Perovskite solar cell regulated by a pyrimidine derivative and preparation method thereof

Abstract

The present application relates to the technical field of solar cells, in particular to a kind of perovskite solar cell regulated by pyrimidine derivative and preparation method thereof, comprising the following steps: 1, clean conductive substrate;2, deposit electron transport layer on the conductive substrate;3, deposit lead iodide film on the electron transport layer: after coating lead iodide precursor solution on the electron transport layer, obtain by annealing, wherein the lead iodide precursor solution contains pyrimidine derivative, and the structural formula of the pyrimidine derivative is as shown in formula 1;4, deposit perovskite light-absorbing layer on the lead iodide film;5, deposit passivation layer on the perovskite light-absorbing layer;6, deposit hole transport layer on the passivation layer;7, deposit electrode on the hole transport layer.The present application can directionally induce perovskite to form optimal crystal orientation, while reducing lead iodide residue, and finally obtain perovskite solar device with higher photoelectric conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a perovskite solar cell regulated by a pyrimidine derivative and a preparation method thereof. Background Art

[0002] With the rapid development of the global economy, energy demand continues to increase, and the impact on the environment is becoming increasingly severe. Traditional fossil fuels, such as coal, oil, and natural gas, produce large amounts of greenhouse gases such as carbon dioxide when burned, exacerbating global climate change. Photovoltaic energy is a clean energy source that produces virtually no greenhouse gas emissions during power generation, helping to reduce the risks of global climate change. Against this backdrop, the development of new energy sources, particularly photovoltaic technology, has become a crucial component.

[0003] In recent years, perovskite solar cells have become one of the most promising photovoltaic materials due to their unique properties, including strong light absorption coefficient, excellent charge mobility, low exciton binding energy, long carrier diffusion length, easily tunable band gap, and simple fabrication process. Although the power conversion efficiency of certified PSCs has increased from 3.8% in 2009 to 26.7% today, issues such as fabrication costs and long-term device stability continue to hinder their commercialization.

[0004] Perovskite layers are typically prepared via a one-step antisolvent or two-step sequential deposition method. The two-step method offers excellent operability and great commercial potential due to the ability to pre-adjust the PbI2 template. The orientation of the perovskite crystal ultimately affects the quality and performance of the device, and previous reports have demonstrated that the (001) crystal plane exhibits excellent optical properties and is the optimal orientation through theoretical calculations. However, the heavy reliance on the growth of perovskite crystals on the PbI2 matrix and the penetration of halide cations means that the perovskite particles can easily become disordered and introduce unnecessary non-radiative recombination sites, which greatly affects the photovoltaic efficiency and stability of PSCs. Therefore, in the typical two-step sequential deposition method, the growth of the PbI2 film is crucial for the subsequent intercalation of halide cations and the transformation to the perovskite phase.

[0005] Existing technologies primarily improve the morphology of lead iodide by introducing additives, further promoting the second-step reaction to form perovskite. These improvements primarily improve the size, morphology, and crystallinity of the perovskite grains, but they fail to orient the perovskite along optimal crystal planes, leaving a significant amount of residual PbI2, and the additives used are expensive. Therefore, two major technical challenges remain: how to regulate the growth morphology of the PbI2 film to facilitate the subsequent intercalation of halide cations, ensuring a full reaction and reducing residual PbI2; and how to induce the formation of perovskite crystals with good optical activity. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention provides a perovskite solar cell controlled by a pyrimidine derivative and a method for preparing the same. By introducing a relatively low-cost pyrimidine derivative with a pyrimidine ring as its backbone into a PbI2 precursor solution, the present invention enables a more complete second-step reaction, directionally inducing the perovskite to form an optimal crystal orientation while reducing lead iodide residue, ultimately resulting in a perovskite solar device with higher photoelectric conversion efficiency.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a perovskite solar cell regulated by a pyrimidine derivative, comprising the following steps:

[0009] 1. Clean the conductive substrate;

[0010] 2. depositing an electron transport layer on the conductive substrate;

[0011] 3. Depositing a lead iodide thin film on the electron transport layer: coating a lead iodide precursor solution on the electron transport layer and then annealing the solution, wherein the lead iodide precursor solution contains a pyrimidine derivative, and the structural formula of the pyrimidine derivative is as shown in Formula 1, wherein A, B, C, and D are all selected from one or more combinations of F, Cl, Br, I, hydrogen, amino, carboxyl, hydroxyl, aldehyde, ester, phosphate, and sulfonamide:

[0012]

[0013] 4. depositing a perovskite light-absorbing layer on the lead iodide film;

[0014] 5. Depositing a passivation layer on the perovskite light absorbing layer;

[0015] 6. Depositing a hole transport layer on the passivation layer;

[0016] 7. Depositing an electrode on the hole transport layer.

