-30
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2041-12-30
AI Technical Summary
The existing tin-based perovskite solar cells have problems such as poor film quality, large defect density and poor stability, resulting in low photoelectric conversion efficiency and unstable.
The tin-based perovskite precursor solution is added to the tin-based perovskite precursor solution, and the crystallization process is regulated through its interaction with divalent tin ions to form a three-dimensional structure lead-free tin-based perovskite film to reduce the generation of defects and Sn vacancies.
It significantly improves the quality and stability of the tin-based perovskite film, improves the photoelectric conversion efficiency of solar cells, and maintains efficiency stability for a long time in an oxygen environment.
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Figure CN114583061B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of optoelectronic materials and devices, and relates to a three-dimensional lead-free tin-based perovskite thin film and a preparation method of a solar cell. Background Art
[0002] At present, the shortage problem of traditional fuel energy and the environmental problems caused by its emissions are becoming increasingly prominent. Therefore, the development of renewable clean energy has become one of the important methods to solve the current increasingly serious energy shortage and environmental pollution problems. Among them, solar energy has become the focus of attention due to its unique advantages of rich reserves, green cleanliness, and renewability. Existing crystalline silicon photovoltaic devices have the advantages of high photoelectric conversion efficiency and good stability, but the material cost is high and the process is complex, which hinders their further development. Therefore, the development and search for lower-cost optoelectronic conversion materials have become a hot topic in the photovoltaic field in recent years.
[0003] New organic-inorganic hybrid perovskite materials have great potential in the development and utilization of new solar cells due to their excellent optoelectronic properties such as wide absorption range, low defect density, high absorption coefficient, long carrier diffusion distance, and small exciton binding energy. In just 11 years, the photoelectric conversion efficiency of perovskite solar cells has rapidly increased from 3.8% in 2009 to 25.5% in 2020. This amazing speed is unprecedented. In addition, perovskite photovoltaic devices can be prepared by a simple low-temperature solution method, with a simple preparation process, greatly reducing the production cost, and can be prepared on a large scale, with great industrialization prospects. However, currently, high-efficiency perovskite materials usually contain the heavy metal element lead (Pb), and lead can cause great harm to both the environment and the human body. Therefore, finding an element that can replace lead has become a new research topic.
[0004] In recent years, a large number of studies have been carried out at home and abroad on the development of low-toxic or non-toxic perovskite light-absorbing materials. Among them, tin-based perovskite is considered to be the most likely alternative material. Tin has similar chemical properties to lead, and the band gap of tin-based perovskite is closer to the ideal band gap, with higher energy conversion efficiency. However, due to the fact that divalent tin ions are extremely easy to be oxidized, resulting in problems such as poor film-forming quality, high defect density, and poor stability of the thin film, the prepared solar cell devices have relatively low photoelectric conversion efficiency and poor stability. Summary of the Invention
[0005] Technical Problems to be Solved
[0006] To avoid the deficiencies of the prior art, the present invention proposes a preparation method of a three-dimensional lead-free tin-based perovskite thin film and a solar cell. Specifically, by adding formamidinium iodide salt to the formamidinium tin iodide perovskite precursor solution, the formamidinium iodide salt plays a dual-functional coordination role, which can interact with both the formamidinium group and the divalent tin ion at the same time, connect quasi-perovskite micelles in the precursor solution to increase the micelle size, regulate the crystallization process of the tin-based perovskite thin film, reduce the formation of defects and the generation of Sn vacancies, thereby improving the quality and stability of the tin-based perovskite thin film.
[0007] Technical solution
[0008] A preparation method of a three-dimensional lead-free tin-based perovskite thin film, characterized in that the steps are as follows:
[0009] Step 1: Prepare a precursor solution; dissolve formamidinium iodide, stannous iodide, formamidinium iodide salt in a polar organic solvent, and at the same time add stannous fluoride as an antioxidant, and stir until completely dissolved to prepare a lead-free tin-based perovskite precursor solution;
[0010] The molar ratio of the formamidinium iodide, stannous iodide, formamidinium iodide salt and stannous fluoride is 0.9:1:0.1:0.1;
[0011] Step 2: On the ITO transparent conductive glass substrate on which a hole transport layer has been deposited, spin-coat and deposit the lead-free tin-based perovskite
[0012] precursor solution to obtain a lead-free tin-based perovskite thin film;
[0013] Step 3: Adopt a gradient annealing method to obtain a three-dimensional lead-free tin-based perovskite thin film.
