High-stability solar cell based on perovskite layer doping and preparation method

Abstract

The invention discloses a high-stability solar cell based on perovskite layer doping and a preparation method thereof. The preparation method comprises the following steps: 1) cleaning a substrate; 2) preparing an electron transport layer; (3) preparing a perovskite layer: adding PbI2 into a mixed solution of DMF (Dimethyl Formamide) and DMSO (Dimethylsulfoxide), and then adding potassium perfluorobutanesulfonate to obtain a PbI2 mixed solution; adding FAI and MACl into the IPA solution to obtain an FAI solution; depositing a PbI2 mixed solution and an FAI solution on the compact tin dioxide thin film through a two-step sequential deposition method to form a perovskite layer; the perovskite layer prepared by adopting the preparation method disclosed by the invention has fewer composite centers, and the prepared solar cell has higher efficiency and better stability.

Description

Technical Field

[0001] This invention relates to a highly stable solar cell based on perovskite layer doping and its fabrication method, belonging to the field of solar cell technology. Background Technology

[0002] Formamidinium (FAPbI3)-based solar cells have shown great potential due to their excellent thermal stability and ideal bandgap. However, the nonradiative recombination caused by the intrinsic quantum confinement effect of FAPbI3 limits the efficiency and stability of the cells. Notably, the crystallization process of perovskite thin films has a significant impact on defect formation, providing researchers with new insights. By optimizing the crystallization process, defect generation can be effectively reduced, thereby improving both efficiency and device stability. This has become an important research direction in the field of perovskite solar cells, and a deeper understanding of the relationship between perovskite film defects, crystallization modes, and efficiency will pave new paths for the future development of PSCs. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a high-stability solar cell based on perovskite layer doping and its preparation method. By doping the perovskite layer, the crystallization process of perovskite is intervened, the formation of defects is reduced, and the photoelectric conversion efficiency and operational stability of the perovskite solar cell are improved.

[0004] To achieve the above objectives, the present invention provides a method for fabricating a highly stable solar cell based on perovskite layer doping, comprising the following steps:

[0005] 1) Substrate cleaning: Using indium tin oxide glass as the substrate, clean the substrate;

[0006] 2) Preparation of electron transport layer: Tin dioxide precursor solution is coated on the substrate by spin coating, followed by high-temperature annealing and cooling to room temperature to form a dense tin dioxide film on the surface of indium tin oxide glass;

[0007] 3) Preparation of perovskite layer: PbI2 is added to a mixture of DMF and DMSO, and then potassium perfluorobutyl sulfonate is added to obtain a PbI2 mixed solution; FAI and MACl are added to an IPA solution to obtain a FAI solution; the PbI2 mixed solution and FAI solution are deposited on a dense tin dioxide film by a two-step sequential deposition method to form a perovskite layer;

[0008] 4) Preparation of hole transport layer: Prepare hole transport layer precursor solution, spin-coat it onto perovskite layer, and oxidize it;

[0009] 5) Electrode fabrication: Metal electrodes are deposited on the hole transport layer by vapor deposition.

[0010] As an improvement, the substrate is cut to a proper size in step 1), and then sequentially cleaned with deionized water, acetone and ethanol in an ultrasonic cleaner for 15 minutes, and then dried with nitrogen.

[0011] As an improvement, the preparation of the tin dioxide precursor solution in step 2) is as follows: SnO2 colloidal solution and deionized water are mixed at a mass ratio of 1:5.

[0012] As an improvement, the spin coating time of the tin dioxide precursor solution is 45 s, the annealing time is 30 min, and the annealing temperature is 150°C.

[0013] As an improvement, the preparation of the PbI2 mixed solution in step 3) is as follows: 550-650 mg of PbI2 is added to 1 mL of a mixed solution of DMF and DMSO, and potassium perfluorobutyl sulfonate is added to make the concentration of potassium perfluorobutyl sulfonate 0.5-1.5 mg / mL.

[0014] As an improvement, the volume ratio of DMF to DMSO in the mixed solution of DMF and DMSO is 950:50.

