A tin-lead mixed perovskite thin film, a preparation method and application thereof

Abstract

The application discloses a kind of tin lead mixed perovskite film and its preparation method and application, including the following steps: (1) the preparation of hole transport layer: (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous solution is spin-coated on indium tin oxide glass substrate, then annealing, and the indium tin oxide glass substrate / PEDOT:PSS is obtained;(2) the preparation of perovskite light-absorbing layer: tin lead mixed perovskite precursor solution is spin-coated on the PEDOT:PSS layer of indium tin oxide glass substrate / PEDOT:PSS, and anti-solvent chlorobenzene is added dropwise during spin-coating process, annealing treatment is carried out after spin-coating is completed, and then cysteine hydrochloride post-processing solution is spin-coated on perovskite film, and it is obtained.The doping and post-processing of cysteine hydrochloride (CysHCl) can improve the quality of Sn-Pb mixed perovskite film, reduce the defect state density of the film, increase the lifetime of charge carriers, and ultimately improve the photoelectric conversion efficiency of the battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar cells, and particularly relates to a tin-lead mixed perovskite film and a preparation method and application thereof. BACKGROUND

[0002] The photoelectric conversion efficiency of single-junction perovskite solar cells has been improved from 3.8% in 2009 to 25.7% at present, which is close to the highest conversion efficiency of crystalline silicon solar cells. However, the current high-efficiency single-junction perovskite solar cells are mainly based on pure lead-based perovskite absorber layers, but the band gap of the pure lead-based perovskite is 1.5-1.6 eV, which is not an ideal light-absorbing material. By adjusting the ratio of tin (Sn) to lead (Pb), the band gap of the tin-lead mixed perovskite can be reduced to about 1.2 eV. The bottom cell based on the tin (Sn)-lead (Pb) mixed perovskite light-absorbing material in combination with the wide-bandgap perovskite solar top cell can construct a full-perovskite tandem solar cell, so as to obtain a photoelectric conversion efficiency exceeding the Shockley-Queisser limit, and it is expected to be able to expand to flexible and lightweight photovoltaic applications.

[0003] As an important component of the full-perovskite tandem solar cell, the performance of the tin-lead mixed narrow-bandgap perovskite solar cell is crucial to the development of the full-perovskite tandem solar cell. At present, although the tin-lead mixed narrow-bandgap perovskite solar cell has obtained an authenticated efficiency of more than 23%, it is still lower than the efficiency of the pure lead-based perovskite solar cell, and the further development space thereof is mainly limited by the oxidation of Sn 2+ and the related defect chemical reaction, which causes a high defect state density in the perovskite film. Additives and interface engineering have been widely used to inhibit the oxidation of Sn 2+ and passivate the related defects, so as to reduce the non-radiative recombination of carriers in the perovskite film and improve the photoelectric conversion efficiency of the tin-lead mixed perovskite solar cell. On the other hand, a lower Sn 4+ concentration and defect state density also contribute to the improvement of the stability of the device. Therefore, a functional additive with multiple functional groups is particularly important for realizing a high-efficiency and stable tin-lead mixed narrow-bandgap perovskite solar cell. SUMMARY

[0004] In view of the above prior art, the application provides a tin-lead mixed perovskite film and a preparation method and application thereof, so as to solve the problems of the oxidation of Sn 2+ and the high defect state density in the existing tin-lead mixed perovskite film.

[0005] To achieve the above object, the technical scheme adopted by the application is to provide a preparation method of a tin-lead mixed perovskite film, comprising the following steps:

[0006] (1) Preparation of hole transport layer: (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous solution is coated on an indium tin oxide glass substrate, followed by annealing, to obtain an indium tin oxide glass substrate / PEDOT:PSS;

[0007] (2) Preparation of perovskite light absorption layer: tin-lead mixed perovskite precursor solution is coated on the PEDOT:PSS layer of the indium tin oxide glass substrate / PEDOT:PSS, and anti-solvent chlorobenzene is added dropwise during the coating process, followed by annealing treatment, and then cysteine hydrochloride post-processing solution is coated on the perovskite film, to obtain the perovskite solar cell.