[0014] The polar organic solvent is one or two of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The concentration of the lead-free tin-based perovskite precursor solution is 0.7-0.9 mmol / mL.
[0015] In the step 2, a one-step anti-solvent spin-coating method is used to deposit the tin-based perovskite thin film.
[0016] The anti-solvent is chlorobenzene.
[0017] In the step 3 gradient annealing method, after low-temperature annealing at 40 °C for 1 minute, it is transferred to continue high-temperature annealing at 100 °C for 10 minutes.
[0018] A method for preparing a lead-free tin-based perovskite solar cell by using the prepared three-dimensional lead-free tin-based perovskite thin film, characterized in that the steps are as follows:
[0019] S1: Spin-coat the hole transport material PEDOT:PSS on a clean ITO transparent conductive glass substrate to prepare a hole transport layer;
[0020] S2: Obtain a lead-free tin-based perovskite thin film on the ITO transparent conductive glass substrate with a hole transport layer PEDOT:PSS deposited in step S1 according to a preparation method of a three-dimensional structure lead-free tin-based perovskite thin film;
[0021] S3: Prepare an electron transport layer C60 on the lead-free tin-based perovskite thin film;
[0022] S4: Sequentially prepare a hole blocking layer BCP and a metal Ag electrode on the electron transport layer.
[0023] The hole transport layer PEDOT:PSS in S1 adopts the solution spin-coating method.
[0024] The electron transport layer C60, hole blocking layer BCP and metal Ag electrode in S3 and S4 are prepared by vacuum evaporation.
[0025] As a further limitation of the present invention, the hole transport layer PEDOT:PSS in S1 adopts the solution spin-coating method, the annealing temperature is 150 °C, the annealing time is 20 min, the electron transport layer C60 in S3 adopts the vacuum evaporation method, the thickness is 300 nm, the thickness of the hole blocking layer BCP in S4 is 60 nm, and the thickness of the metal Ag electrode is 120 nm.
[0026] Beneficial effects
[0027] A preparation method of a three-dimensional structure lead-free tin-based perovskite thin film and a solar cell proposed by the present invention, a method for improving the stability of a tin-based perovskite solar cell by formamide iodide salt; includes the following steps: Mix formamide iodide salt, formamidinium iodide, stannous iodide, and stannous fluoride and dissolve them in a polar organic solvent, and obtain a precursor solution after mixing evenly; Spin-coat the precursor solution on a perovskite substrate and then perform annealing to obtain a tin-based perovskite thin film. The beneficial effects of the present invention include: The formamide iodide salt raw material used in the present invention is cheap, easy to prepare and obtain; The operation of the present invention is simple. By directly adding a small amount of formamide iodide salt to the tin-based perovskite precursor solution, a good perovskite thin film can be obtained, which is easy to meet the requirements of large-scale production; The efficiency of the lead-free tin-based perovskite solar cell modified by formamide iodide salt in the present invention is significantly improved, and the device efficiency does not decay after 6000 hours under the condition of exposing the unencapsulated device to oxygen.
[0028] Compared with the prior art, the present invention adopts the above technical solutions and has the following beneficial effects:
[0029] 1. The formamide iodide salt synthesis raw materials used in the present invention are cheap, easy to obtain, and the preparation process is simple;
[0030] 2. The operation of the present invention is simple. By introducing an appropriate proportion of formamidinium iodide salt into the perovskite precursor solution, a high-quality lead-free tin-based perovskite thin film can be obtained in one step, which is easy to meet the requirements of large-scale production and manufacturing.