[0015] As an improvement, the spin coating time of the PbI2 mixed solution in step 3) is 20-40 s, the annealing time is 20-40 s, and the annealing temperature is 60-80°C.

[0016] As an improvement, the preparation of the FAI solution in step 3) is as follows: 50-70 mg of FAI and 10-15 mg of MACl are added to 1 mL of IPA solution.

[0017] The spin coating time of the FAI solution is 20-40 s, the annealing time is 10-15 min, and the annealing temperature is 140-150°C.

[0018] As an improvement, the preparation of the hole transport layer precursor solution in step 4) is as follows: 500-550 mg of bis(trifluoromethane) sulfonamide lithium salt is added to 1 mL of acetonitrile to obtain a bis(trifluoromethane) sulfonamide lithium salt solution.

[0019] 70-75 mg of Spiro-OMeTAD is added to a mixed solution of 1 mL of chlorobenzene, 17.5 microliters of bis(trifluoromethane) sulfonamide lithium salt solution, and 29 microliters of 4-tert-butylpyridine to obtain a hole transport layer precursor solution.

[0020] The spin coating time of the hole transport layer precursor solution is 20 s, and the oxidation time is 8 h.

[0021] The second aspect of the present application also provides a high-stability solar cell based on a perovskite layer doping, prepared by the preparation method, and the high-stability solar cell comprises:

[0022] a substrate;

[0023] an electron transport layer located on the surface of the substrate;

[0024] a perovskite layer located on the surface of the electron transport layer, the perovskite layer comprising a lead iodide film and a formamidinium iodide film, the lead iodide film being formed with a certain number of micropore structures on the surface of the dense film by introducing potassium perfluorobutyl sulfonate, and the pore diameter being 50-150 nm;

[0025] a hole transport layer located on the surface of the perovskite layer;

[0026] a metal electrode located on the surface of the hole transport layer.

[0027] Compared with the prior art, the high-stability solar cell based on a perovskite layer doping of the present application uses indium tin oxide glass as a conductive substrate, and a dense tin dioxide film is prepared on the substrate by high-temperature annealing of a tin dioxide precursor solution as an electron transport layer; then, a perovskite solution is coated by a spin coating method to form an alpha-FAPbI3 intermediate phase, and a high-quality perovskite film crystal is obtained by annealing treatment as an light-absorbing layer of the cell; Spiro-OMeTAD is used as a hole transport layer, and Ag is used as a metal electrode.

[0028] In the present application, potassium perfluorobutyl sulfonate is added to the lead iodide solution, and the sulfonate in the potassium perfluorobutyl sulfonate is used to coordinate with lead iodide to adjust the nucleation rate of the lead iodide film, so as to change the morphology of the lead iodide film, obtain the secondary nucleation of the larger lead iodide cluster and the lead iodide film with stronger crystallinity, promote the organic salt to interact with the lead iodide earlier and more fully in the subsequent organic salt spin coating process, help to form the perovskite film with larger crystal grains and better orientation, thereby reducing the content of residual lead iodide in the film, reducing the surface and internal defects, and effectively inhibiting the non-radiative recombination of excitons. In addition, due to the water resistance of fluorine in the potassium perfluorobutyl sulfonate and the fewer grain boundaries in the perovskite film, the perovskite film with the additive (potassium perfluorobutyl sulfonate) can effectively resist the corrosion of water vapor, so that the battery efficiency and stability are improved. The perovskite layer prepared by the present application has fewer recombination centers, and the prepared solar cell has higher efficiency and better stability. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 X-ray diffraction patterns of lead iodide films of Example 1 and Comparative Example 1 of the present application;

[0030] Figure 2A scanning electron microscope image of the lead iodide film of Example 1 of the present application;

[0031] Figure 3 A scanning electron microscope image of the lead iodide film of Comparative Example 1 of the present application;

[0032] Figure 4 A water contact angle image of the lead iodide film of Example 1 of the present application;

[0033] Figure 5 A water contact angle image of the lead iodide film of Comparative Example 1 of the present application;