[0008] On the basis of the above technical solutions, the application can also be improved as follows.

[0009] Further, the coating method of the (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous solution is spin coating, the spin coating speed is 3000-5000 rpm, the acceleration is 9000-11000 rpm / s, and the spin coating time is 50-70 s; in step (1), the annealing temperature is 140-180℃, and the annealing time is 15-30 min.

[0010] Further, the indium tin oxide glass is cleaned indium tin oxide glass, and the cleaning process comprises the following steps: first, rinsing the indium tin oxide glass with deionized water containing a glass cleaning agent, then ultrasonic treatment with deionized water and anhydrous ethanol for 15-30 min, followed by blowing dry with dry nitrogen, and finally placing in a UV-ozone cleaning machine for 15-20 min.

[0011] Further, the tin-lead mixed perovskite precursor solution is prepared by the following steps: in a nitrogen environment, 0.1-0.2 mol of FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 perovskite is added with SnF2 and NH4SCN in an amount of 5% and 2% of the sum of the molar amounts of Sn 2+ and Pb 2+ in the perovskite component, respectively, and then 1% of cysteine hydrochloride is added, which is less than the sum of the molar amounts of Sn 2+ and Pb 2+ , followed by dissolving in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide, and then stirring at 55-65℃ for 0.8-1.2 h, to obtain the tin-lead mixed perovskite precursor solution.

[0012] Further, the coating method of the tin-lead mixed perovskite precursor solution is spin coating, the spin coating speed is 3000-5000 rpm, and the spin coating time is 40-60 s; the dropwise adding time of the anti-solvent chlorobenzene is 15-25 s after the start of spin coating; the annealing temperature in step (2) is 90-110 ℃, and the annealing time is 8-12 min; the coating method of the cysteine hydrochloride post-processing solution is spin coating, the spin coating speed is 3000-5000 rpm, and the spin coating time is 20-40 s.

[0013] Further, the cysteine hydrochloride post-processing solution is prepared by the following steps: mixing the mixed solvent of isopropyl alcohol and toluene and the cysteine hydrochloride according to a liquid-material ratio of 5 mL:1-10 mg, and stirring at 55-65 ℃ for 1.5-2.5 h.

[0014] The application further provides the tin-lead mixed perovskite thin film prepared by the preparation method.

[0015] The application further provides the application of the tin-lead mixed perovskite thin film in the preparation of a solar cell.

[0016] Further, the method comprises the following steps: placing the tin-lead mixed perovskite thin film in a vacuum, and then sequentially depositing 18-22 nm of fullerene, 4-6 nm of bathocuproine and 90-110 nm of metal copper on the perovskite thin film.

[0017] Further, the deposition method is thermal evaporation.

[0018] The application has the beneficial effects that: the Sn-Pb mixed perovskite thin film is prepared by adding a multifunctional organic salt into a perovskite precursor solution and post-processing with the organic salt solution, and the multifunctional organic salt contains three groups of amino, carboxyl and hydrogen sulfide. The doping and post-processing of cysteine hydrochloride (CysHCl) can improve the quality of the Sn-Pb mixed perovskite thin film, reduce the defect state density of the thin film, increase the lifetime of the charge carriers, and ultimately improve the photoelectric conversion efficiency of the cell. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structure diagram of the additive and post-processing material CysHCl cation used in the application;

[0020] Figure 2 is a structure diagram of the Sn-Pb mixed perovskite solar cell prepared in the application;

[0021] Figure 3 is a scanning electron microscope (SEM) diagram of the untreated Sn-Pb mixed perovskite thin film prepared in the application;

[0022] Figure 4 is a SEM diagram of the CysHCl-doped Sn-Pb mixed perovskite thin film prepared in the application;

