Pyrimidine derivative regulated perovskite solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, in particular to a pyrimidine derivative regulated perovskite solar cell and a preparation method thereof, and the method comprises the following steps: 1, cleaning a conductive substrate; 2, depositing an electron transport layer on the conductive substrate; 3, a lead iodide film is deposited on the electron transport layer, the electron transport layer is coated with a lead iodide precursor solution, then annealing is carried out, the lead iodide film is obtained, the lead iodide precursor solution contains a pyrimidine derivative, and the structural formula of the pyrimidine derivative is shown in the formula 1; 4, depositing a perovskite light absorption layer on the lead iodide thin film; 5, depositing a passivation layer on the perovskite light absorption layer; 6, depositing a hole transport layer on the passivation layer; and 7, depositing an electrode on the hole transport layer. According to the invention, the perovskite can be directionally induced to form the optimal crystal orientation, meanwhile, the residual lead iodide is reduced, and finally, the perovskite solar device with higher photoelectric conversion efficiency is obtained.

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 serious. Traditional fossil energy, such as coal, oil and natural gas, will produce a large amount of greenhouse gases such as carbon dioxide after combustion, exacerbating global climate change. Photovoltaic energy is a clean energy that produces almost no greenhouse gas emissions during the power generation process, which helps reduce the risk of global climate change. In this context, the development of new energy, especially photovoltaic technology, has become the most critical link.

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

[0004] Perovskite layers are usually prepared by a one-step antisolvent or two-step sequential deposition method. The two-step method has excellent operability and great commercialization potential because the PbI2 template can be pre-adjusted. The orientation of perovskite crystals ultimately affects the quality and performance of the device. Through theoretical calculations, previous reports have demonstrated that the (001) crystal plane has good optical properties and is the optimal orientation. However, the heavy reliance on the growth of perovskite crystals on the PbI2 matrix and the penetration of halide cations means that 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 PbI2 film is crucial for the subsequent intercalation of halide cations and the transformation to the perovskite phase.

[0005] The existing technology mainly improves the morphology of lead iodide by introducing additives, and further promotes the second step reaction to generate perovskite, which mainly improves the size, morphology, and crystallinity of perovskite grains, but does not induce the perovskite to grow along the optimal crystal plane, and there is still a lot of PbI2 residue and the cost of the additives used is high. Therefore, how to regulate the growth morphology of PbI2 film and facilitate the subsequent intercalation of halide cations to make the reaction sufficient, reduce the residual PbI2 residue, and how to induce the formation of perovskite crystal orientation with good optical activity have become two major technical issues. Summary of the invention

[0006] In order to solve the defects in the prior art, the present invention provides a perovskite solar cell regulated by a pyrimidine derivative and a preparation method thereof. The present invention introduces a low-cost pyrimidine derivative with a pyrimidine ring as a skeleton into a PbI2 precursor solution, so that the second step reaction is more complete, the perovskite is directionally induced to form an optimal crystal orientation, and the lead iodide residue is reduced, and finally a perovskite solar device with higher photoelectric conversion efficiency is obtained.

[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 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, 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 comprises a substrate and a transparent conductive metal oxide deposited on the substrate, 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 annealing time is 10-30 minutes.

[0023] Preferably, before depositing the lead iodide 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 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-pyrimidone (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 0.0012-0.02 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 between the two.

[0026] Preferably, in step 3, the annealing temperature is 70° C. and the 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(trifluoromethanesulfonate imide) (Li-TFSI), tris(2-(1H-pyrazol-1-yl)pyridine) (Co)-doped [N,N-di(4-methoxyphenyl)amino]spirobifluorene (Spiro-MeOTAD), 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), PTAA, P3HT, and nickel oxide.

[0035] Preferably, the electrode is a conductive metal material, and the conductive metal material 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 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 a solution spin coating method, a solution scraping method, a solution spray coating method, and a slit coating method.