[0031] 3. The stability of the tin-based perovskite solar cell device obtained by the present invention is significantly improved. Moreover, for the unencapsulated device, the efficiency does not decay after 6000 hours under the condition of exposure to oxygen. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 is a schematic structural diagram of the lead-free tin-based perovskite solar cell devices prepared in Example 1, Example 2, and Example 3 of the present invention;
[0033] Figure 2 is a dynamic light scattering diagram of the lead-free tin-based perovskite precursor solutions obtained in Example 2 and Comparative Example 1;
[0034] Figure 3 is an SEM diagram and a grain size distribution diagram of the lead-free tin-based perovskite thin films obtained in Example 2 and Comparative Example 1;
[0035] Figure 4 is an XRD diagram of the lead-free tin-based perovskite thin films obtained in Example 2 and Comparative Example 1;
[0036] Figure 5 is a J-V curve of the lead-free tin-based perovskite solar cell devices of the lead-free tin-based perovskite thin films obtained in Example 1, Example 2, Example 3, and Comparative Example 1;
[0037] Figure 6 is a curve showing the change of the photoelectric conversion efficiency over time of the tin-based perovskite solar cell devices obtained in Example 2 and Comparative Example 1 under the condition of being unencapsulated in a nitrogen environment. DETAILED DESCRIPTION OF THE INVENTION
[0038] The present invention will be further described below in combination with examples and drawings:
[0039] The content of the present invention will be further described in detail below in combination with the drawings and specific examples. The following examples are all based on the preparation of an inverted planar tin-based perovskite solar cell for the purpose of fully understanding the present invention. The specific steps are as follows:
[0040] The preparation method of the perovskite substrate of the present invention is as follows:
[0041] Step 1) The etched ITO transparent conductive glass is ultrasonically cleaned in ethanol, ultrapure water plus cleaning agent, ultrapure water, and ethanol for 30 minutes each. After drying with nitrogen, it is placed in an oven for baking to obtain a clean ITO substrate.
[0042] Step 2) Treat the cleaned ITO substrate in step 1) with ultraviolet ozone for 20 minutes.
[0043] Step 3) Take 36 μL of the hole transport material PEDOT:PSS and drop it onto the ITO substrate treated in step 2) with a pipette. After spinning at a speed of 5000 revolutions per minute for 50 seconds, place the ITO substrate coated with PEDOT:PSS in an oven at 150 °C for annealing for 20 min.
[0044] Example 1:
[0045] S1 Dissolve formamidinium iodide, methylammonium iodide, stannous iodide, and stannous fluoride in a molar ratio of 0.05:0.95:1:0.1 in 1 mL of dimethyl sulfoxide solvent, and stir at 25 °C for 4 hours until completely dissolved to prepare a lead-free tin-based perovskite precursor solution with a concentration of 0.7 mmol / mL.
[0046] S2 Take 60 μL of the lead-free tin-based perovskite precursor solution prepared in step S1 and drop it onto the treated substrate. Spin-coat at a speed of 5000 revolutions per minute for 60 seconds. Add 400 μL of chlorobenzene at the 45th second. After the spin-coating is completed, anneal at 40 °C for 1 minute, and then directly transfer it to an oven at 100 °C for annealing for 10 minutes to obtain a lead-free tin-based perovskite thin film.
[0047] S3 Using the vacuum thermal evaporation method, sequentially evaporate 30 nm of C60, 6 nm of BCP, and 120 nm of metal electrode Ag on the lead-free tin-based perovskite thin film to obtain a tin-based perovskite solar cell. The device structure is as Figure 1 .
[0048] In order to detect the performance of the lead-free tin-based perovskite solar cell, the following steps were also carried out:
[0049] S4 Under standard test conditions (AM1.5G illumination), the photoelectric conversion efficiency of the solar cell device prepared in this example is 6.11%, the open-circuit voltage is 0.43 V, the short-circuit current is 21.00 mA / cm2, and the fill factor is 67.96%.
[0050] Example 2:
[0051] The method of this comparative example is the same as that of Example 1, except that the molar ratio of formamidinium iodide, methylammonium iodide, stannous iodide, and stannous fluoride in the precursor solution is changed to 0.1:0.9:1:0.1. It can be seen from the Figure 2 dynamic light scattering diagram that the micelle size increases significantly before and after adding formamidinium iodide salt to the precursor solution; it can be seen from the Figure 3 SEM diagram that the introduction of formamidinium iodide salt reduces the generation of holes, improves the film morphology, improves the film quality, and at the same time the grain size increases significantly. After statistics, the average particle size increases from 237 nm to 322 nm; fromFigure 4 It can be seen from the XRD pattern of that the introduction of formamidinium iodide does not affect the crystal form of perovskite, and at the same time enhances the crystallization characteristics of the film. Under standard test conditions (AM1.5G illumination), the photoelectric conversion efficiency of the solar cell device prepared in this example is 7.71%, the open-circuit voltage is 0.54V, the short-circuit current is 20.69mA / cm2, and the fill factor is 69.06%.
[0052] Example 3:
[0053] The method of this comparative example is the same as that of Example 1, except that the molar ratio of formamidinium iodide, formamidinium iodide, stannous iodide and stannous fluoride in the precursor solution becomes 0.15:0.85:1:0.1. After adding the formamidinium iodide salt, the film morphology is improved and the device efficiency is increased. Under standard test conditions (AM1.5G illumination), the photoelectric conversion efficiency of the solar cell device prepared in this example is 7.34%, the open-circuit voltage is 0.51V, the short-circuit current is 20.73mA / cm2, and the fill factor is 69.57%.