[0017] In some embodiments of the present invention, the structure of the pyrimidine derivative may be any one or more of the following formulas 2 to 10:

[0018]

[0019]

[0020] Preferably, the conductive substrate includes a substrate and a transparent conductive metal oxide deposited on the substrate, and the substrate is selected from any one of glass, quartz, flexible PET or flexible PEN; the transparent conductive metal oxide is indium tin oxide (ITO) or fluorine-doped tin oxide (FTO).

[0021] Preferably, the material of the electron transport layer includes but is not limited to tin dioxide, titanium dioxide, zinc oxide, PCBM, and C60.

[0022] Preferably, in the process of depositing the electron transport layer in step 2, the annealing temperature is 100-150° C. and the time is 10-30 minutes.

[0023] Preferably, before depositing the lead iodide thin film on the electron transport layer, the transparent conductive substrate with the electron transport layer needs to be subjected to ultraviolet ozone treatment.

[0024] Preferably, in the step 3, the solvent for preparing the lead iodide precursor solution is selected from one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone (DMPU), 1,3-dimethyl-2-imidazolidinone (DMI), diphenyl sulfoxide (DPSO), formamide (NMF), 2-methoxyethanol (2-ME), ethyl acetate (EtAc), butyl acetate (BtAc), acetonitrile (ACN), γ-butyrolactone (GBL) and γ-valerolactone (GVL), acetic acid, acetone, nitromethane, aniline, methanol, and ethylene glycol.

[0025] Preferably, the mass volume concentration of the pyrimidine derivative in the lead iodide precursor solution is 0.0012 to 0.02 g / mL. In some embodiments of the present invention, the mass volume concentration of the pyrimidine derivative in the lead iodide precursor solution is any one of 0.0012 g / mL, 0.005 g / mL, 0.02 g / mL, or a value in between.

[0026] Preferably, the annealing temperature in step 3 is 70° C. and the annealing time is 5 to 60 seconds.

[0027] Preferably, the coating speed in step 3 is 1500 to 3000 rpm.

[0028] Preferably, the amount of the lead iodide precursor solution used in step 3 is 10 to 50 μL.

[0029] Preferably, the material of the perovskite light absorbing layer includes but is not limited to MAPbI3, (FAPbI3) 1-x (MAPbBr3) x 、(FAPbI3) 1-x (MAPbCl3) x 、FAPbI3、MA x FA 1-x PbI3、FA 1-x Cs x Any one or more of PbI3.

[0030] Preferably, the step 4 specifically comprises: coating a halide cation solution on the lead iodide film and then annealing the film.

[0031] More preferably, the annealing temperature is 100-150° C., and the annealing time is 5-30 minutes.

[0032] More preferably, the coating speed is 2000 rpm to 4000 rpm.

[0033] Preferably, the passivation layer material is selected from one or more of phenylethylammonium iodide (PEAI) and isobutylammonium bromide (iBABr).

[0034] Preferably, the raw material of the hole transport layer is selected from one or more of tert-butylpyridine (TBP), lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI), tris(2-(1H-pyrazol-1-yl)pyridine) (Co)-doped [N,N-bis(4-methoxyphenyl)amino]spirobifluorene (Spiro-MeOTAD), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), PTAA, P3HT, and nickel oxide.

[0035] Preferably, the electrode is made of a conductive metal material, which is selected from any one of gold Au, silver Ag, and copper Cu, and has a thickness of more than 60 nm.

[0036] Preferably, the preparation of the lead iodide thin film, the perovskite light-absorbing layer, the passivation layer and the hole transport layer needs to be carried out under a protective atmosphere.

[0037] Preferably, the deposition method of the perovskite light-absorbing layer can be a solution method, a vacuum co-evaporation method, a vacuum continuous deposition method, a vacuum and solution combination method, or any process combination, etc. The solution method includes solution spin coating, solution blade coating, solution spraying, and slit coating.