[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 adopts a two-step sequential deposition method to prepare a perovskite solar cell, 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, and the pyrimidine derivative is an environmentally friendly, low-cost additive that can improve stability. The morphology and crystallization of the lead iodide film are adjusted by utilizing the advantages of its conjugated structure, the lone pair electrons contained in the nitrogen atom, and the ability to introduce other groups to achieve multi-site passivation, so that the second step reaction is more sufficient, the perovskite is directionally induced to form an optimal crystal orientation, and the lead iodide residue is reduced, and finally a perovskite solar device with higher photoelectric conversion efficiency is obtained.

[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 film obtained in Example 1;

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

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

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

[0046] Figure 5 XRD characterization diagram of the perovskite film 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 cells 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 a transparent conductive substrate, SnO2 is selected as an electron transport layer material, FAPbI3 is selected as a perovskite light absorption layer material, iBABr is selected as a passivation layer material, Spiro-OMeTAD is selected as a hole transport layer material, the electrode material is metal Ag, and the pyrimidine derivative is 2-chloropyrimidine, and the structural formula is:

[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] Preliminary solution preparation:

[0055] Preparation of lead iodide precursor: 0.6915g PbI2, 0.0092g RbCl (rubidium chloride), and 0.0012g 2-chloropyrimidine were dissolved in 1mL 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, and then filtered through a 0.45μm filter element to remove 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 (isopropanol) 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 it is completely dissolved.

[0058] Preparation of LiTFSI (lithium bis(trifluoromethanesulfonyl imide)) solution: 520 mg of Li TFSI was dissolved in 1 mL of ACN to obtain a Li TFSI 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, and a 0.45 μm filter element was used to filter out larger particles in the solution to obtain a spiro-OMeTAD solution.

[0061] Preparation steps:

[0062] 1. Pretreatment of the conductive substrate: The ITO conductive glass substrate is cleaned with a cleaning agent, ultrapure water, acetone, and isopropanol for 30 minutes each in turn. The cleaning method is ultrasonic cleaning, followed by drying with a nitrogen gun, and placed in a UV ozone processor for 30 minutes for standby use;

[0063] 2. Preparation of electron transport layer: 40 μL 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 ultraviolet ozone for 5 to 30 minutes;

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

[0066] 5. Preparation of perovskite light-absorbing layer: In a nitrogen environment, 50 μL of the prepared halide cation solution was spin-coated on the lead iodide film obtained in step 4 at a spin-coating rate of 2000 rpm for 30 seconds, and annealing and crystallization treatment was performed in a simple glove box with dry air at an annealing temperature of 150° C. for 15 minutes to obtain a perovskite film;

[0067] 6. Preparation of the passivation layer: In a nitrogen environment, 30 μL of the prepared passivation layer solution was spin-coated on the perovskite film at a spin-coating rate of 4000 rpm, and annealed for 1 minute to obtain a perovskite film modified with a 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] Embodiment 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 Examples 1 to 3 and Comparative Example 1 in step 5 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 . The lead iodide film has an island-like distribution and no holes are formed. Figure 1 This is a morphology picture 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 has an island-like distribution, a small amount of pore structures can be observed in local areas. Figure 3 The morphology of the lead iodide film obtained in Example 3 is shown in Figure 1. Compared with Comparative Example 1, the island distribution of lead iodide disappears, and obvious holes can be observed, but the number of holes in the lead iodide film in Example 3 is relatively small compared with Example 1. The difference in the morphology of lead iodide between the example and the comparative example will lead to different degrees of reaction between halide cations and lead iodide, and the loose and porous structure can make the perovskite grow along the optimal crystal plane.

[0102] Effect Example 2 XRD Characterization of Perovskite Film

[0103] The XRD characterization diagrams of the perovskite film prepared in step 5 of Example 1 and Comparative Example 1 are shown in 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 by 2-chloropyrimidine in the present invention has a lower residual lead iodide 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. It shows that the introduction of pyrimidine derivatives in the present invention can directionally induce the growth of perovskite 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 peak intensity of the XRD pattern, it can be seen that compared with Comparative Example 1, the perovskite film modified by 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 Photoelectric 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 by 2-chloropyrimidine are improved, and 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 only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope 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 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, 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:

4. Depositing a perovskite light-absorbing layer on the lead iodide film; 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-pyrimidone (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 step 4 specifically comprises: coating the lead iodide film with a halide cation solution and then annealing the solution.

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

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

Images