[0023] Figure 5 is a SEM image of the CysHCl simultaneously doped and post-treated Sn-Pb hybrid perovskite thin film prepared in the present application;

[0024] Figure 6 is an X-ray diffraction (XRD) image of the perovskite thin film prepared in the present application using three different treatment methods;

[0025] Figure 7 is a time-resolved photoluminescence spectrum (TRPL) image of the perovskite thin film prepared in the present application using three different treatment methods;

[0026] Figure 8 is a current density-voltage characteristic curve of the Sn-Pb hybrid perovskite solar cell prepared in the present application using three different treatment methods;

[0027] Figure 9 is a plot of the decay of the conversion efficiency of the untreated and CysHCl simultaneously doped and post-treated Sn-Pb hybrid perovskite solar cell prepared in the present application with storage time. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application will be described in detail below with reference to the accompanying examples.

[0029] Example 1

[0030] A method for preparing a tin-lead hybrid perovskite thin film, comprising the following steps:

[0031] (1) Preparation of a tin-lead hybrid perovskite precursor solution: In a nitrogen glove box, FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3perovskite were weighed according to the molar ratio, and SnF2(an additive, the molar amount of which is 5% of the sum of the molar amounts of Sn 2+ and Pb 2+ in the perovskite components) and NH4SCN(the molar amount of which is 2% of the sum of the molar amounts of Sn 2+ and Pb 2+ in the perovskite components) were added, followed by the addition of cysteine hydrochloride (CysHCl, the molar amount of which is 0.2% of the sum of the molar amounts of Sn 2+ and Pb 2+ in the perovskite components), which was then dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (the volume ratio of DMF to DMSO is 3:1), and stirred at 60°C for 1 h, to obtain a tin-lead hybrid perovskite precursor solution;

[0032] (2) Preparation of cysteine ​​hydrochloride (CysHCl) post-treatment solution: Dissolve 2 mg CysHCl in a mixed solvent of 2.5 mL isopropanol and 2.5 mL toluene, and stir at 60 °C for 2 h to obtain the solution.

[0033] (3) Cleaning of indium tin oxide (ITO) glass substrate: First, rinse the 2.5cm×2.5cm ITO glass with deionized water containing DECON90 cleaning agent, then treat it with deionized water and anhydrous ethanol for 25min each, then blow the cleaned ITO glass with dry nitrogen, and then put it into the UV-ozone cleaner for 18min.

[0034] (4) Preparation of hole transport layer: (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) aqueous solution was spin-coated onto the cleaned ITO glass at a rotation speed of 4000 rpm, an acceleration of 10000 rpm / s, and a spin-coating time of 60 s. After spin-coating, the glass substrate was annealed at 150℃ for 20 min to obtain ITO glass substrate / PEDOT:PSS.

[0035] (5) Preparation of perovskite light-absorbing layer: ITO glass substrate / PEDOT:PSS was transferred to a glove box, and 80 μL of Ln-Pb mixed perovskite precursor solution was spin-coated onto the PEDOT:PSS layer at a speed of 4000 rpm for 50 s. At the 20th s, the anti-solvent chlorobenzene (CB) was added. After spin-coating, ITO substrate / PEDOT:PSS / perovskite was transferred to a 100℃ hot stage for annealing for 10 min. CysHCl post-treatment solution was then spin-coated onto the perovskite film at a speed of 4000 rpm for 30 s.

[0036] Example 2

[0037] A method for preparing a tin-lead mixed perovskite thin film includes the following steps:

[0038] (1) Preparation of tin-lead mixed perovskite precursor solution: In a nitrogen glove box, weigh FA by molar ratio. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 perovskite, to which additive SnF2 (the molar amount of which is equal to the Sn content in the perovskite component) is added. 2+ and Pb 2+ 5% of the sum of molar amounts) and NH4SCN (whose molar amount is Sn in the perovskite component) 2+ and Pb 2+ 2% of the sum of molar amounts), then add cysteine ​​hydrochloride (CysHCl, whose molar amount is Sn in the perovskite component).2+ and Pb 2+ The solution was then dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (volume ratio of DMF to DMSO was 3:1) and stirred at 55°C for 1.2 h to obtain a solution of Sn-Pb mixed perovskite precursor.