[0038] In a second aspect, the present invention provides a perovskite solar cell prepared by the preparation method.

[0039] The beneficial effects of the present invention are:

[0040] The present invention prepares perovskite solar cells using a two-step sequential deposition method, wherein when preparing a lead iodide film, a relatively low-cost pyrimidine derivative with a pyrimidine ring as a skeleton is introduced into a lead iodide precursor solution. The pyrimidine derivative is an environmentally friendly, low-cost additive that can improve stability. The pyrimidine derivative utilizes its conjugated structure, the lone pair electrons contained in the nitrogen atom, and the advantage of being able to introduce other groups to achieve multi-site passivation to adjust the morphology and crystallization of the lead iodide film, making the second-step reaction more complete, directionally inducing the perovskite to form an optimal crystal orientation, while reducing lead iodide residue, and ultimately obtaining a perovskite solar device with higher photoelectric conversion efficiency.

[0041] As an environmentally friendly, low-cost additive that can improve stability, pyrimidine derivatives are expected to improve the competitiveness of perovskite solar cells in the market and promote the development and application of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a morphology image of the lead iodide thin film obtained in Example 1;

[0043] Figure 2 is a morphology image of the lead iodide thin film obtained in Example 2;

[0044] Figure 3 This is a morphology image of the lead iodide thin film obtained in Example 3;

[0045] Figure 4 is a morphology diagram of the lead iodide thin film obtained in Comparative Example 1;

[0046] Figure 5 XRD characterization diagrams of the perovskite films prepared in Example 1 and Comparative Example 1;

[0047] Figure 6 for Figure 5 Quantitative comparison of XRD peak intensity;

[0048] Figure 7 1 is a JV curve diagram of the solar cell of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the technical solution of the invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0050] Example 1

[0051] In this embodiment, ITO is selected as the transparent conductive substrate, SnO2 is selected as the electron transport layer material, FAPbI3 is selected as the perovskite light absorption layer material, iBABr is selected as the passivation layer material, Spiro-OMeTAD is selected as the hole transport layer material, the electrode material is metallic Ag, and the pyrimidine derivative is 2-chloropyrimidine, with the structural formula being:

[0052]

[0053] This embodiment provides a method for preparing a perovskite solar cell regulated by a pyrimidine derivative, and the steps are as follows:

[0054] Preparation of preliminary solution:

[0055] Preparation of lead iodide precursor: 0.6915 g PbI2, 0.0092 g RbCl (rubidium chloride), and 0.0012 g 2-chloropyrimidine were dissolved in 1 mL of a mixed solvent of DMF and DMSO (volume ratio of 9:1), heated at 70 ° C for 2 hours and stirred until completely dissolved. Then, a 0.45 μm filter element was used to filter out larger particles in the solution to obtain a lead iodide precursor solution.

[0056] Preparation of halide cation solution: Dissolve 0.0900 g FAI and 0.0090 g MACl in 1 mL IPA (isopropyl alcohol) solution and shake until completely dissolved.

[0057] Preparation of the passivation layer solution: Dissolve 0.0030 g of iBABr in 1 mL of IPA solution and shake until completely dissolved.

[0058] Preparation of LiTFSI (lithium bis(trifluoromethanesulfonyl imide)) solution: 520 mg of LiTFSI was dissolved in 1 mL of ACN to obtain a LiTFSI solution with a concentration of 520 mg / mL.

[0059] Preparation of Co salt (tris(2-(1H-pyrazol-1-yl)pyridine)) solution: 300 mg of Co salt was dissolved in 1 mL of ACN to obtain a Co salt solution with a concentration of 300 mg / mL.

[0060] Preparation of spiro-OMeTAD solution: 101.2 mg of spiro OMeTAD was dissolved in 1 mL of chlorobenzene solution to obtain a spiro solution. 24.5 μL of Li TFSI solution, 40.3 μL of TBP, and 49 μL of Co salt solution were added to 1 mL of the spiro solution to form a doped spiro solution. The solution was then filtered through a 0.45 μm filter cartridge to remove larger particles to obtain a spiro-OMeTAD solution.

[0061] Preparation steps:

[0062] 1. Pretreatment of the conductive substrate: The ITO conductive glass substrate was cleaned with detergent, ultrapure water, acetone, and isopropyl alcohol for 30 minutes each in sequence. The cleaning method was ultrasonic cleaning, followed by drying with a nitrogen gun and placing it in a UV ozone processor for 30 minutes for standby use.