[0034] Figure 6 A scanning electron microscope image of the perovskite film of Example 1 of the present application;

[0035] Figure 7 A scanning electron microscope image of the perovskite film of Comparative Example 1 of the present application;

[0036] Figure 8 A scanning electron microscope image of the perovskite film of Example 4 of the present application;

[0037] Figure 9 A battery photo of Example 1 of the present application after being placed under normal temperature and humidity conditions for 400 h;

[0038] Figure 10 A battery photo of Comparative Example 1 of the present application after being placed under normal temperature and humidity conditions for 400 h. DETAILED DESCRIPTION

[0039] The following examples are further illustrations of the present application and are not intended to limit the present application in any way. Any changes or modifications that one can make to the present application based on the spirit of the present application should be within the scope of the present application.

[0040] Example 1

[0041] A preparation method of a high-stability solar cell based on perovskite layer doping, comprising the following steps:

[0042] 1) Cleaning of the substrate

[0043] In the present embodiment, the substrate is indium tin oxide glass. The substrate is first cut to a suitable size, and then sequentially cleaned with deionized water, acetone and ethanol in an ultrasonic cleaning instrument for 15 minutes each, and then dried with nitrogen;

[0044] 2) Preparation of the electron transport layer

[0045] A tin dioxide precursor solution is coated on an indium tin oxide glass by a spin coating method, high-temperature annealing treatment and cooling to room temperature, and a dense tin dioxide film is formed on the surface of the indium tin oxide glass;

[0046] The tin dioxide precursor solution is prepared by mixing SnO2 colloidal solution and deionized water at a mass ratio of 1:5, the spin coating time of the tin dioxide precursor solution is 45 s, the annealing time is 30 min, and the annealing temperature is 150°C.

[0047] 3) Preparation of perovskite layer

[0048] 599.3 mg of PbI2 is added to 1 mL of a DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) mixed solution, and potassium perfluorobutyl sulfonate is added to obtain a PbI2 mixed solution with a concentration of 1 mg / mL, wherein the volume ratio of DMF to DMSO is 950:50;

[0049] The PbI2 mixed solution is spin coated on the tin dioxide film for 30 s, annealed for 30 s at 70°C, and a lead iodide film with a pore size of about 100 nm is formed;

[0050] 60 mg of FAI (formamidinium iodide) and 14 mg of MACl (methylamine chloride) are further added to 1 mL of IPA (isopropyl alcohol) solution to obtain an FAI solution;

[0051] The FAI solution is spin coated on the lead iodide film for 30 s, annealed for 13 min at 145°C, and an FAI film is finally formed, and the lead iodide film and the FAI film form a perovskite layer;

[0052] 4) Preparation of hole transport layer

[0053] 520 mg of bis(trifluoromethane) sulfonamide lithium salt is added to 1 mL of acetonitrile to obtain a bis(trifluoromethane) sulfonamide lithium salt solution;

[0054] 72.3 mg of Spiro-OMeTAD is further added to a mixed solution composed of 1 mL of chlorobenzene, 17.5 μL of the bis(trifluoromethane) sulfonamide lithium salt solution, and 29 μL of 4-tert-butylpyridine to obtain a hole transport layer precursor solution;

[0055] The hole transport layer precursor solution (i.e., the Spiro-OMeTAD solution) is spin coated on the surface of the perovskite layer for 20 s and oxidized for 8 h;

[0056] 5) Preparation of electrode

[0057] A metal electrode is evaporated on the hole transport layer.

[0058] Example 2

[0059] On the basis of Example 1, in step 3), the concentration of potassium perfluorobutyl sulfonate is 0.5 mg / mL, and the remaining steps are the same as Example 1.

[0060] Example 3

[0061] On the basis of Example 1, in step 3), the concentration of potassium perfluorobutyl sulfonate is 1.5 mg / mL, and the remaining steps are the same as Example 1.