[0039] (2) Preparation of Cysteine hydrochloride (CysHCl) post-treatment solution: 5 mg of CysHCl was dissolved in a mixed solvent of 2.5 mL of isopropanol and 2.5 mL of toluene, and then stirred at 55°C for 2.5 h to obtain a solution of CysHCl post-treatment solution.

[0040] (3) Cleaning of ITO glass substrate: A 2.5 cm x 2.5 cm ITO glass was first rinsed with deionized water containing DECON90 cleaning agent, and then ultrasonically treated with deionized water and anhydrous ethanol for 15 min each. The cleaned ITO glass was then blown dry with dry nitrogen and placed in an ultraviolet-ozone cleaning machine for 15 min.

[0041] (4) Preparation of hole transport layer: A (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) aqueous solution was spin-coated on the cleaned ITO glass at a speed of 3000 rpm and an acceleration of 11000 rpm / s for 50 s, and then annealed on a hot plate at 140°C for 30 min to obtain an ITO glass substrate / PEDOT:PSS.

[0042] (5) Preparation of perovskite light-absorbing layer: The ITO glass substrate / PEDOT:PSS was transferred to a glove box, and 80 μL of Sn-Pb mixed perovskite precursor solution was spin-coated on the PEDOT:PSS layer at a speed of 3000 rpm for 60 s, with dropwise addition of anti-solvent chlorobenzene (CB) at the 25th second. After spin-coating, the ITO substrate / PEDOT:PSS / perovskite was transferred to a hot plate at 90°C for annealing for 8 min, and then a CysHCl post-treatment solution was spin-coated on the perovskite film at a speed of 3000 rpm for 40 s.

[0043] Example 3

[0044] A method for preparing a tin-lead mixed perovskite film, comprising the following steps:

[0045] (1) Preparation of tin-lead mixed perovskite precursor solution: In a nitrogen glove box, FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3perovskite, and an additive SnF2 (with a molar amount of 0.5% of the sum of the molar amounts of the components of the perovskite) was added, and then dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (volume ratio of DMF to DMSO was 3:1) and stirred at 55°C for 1.2 h to obtain a solution of Sn-Pb mixed perovskite precursor.2+ and Pb 2+ 5% of the sum of the molar amounts) and NH4SCN (whose molar amount is 5% of the sum of the molar amounts of Sn 2+ and Pb 2+ 2% of the sum of the molar amounts), and then cysteine hydrochloride (CysHCl, whose molar amount is 5% of the sum of the molar amounts of Sn 2+ and Pb 2+ 1% of the sum of the molar amounts), and then dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (volume ratio of DMF to DMSO is 3:1), and stirred at 65°C for 0.8h to obtain;

[0046] (2) Preparation of a post-treatment solution of cysteine hydrochloride (CysHCl): 10mg of CysHCl was dissolved in a mixed solvent of 2.5mL of isopropanol and 2.5mL of toluene, and then stirred at 65°C for 1.5h to obtain;

[0047] (3) Cleaning of an indium tin oxide (ITO) glass substrate: a 2.5cm x 2.5cm ITO glass was first rinsed with deionized water containing DECON90 cleaning agent, and then ultrasonically treated with deionized water and anhydrous ethanol for 30min each, and then the cleaned ITO glass was blown dry with dry nitrogen, and then placed in an ultraviolet-ozone cleaning machine for 30min;

[0048] (4) Preparation of a hole transport layer: an aqueous solution of (3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) was spin-coated on the cleaned ITO glass, at a rotation speed of 5000rpm, an acceleration of 9000rpm / s, and a spin-coating time of 70s, and then annealed on a hot stage at 180°C for 15min to obtain an ITO glass substrate / PEDOT:PSS;