[0063] 2. Preparation of electron transport layer: 40 μL of SnO2 colloidal solution was spin-coated on the ITO substrate at a spin coating rate of 2000 rpm for 30 seconds, followed by annealing at 150°C for 30 minutes to form an electron transport layer;

[0064] 3. Treat the transparent conductive substrate with the electron transport layer with UV ozone for 5 to 30 minutes;

[0065] 4. Preparation of lead iodide film: Under nitrogen atmosphere, 30 μL of the prepared lead iodide precursor solution was spin-coated on the substrate coated with the electron transport layer. After spin coating, the solution was allowed to stand for 2 minutes and then annealed for crystallization. The annealing temperature was 70°C, the annealing time was 10 seconds, and the spin coater speed was 1500 rpm for 40 seconds.

[0066] 5. Preparation of a perovskite light-absorbing layer: Under a nitrogen atmosphere, 50 μL of the prepared halide cation solution was spin-coated on the lead iodide film obtained in step 4 at a rate of 2000 rpm for 30 seconds. The film was then annealed and crystallized in a simple glove box ventilated with dry air at a temperature of 150°C for 15 minutes to obtain a perovskite film.

[0067] 6. Preparation of the passivation layer: In a nitrogen environment, spin-coat 30 μL of the prepared passivation layer solution on the perovskite film at a spin coating rate of 4000 rpm and anneal for 1 minute to obtain a perovskite film modified with the passivation layer;

[0068] 7. Preparation of hole transport layer: In a nitrogen environment, spin-coat 25 μL of the prepared Spiro-OMeTAD solution on the passivation layer at a spin coating rate of 4500 rpm for 25 seconds to prepare a hole transport layer;

[0069] 8. A 100 nm thick Ag electrode was formed on the surface of the hole transport layer by thermal evaporation.

[0070] Example 2

[0071] The preparation method is the same as that of Example 1, except that the mass of the pyrimidine derivative (2-chloropyrimidine) added during the preparation of the lead iodide precursor is 0.0050 g.

[0072] Example 3

[0073] The preparation method is the same as that of Example 1, except that the mass of the pyrimidine derivative (2-chloropyrimidine) added during the preparation of the lead iodide precursor is 0.0200 g.

[0074] Example 4

[0075] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0076]

[0077] Example 5

[0078] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0079]

[0080] Example 6

[0081] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0082]

[0083] Example 7

[0084] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0085]

[0086] Example 8

[0087] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0088]

[0089] Example 9

[0090] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0091]

[0092] Example 10

[0093] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0094]

[0095] Example 11

[0096] The preparation method is the same as that of Example 1, except that the structural formula of the pyrimidine derivative is:

[0097]

[0098] Comparative Example 1

[0099] The preparation method is the same as that of Example 1, except that no pyrimidine derivative (2-chloropyrimidine) is added during the preparation of the lead iodide precursor.

[0100] Effect Example 1 Morphology Characterization of Lead Iodide Thin Film

[0101] The morphology of the lead iodide thin films obtained in step 5 of Examples 1 to 3 and Comparative Example 1 was characterized, and the SEM images are shown in FIG. Figures 1 to 4 . Figure 4 The morphology of the lead iodide film obtained in Comparative Example 1 is shown in FIG. 1 , where the lead iodide is distributed in an island-like manner and no holes are formed. Figure 1 This is a morphology diagram of the lead iodide film obtained in Example 1. The lead iodide morphology is a loose porous structure. Figure 2 This is a morphology diagram of the lead iodide film obtained in Example 2. Compared with Comparative Example 1, although the morphology of the lead iodide film has an island-like distribution, a small amount of pore structures can be observed in local areas. Figure 3 Figure 3 is a morphology of the lead iodide film obtained in Example 3. Compared with Comparative Example 1, the island-like distribution of lead iodide disappears, and obvious holes are observed. However, the number of holes in the lead iodide film in Example 3 is relatively small compared with Example 1. This difference in the lead iodide morphology between the example and the comparative example leads to different degrees of reaction between halide cations and lead iodide. In addition, the loose and porous structure allows the perovskite to grow along the optimal crystal plane.