[0062] Example 4

[0063] On the basis of Example 1, in step 3), the concentration of potassium perfluorobutyl sulfonate is 2 mg / mL, and the remaining steps are the same as Example 1.

[0064] Comparative Example 1

[0065] In step 3), 599.3 mg of PbI2 is weighed and added to 1 mL of a mixture of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide), and no potassium perfluorobutyl sulfonate is added.

[0066] The remaining steps are the same as Example 1.

[0067] The lead iodide thin film obtained by adding potassium perfluorobutyl sulfonate in Example 1 and the lead iodide thin film obtained without adding potassium perfluorobutyl sulfonate in Comparative Example 1 are analyzed by X-ray diffraction and scanning electron microscopy, as shown in Figure 1 、 Figure 2 and Figure 3 . Figure 1 The X-ray diffraction pattern shows that after adding potassium perfluorobutyl sulfonate, the diffraction peak intensity of the (001) crystal plane of the lead iodide thin film is significantly enhanced, and the half-peak width is reduced, indicating that the thin film has higher crystallinity. In the process of preparing perovskite thin film by two-step deposition method, before the reaction of organic ammonium salt, high crystallinity lead iodide can effectively shorten the formation time of subsequent perovskite phase.

[0068] Figure 2 、 Figure 3 The scanning electron microscope image shows that the addition of potassium perfluorobutyl sulfonate can make the lead iodide thin film form larger cluster structure and porous morphology (pore diameter about 100 nm), which not only facilitates the penetration of ammonium salt, but also provides guarantee for the secondary growth of lead iodide clusters, thereby promoting the preferential growth of perovskite crystals in the (001) direction, while effectively inhibiting the undesirable (111) orientation.

[0069] Figure 4 The water contact angle of the lead iodide film of Example 1 is 50.802°, Figure 5The water contact angle (43.601°) of the lead iodide film of Comparative Example 1 can be seen that the lead iodide film added with potassium perfluorobutyl sulfonate (Example 1) has better hydrophobicity, which helps to reduce the sensitivity of the film to moisture, thereby improving the stability of the device.

[0070] Figure 6 to Figure 8 The scanning electron microscope images of the perovskite films of the examples and the comparative examples are shown in FIG. 6 (Example 1) and FIG. 7 (Comparative Example 1). When the addition concentration of potassium perfluorobutyl sulfonate is appropriate (0.5-1.5 mg / mL), the grain size of the perovskite film increases, the number of grain boundaries decreases, and the amount of lead iodide residue near the grain boundaries decreases. This shows that the additive (potassium perfluorobutyl sulfonate) can effectively suppress charge recombination and reduce defects by optimizing the microstructure of the film, thereby improving the efficiency and stability of the device. Figure 8 It is shown that there is an optimal range of the concentration of the additive: when the concentration exceeds the range, the amount of lead iodide in the film increases sharply, and the perovskite grains become significantly smaller, which means that the number of defects in the film increases and the stability decreases.

[0071] Figure 9 and Figure 10 The schematic diagrams of the batteries of Example 1 and Comparative Example 1 after being placed in a normal temperature and humidity air environment for 400 hours are shown in FIG. 8 and FIG. 9, respectively. Due to the water resistance of the fluorine element in potassium perfluorobutyl sulfonate and the fewer grain boundary structures in the perovskite film, the perovskite film containing the additive (potassium perfluorobutyl sulfonate) can effectively resist water vapor erosion: the perovskite light-absorbing layer decomposes less, and the silver electrode in the device still maintains a metallic luster; while the battery without the additive, the perovskite light-absorbing layer has been completely decomposed, and the silver electrode has been almost completely blackened due to the reaction between the silver electrode and the iodine generated by the decomposition of the perovskite to form a large amount of silver iodide. The above results show that the device containing potassium perfluorobutyl sulfonate has better stability.