[0054] Comparative Example 1:
[0055] The method of this comparative example is the same as that of Examples 1-3, except that the formamidinium iodide salt is not added to the precursor solution. Figure 3 a The scanning electron microscope photos of the comparative example provided show that the grain sizes of the perovskite film without the addition of formamidinium iodide salt are inconsistent, there are obvious holes, and the grain sizes are small. Under standard test conditions (AM1.5G illumination), the photoelectric conversion efficiency of the solar cell device prepared in this comparative example is 5.33%, the open-circuit voltage is 0.52V, the short-circuit current is 18.56mA / cm2, and the fill factor is 55.10%. From Figure 6 It can be found that under the same placement conditions, the tin-based perovskite battery without the addition of formamidinium iodide salt decays extremely and fails when exposed to trace amounts of oxygen (200ppm), indicating that its stability is much worse than that of the tin-based perovskite battery with the addition of formamidinium iodide salt.
[0056] Table 1:
[0057]
[0058] The present invention is not limited to the specific technical solutions described in the above embodiments. Any technical solutions formed by equivalent replacement are within the protection scope required by the present invention.
Claims
1. A method for preparing a lead-free tin-based perovskite thin film with a three-dimensional structure, characterized in that The steps are as follows: Step 1: Prepare a precursor solution; dissolve formamidinium iodide, stannous iodide, formamide iodide in a polar organic solvent, and simultaneously add stannous fluoride as an antioxidant, and stir until completely dissolved to prepare a lead-free tin-based perovskite precursor solution; The molar ratio of the formamidinium iodide, stannous iodide, formamide iodide, and stannous fluoride is 0.9:1:0.1:0.1; Step 2: On the ITO transparent conductive glass substrate on which a hole transport layer has been deposited, spin-coat and deposit the lead-free tin-based perovskite precursor solution to obtain a lead-free tin-based perovskite thin film; Step 3: Adopt a gradient annealing method to obtain a three-dimensional lead-free tin-based perovskite thin film.
2. The preparation method of the lead-free tin-based perovskite thin film with a three-dimensional structure according to claim 1, wherein: The concentration of the lead-free tin-based perovskite precursor solution is 0.7 - 0.9 mmol / mL.
3. The preparation method of the lead-free tin-based perovskite thin film with a three-dimensional structure according to claim 1, characterized in that: The polar organic solvent is one or two of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).
4. The preparation method of the lead-free tin-based perovskite thin film with a three-dimensional structure according to claim 1, characterized in that: In Step 2, a one-step anti-solvent spin-coating method is used to deposit the tin-based perovskite thin film.
5. The preparation method of the lead-free tin-based perovskite thin film with a three-dimensional structure according to claim 4, wherein: The anti-solvent is chlorobenzene.
6. The preparation method of the lead-free tin-based perovskite thin film with a three-dimensional structure according to claim 1, characterized in that: In the gradient annealing method of Step 3, after low-temperature annealing at 40°C for 1 minute, it is transferred to continue high-temperature annealing at 100°C for 10 minutes.
7. A method for preparing a lead-free tin-based perovskite solar cell using a three-dimensional structured lead-free tin-based perovskite thin film prepared by any one of claims 1 to 6, characterized in that The steps are as follows: S1: Spin-coat a hole transport material PEDOT:PSS on a clean ITO transparent conductive glass substrate to prepare a hole transport layer; S2: A lead-free tin-based perovskite thin film obtained by the preparation method described in Claims 1 - 4 on the ITO transparent conductive glass substrate on which the hole transport layer PEDOT:PSS is deposited in Step S1; S3: Prepare an electron transport layer C60 on the lead-free tin-based perovskite thin film; S4: Sequentially prepare a hole blocking layer BCP and a metal Ag electrode on the electron transport layer.
8. The method for preparing a lead-free tin-based perovskite solar cell using the lead-free tin-based perovskite film with a three-dimensional structure according to claim 7, characterized in that: The hole transport layer PEDOT:PSS in S1 adopts a solution spin-coating method.
9. A method for preparing a lead-free tin-based perovskite solar cell using a lead-free tin-based perovskite thin film with a three-dimensional structure according to claim 7, characterized in that: The electron transport layer C60, hole blocking layer BCP, and metal Ag electrode in S3 and S4 are prepared by vacuum evaporation.