[0102] Effect Example 2 XRD Characterization of Perovskite Film

[0103] The XRD characterization diagrams of the perovskite films prepared in step 5 of Example 1 and Comparative Example 1 are shown in FIG. Figure 5 , the symbol * represents the diffraction peak of lead iodide, and the diffraction peaks of different crystal planes of perovskite are marked in the figure. It can be seen that compared with Comparative Example 1, the perovskite film modified with 2-chloropyrimidine in the present invention has a lower lead iodide residue and a higher perovskite crystallinity, and it can be clearly seen that, relative to Comparative Example 1, the (111) crystal plane of Example 1 is significantly lower than the (002) crystal plane. This shows that the introduction of pyrimidine derivatives in the present invention can directionally induce the perovskite to grow along the optimal crystal plane (001) and inhibit the growth of the (111) crystal direction, thereby obtaining better device efficiency and stability.

[0104] Figure 6 Yes Figure 5 From the quantitative comparison diagram of the XRD peak intensity, it can be seen that compared with Comparative Example 1, the perovskite film modified with 2-chloropyrimidine in the present invention has a lower lead iodide residue and a higher perovskite crystallinity, and it can be clearly seen that relative to Comparative Example 1, the (111) crystal plane of Example 1 is significantly lower than the (002) crystal plane.

[0105] Effect Example 3 Photovoltaic Performance Test of Solar Cells

[0106] The photovoltaic characteristics of the solar cells of Example 1 and Comparative Example 1 were tested under nitrogen atmosphere and AM1.5 illumination. The JV curves are shown in FIG. Figure 7 As shown in the figure, compared with comparative example 1, the performance parameters of the perovskite solar cell modified with 2-chloropyrimidine are improved. The power conversion efficiency (PCE) of the device reaches 25.22%, while the PCE of comparative example 1 can only reach 23.97%. Among them, 2-chloropyrimidine has the most obvious improvement on the fill factor FF.

[0107] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite solar cell regulated by a pyrimidine derivative, characterized in that: The following steps are involved:

1. Clean the conductive substrate; 2. depositing an electron transport layer on the conductive substrate; 3. Depositing a lead iodide thin film on the electron transport layer: coating a lead iodide precursor solution on the electron transport layer and then annealing the solution, wherein the lead iodide precursor solution contains a pyrimidine derivative, and the structural formula of the pyrimidine derivative is as shown in Formula 1, wherein A, B, C, and D are all selected from one or more combinations of F, Cl, Br, I, hydrogen, amino, and ester groups:

4. coating a halide cation solution on the lead iodide film and then annealing to obtain a perovskite light-absorbing layer; 5. Depositing a passivation layer on the perovskite light absorbing layer; 6. Depositing a hole transport layer on the passivation layer; 7. Depositing an electrode on the hole transport layer.

2. The preparation method according to claim 1, characterized in that The structure of the pyrimidine derivative is any one or more of the following formulas 2 to 10:

3. The preparation method according to claim 1 or 2, characterized in that In the step 3, the solvent for preparing the lead iodide precursor solution is selected from one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone (DMPU), 1,3-dimethyl-2-imidazolidinone (DMI), diphenyl sulfoxide (DPSO), formamide (NMF), 2-methoxyethanol (2-ME), ethyl acetate (EtAc), butyl acetate (BtAc), acetonitrile (ACN), γ-butyrolactone (GBL) and γ-valerolactone (GVL), acetic acid, acetone, nitromethane, aniline, methanol, and ethylene glycol.

4. The preparation method according to claim 1, characterized in that The mass volume concentration of the pyrimidine derivative in the lead iodide precursor solution is 0.0012-0.02 g / mL.

5. The preparation method according to claim 1, characterized in that In step 3, the annealing temperature is 70° C. and the annealing time is 5 to 60 seconds.

6. The preparation method according to claim 1 or 4, characterized in that The amount of the lead iodide precursor solution used in step 3 is 10 to 50 μL.

7. The preparation method according to claim 1, characterized in that The materials of the perovskite light absorbing layer include but are not limited to MAPbI3, (FAPbI3) 1-x (MAPbBr3) x 、(FAPbI3) 1-x (MAPbCl3) x 、FAPbI3、MA x FA 1-x PbI3、FA 1-x Cs x Any one or more of PbI3.

8. The preparation method according to claim 1, characterized in that The annealing temperature in step 4 is 100-150° C., and the annealing time is 5-30 minutes.

9. A perovskite solar cell prepared by the preparation method according to any one of claims 1 to 8.

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