[0072] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement 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 preparing a high stability solar cell based on doping of a perovskite layer, characterized in that, The method comprises the following steps: 1) substrate cleaning: using indium tin oxide glass as a substrate, cleaning the substrate; 2) preparing an electron transport layer: coating a tin dioxide precursor solution on the substrate by a spin coating method, high-temperature annealing treatment and cooling to room temperature, and forming a dense tin dioxide film on the surface of the indium tin oxide glass; 3) preparing a perovskite layer: adding PbI2 into a mixed solution of DMF and DMSO, and then adding potassium perfluorobutyl sulfonate to obtain a PbI2 mixed solution; adding FAI and MACl into an IPA solution to obtain an FAI solution; depositing the PbI2 mixed solution and the FAI solution on the dense tin dioxide film by a two-step sequential deposition method to form a perovskite layer; 4) preparing a hole transport layer: preparing a hole transport layer precursor solution, spin coating the hole transport layer precursor solution on the perovskite layer, and performing oxidation; 5) preparing an electrode: evaporating a metal electrode on the hole transport layer.

2. The method for preparing a high stability solar cell based on a perovskite layer doping according to claim 1, characterized in that, In step 1), the substrate is cut into a proper size, and then sequentially cleaned with deionized water, acetone and ethanol in an ultrasonic cleaning instrument for 15 minutes, and then dried with nitrogen.

3. The method of claim 1, wherein the method is characterized by: In step 2), the preparation steps of the tin dioxide precursor solution are as follows: SnO2 colloidal solution and deionized water are mixed at a mass ratio of 1:

5.

4. The method for preparing a high-stability solar cell based on a perovskite layer doping according to claim 3, characterized in that, The spin coating time of the tin dioxide precursor solution is 45 s, the annealing time is 30 min, and the annealing temperature is 150 DEG C.

5. The method for preparing a high-stability solar cell based on a perovskite layer doping according to claim 1, characterized in that, In step 3), the preparation steps of the PbI2 mixed solution are as follows: 550-650 mg of PbI2 is added into 1 mL of a mixed solution of DMF and DMSO, and then potassium perfluorobutyl sulfonate is added to make the concentration of the potassium perfluorobutyl sulfonate 0.5-1.5 mg / mL.

6. The method for preparing a high stability solar cell based on a perovskite layer doping according to claim 5, characterized in that, In the mixed solution of DMF and DMSO, the volume ratio of DMF to DMSO is 950:

50.

7. The method of claim 1, wherein the method is characterized by: In step 3), the spin coating time of the PbI2 mixed solution is 20-40 s, the annealing time is 20-40 s, and the annealing temperature is 60-80 DEG C. 8.The method for preparing a high-stability solar cell based on a perovskite layer doping according to claim 1 or 5, characterized in that, In step 3), the preparation steps of the FAI solution are as follows: 50-70 mg of FAI and 10-15 mg of MACl are added into 1 mL of an IPA solution; In step 4), the preparation steps of the hole transport layer precursor solution are as follows: 500-550 mg of bis(trifluoromethane)sulfonamide lithium salt is added into 1 mL of acetonitrile to obtain a bis(trifluoromethane)sulfonamide lithium salt solution; 9. The method of claim 1, wherein the method is characterized by: 70-75 mg of Spiro-OMeTAD is added into a mixed solution composed of 1 mL of chlorobenzene, 17.5 microliters of the bis(trifluoromethane)sulfonamide lithium salt solution and 29 microliters of 4-tert-butylpyridine to obtain a hole transport layer precursor solution; The spin coating time of the hole transport layer precursor solution is 20 s, and the oxidation time is 8 h. The high-stability solar cell is prepared by the preparation method in any one of claims 1-9, and comprises:

10. A high stability solar cell based on perovskite layer doping, characterized by, a substrate; an electron transport layer located on the surface of the substrate; ​ A perovskite layer located on the surface of an electron transport layer, the perovskite layer comprising a lead iodide thin film and a formamidinium iodide thin film, the lead iodide thin film forming a certain number of microporous structures on the surface of its dense thin film by introducing potassium perfluorobutyl sulfonate, the pore size being 50-150 nanometers; A hole transport layer located on the surface of the perovskite layer; A metal electrode located on the surface of the hole transport layer.

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