[0049] (5) Preparation of a perovskite light-absorbing layer: the ITO glass substrate / PEDOT:PSS was transferred into a glove box, and 80μL of Sn-Pb mixed perovskite precursor solution was spin-coated on the PEDOT:PSS layer, at a rotation speed of 5000rpm, a spin-coating time of 40s, and dropwise addition of anti-solvent chlorobenzene (CB) at the 15s mark, and then the ITO substrate / PEDOT:PSS / perovskite was transferred to a hot stage at 110°C for annealing for 12min, and then a post-treatment solution of CysHCl was spin-coated on the perovskite film, at a rotation speed of 5000rpm and a spin-coating time of 20s.

[0050] Comparative Example 1

[0051] The step (1) in Example 1 is cancelled, the step (2) is cancelled, and the CysHCI post-treatment solution spin-coating in step (3) is cancelled to obtain an untreated Sn-Pb mixed perovskite film.

[0052] Comparative Example 2

[0053] The step (2) in Example 1 is cancelled, and the CysHCI post-treatment solution spin-coating in step (3) is cancelled to obtain a CysHCI doped Sn-Pb mixed perovskite film.

[0054] Figures 3-5 is the SEM image of the three Sn-Pb mixed perovskite films obtained in Example 1, Comparative Example 1 and Comparative Example 2. There are other phases in the untreated perovskite film grain, which may be SnF2, and the SnF2 on the surface of the CysHCI treated perovskite film disappears. Figure 6 is the XRD image of the three perovskite films. As can be seen from the figure, the CysHCI doped and post-treated perovskite film shows higher intensity, which reflects that the CysHCI treated perovskite film has better crystallinity. In summary, the CysHCI treated perovskite film has better film quality.

[0055] The indium tin oxide (ITO) glass in Example 1, Comparative Example 1 and Comparative Example 2 is replaced with super white glass, and the remaining steps and parameters remain unchanged to obtain a CysHCI simultaneously doped and post-treated Sn-Pb mixed perovskite film, an untreated Sn-Pb mixed perovskite film, and a CysHCI doped Sn-Pb mixed perovskite film, respectively, and the three Sn-Pb mixed perovskite films are used for TRPL test. Figure 7 is the TRPL image of the above three Sn-Pb mixed perovskite films. As can be seen from the figure, the carrier lifetime in the CysHCI doped and post-treated perovskite film is more than 2 μs, which is much higher than the carrier lifetime (548 ns) in the untreated perovskite film. The carrier lifetime is closely related to the defects in the perovskite film, and the presence of defects will accelerate the recombination of electron-hole pairs. The improvement of carrier lifetime indicates that part of the defects in the perovskite film are passivated. In combination with the structure of CysHCI, it can be found that the S atom and the O atom in CysHCI have lone pair electrons, which can coordinate with the uncoordinated Sn atoms or Pb atoms at the grain boundary and surface of the perovskite film, thereby reducing the defect density of the perovskite film.

[0056] The three Sn-Pb mixed perovskite films obtained in Example 1, Comparative Example 1 and Comparative Example 2 were used to prepare solar cells, in particular, the ITO glass substrate / PEDOT:PSS / perovskite was transferred into a vacuum chamber, and 20 nm of fullerene (C60), 5 nm of bathocuproine (BCP) and 100 nm of Cu were sequentially deposited on the perovskite film by thermal evaporation, thereby completing the preparation of the Sn-Pb mixed perovskite solar cell. 60 Figure 8 is the current density-voltage characteristic curve of the Sn-Pb mixed perovskite solar cells obtained by the above three different treatments, the photoelectric conversion efficiency of the untreated device is 18%, and by CysHCl simultaneous doping and post-treatment, the open circuit voltage and fill factor of the device are greatly improved, and the device efficiency reaches 21.1%. At the same time, as shown in Figure 9 , the CysHCl treated Sn-Pb mixed perovskite solar cell shows better storage stability, after nearly 700 h of aging, the device can still maintain more than 96% of the initial efficiency, while the untreated device has fallen to less than 85% of the initial efficiency.

[0057] Although the specific embodiments of the present application are described in detail in combination with the embodiments, it should not be understood as limiting the protection scope of the patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the protection scope of the patent.​

Claims

1. A method for preparing a tin-lead mixed perovskite thin film, characterized by, It comprises the following steps: (1) Preparation of hole transport layer: (3, 4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous solution is coated on an indium tin oxide glass substrate, followed by annealing, to obtain an indium tin oxide glass substrate / PEDOT: PSS; (2) Preparation of perovskite light-absorbing layer: A tin-lead mixed perovskite precursor solution is coated onto the PEDOT:PSS layer of an indium tin oxide glass substrate / PEDOT:PSS, and chlorobenzene is added dropwise during the coating process. Then, annealing is performed, and a cysteine ​​hydrochloride post-treatment solution is coated onto the perovskite film to obtain the perovskite film. The tin-lead mixed perovskite precursor solution is prepared by the following steps: In a nitrogen atmosphere, FA is weighed in molar ratio. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 Sn from the perovskite components was added to I3 perovskite. 2+ and Pb 2+ 5% and 2% of the sum of their molar amounts of SnF2 and NH4SCN, respectively, plus a lower amount of Sn. 2+ and Pb 2+ A cysteine ​​hydrochloride solution with a total molar concentration of 1% was subsequently dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide, and then stirred at 55-65 °C for 0.8-1.2 h to obtain the post-treatment solution of cysteine ​​hydrochloride. The post-treatment solution of cysteine ​​hydrochloride was prepared by the following steps: a mixed solvent of isopropanol and toluene was mixed with cysteine ​​hydrochloride at a liquid-to-solid ratio of 5 mL: 1-10 mg, and then stirred at 55-65 °C for 1.5-2.5 h.

2. The method of claim 1, wherein: The coating method of the (3, 4-ethylenedioxythiophene)-polystyrene sulfonic acid aqueous solution is spin coating, the spin coating speed is 3000-5000 rpm, the acceleration is 9000-11000 rpm / s, and the spin coating time is 50-70 s; the annealing temperature in step (1) is 140-180 ℃, and the annealing time is 15-30 min.

3. The preparation method according to claim 1, characterized in that, The indium tin oxide glass is cleaned indium tin oxide glass, and the cleaning process comprises the following steps: first, rinsing the indium tin oxide glass with deionized water containing a glass cleaning agent, then ultrasonic treatment with deionized water and anhydrous ethanol for 15-30 min, followed by blowing dry with dry nitrogen, and finally placing in an ultraviolet-ozone cleaning machine for 15-20 min.

4. The method of claim 1, wherein: The coating method of the tin-lead mixed perovskite precursor solution is spin coating, the spin coating speed is 3000-5000 rpm, and the spin coating time is 40-60 s; the dropwise addition time of the anti-solvent chlorobenzene is 15-25 s after the start of spin coating; the annealing temperature in step (2) is 90-110 ℃, and the annealing time is 8-12 min; the coating method of the cysteine hydrochloride post-treatment solution is spin coating, the spin coating speed is 3000-5000 rpm, and the spin coating time is 20-40 s.

5. The tin-lead mixed perovskite thin film prepared by the preparation method according to any one of claims 1-4.

6. The application of the tin-lead mixed perovskite thin film according to claim 5 in the preparation of a solar cell.

7. Use according to claim 6, characterized in that, It comprises the following steps: placing the tin-lead mixed perovskite thin film in a vacuum, and then sequentially depositing 18-22 nm fullerene, 4-6 nm bathocuproine, and 90-110 nm metal copper on the perovskite thin film.

8. Use according to claim 7, characterized in that: The deposition method is thermal evaporation.

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