A method of solid-solid imprint annealing to improve polycrystalline perovskite crystal quality

Abstract

The application belongs to the technical field of photovoltaics, and discloses a method for improving the crystal quality of polycrystalline perovskite by solid-solid imprinting annealing, which adopts a pyridine molecular solid-state imprinting layer to perform solid-solid imprinting annealing treatment on perovskite, so that the perovskite orderly grows under certain pressure and temperature conditions. The technology can effectively avoid the structural degradation of the perovskite wet film caused by surface defects in the traditional annealing process, and at the same time, passivate various defects in the perovskite film, improve the interface energy level structure, and enhance the carrier transport capacity, thereby improving the efficiency and stability of the device. The solid-solid imprinting annealing process in the application is simple, the solid-state passivation layer can be repeatedly used for multiple times, and is suitable for large-area and different component systems of perovskite solar cells, and has high universality and commercial application prospect.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically to a method for improving the quality of polycrystalline perovskite crystals through solid-solid imprinting annealing. Background Technology

[0002] Solar energy, as a clean and renewable energy source, has received widespread attention from countries around the world. In recent decades, novel perovskite photovoltaic (PSC) technologies have made significant progress. Compared to traditional crystalline silicon solar cells, PSCs offer superior photoelectric conversion efficiency, more economical manufacturing costs, lower energy consumption in fabrication processes, and flexible and diverse applications, making them considered one of the most commercially promising next-generation photovoltaic technologies.

[0003] Polycrystalline perovskite films prepared by solution methods suffer from numerous defects (such as vacancies, interstitials, and rearrangements), particularly at the perovskite surface and grain boundaries. These defects lead to severe nonradiative carrier recombination, ion migration, and perovskite degradation, limiting device efficiency and stability. The formation of these defects is closely related to the perovskite annealing process. Traditional high-temperature thermal annealing promotes the diffusion and rearrangement of perovskite component ions or molecules, which is beneficial for nucleation and crystal growth. Appropriate annealing conditions can improve the integrity and regularity of perovskite crystals. However, studies have found that even when using perovskite precursors with stoichiometric ratios of organic ammonium salts and lead iodide, lead iodide (PbI2) still accumulates on the perovskite surface or at grain boundaries after annealing. This is because surface micro-degradation occurs during high-temperature annealing—the collapse of the perovskite crystal structure due to surface defects generated by heating. Furthermore, thermal annealing also introduces many crystal defects into the perovskite, among which iodine vacancy defects are extremely common. Researchers commonly use various passivating agents such as Lewis acids and bases, halide salts, ionic liquids, and small organic molecules to passivate defects in perovskite films. These passivation methods can achieve a certain degree of defect repair, but they directly ignore the degradation behavior of perovskite during annealing and cannot fundamentally solve the problem.

[0004] Furthermore, traditional passivation methods involve integrally coating the passivating agent onto a polycrystalline perovskite thin film to construct a two-dimensional / three-dimensional perovskite heterojunction structure. This results in most of the perovskite surface, which does not require passivation, being covered with passivating material. These insulating two-dimensional layered structures hinder carrier transport, thus limiting the photovoltaic performance of perovskite solar cells. Therefore, seeking more efficient, controllable, and universally applicable perovskite annealing processes is crucial for promoting the development of high-quality perovskite solar cells. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a simple, efficient, and universal solid-solid imprinting annealing method that suppresses structural degradation of polycrystalline perovskite films due to surface defects during traditional thermal annealing, improves the crystallinity and film quality of perovskite, and further enhances the photoelectric conversion efficiency and long-term stability of perovskite solar cells.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for improving the quality of polycrystalline perovskite crystals by solid-solid imprinting annealing involves first preparing a pyridine molecular solid imprint layer, then covering the surface of the perovskite wet film with the solid imprint layer during the initial stage of perovskite annealing, and annealing under certain pressure and temperature conditions until the annealing process is completed.

[0008] As one possible implementation, further, the N in the pyridine molecule is related to (CH2). x NH2 is in the ortho position, and it can be any one of 2-aminopyridine, 2-aminomethylpyridine, 2-(2-aminoethyl)pyridine, etc.

[0009] As one possible implementation, the initial annealing period is 1 to 5 minutes after the start of annealing, the annealing temperature is 120 to 150°C, the total annealing time is 10 to 30 minutes, and the pressure is 0.049 to 0.1225 MPa.

[0010] As one possible implementation, the method for improving the quality of polycrystalline perovskite crystals through solid-solid imprint annealing specifically includes the following steps:

[0011] 1) Processing conductive glass: Cut the conductive glass to the required size and clean it for later use;

[0012] 2) Preparation of tin dioxide electron transport layer: Prepare raw material solution and prepare tin dioxide thin film on glass treated in step 1) by chemical bath deposition method;

[0013] 3) Preparation of pyridine solid imprint layer: Prepare pyridine isopropanol solution, coat the glass surface treated in step 1) with pyridine molecular layer, and then perform annealing treatment;

[0014] 4) Preheating of the imprinted weights: Place the weights on the heating plate for preheating;

[0015] 5) Preparation of perovskite thin film: Prepare a perovskite precursor solution and drop it onto the substrate treated in step 2) to prepare a wet film;

[0016] 6) Solid-solid imprinting annealing: Under heating conditions, the pyridine solid imprinting layer prepared in step 3) is covered on the surface of the perovskite film, and the preheated weight in step 4) is pressed on the covering layer. Solid-solid imprinting is performed in the early stage of perovskite annealing until the perovskite annealing is completed, and the imprinting layer is removed.

[0017] As one possible implementation, the method for improving the quality of polycrystalline perovskite crystals through solid-solid imprint annealing further includes:

[0018] 7) Preparation of Spiro-OMeTAD hole transport layer: Prepare Spiro-OMeTAD chlorobenzene solution, coat it on the perovskite film prepared in step 6), and then place the film in a constant temperature and humidity drying oven for oxidation treatment.

[0019] 8) Fabrication of metal counter electrode: A high work function metal counter electrode is deposited on the Spiro-OMeTAD thin film treated in step 7) using a vacuum thermal evaporation method.

[0020] As one possible implementation, further, the conductive glass substrate in step 1) is selected from any one of flexible substrates such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and polyester (PET / ITO, PEN / ITO), with a sheet resistance of 5–20 Ω / cm. 2 The cleaning steps for conductive glass include:

[0021] The glass was ultrasonically cleaned sequentially with glass cleaning fluid, deionized water, acetone, ethanol and isopropanol, and then dried before being treated with a UV-ozone cleaner. The ultrasonic cleaning time was 15-20 minutes, and the UV-ozone cleaner treatment time was 15-30 minutes at a temperature of 20-30°C.

[0022] As one possible implementation, further, the preparation method of the raw material solution in step 2) is as follows: dissolve 2g of urea, 2mL of hydrochloric acid, 40uL of trifluoroacetic acid and 0.44g of SnCl2·2H2O in 160mL of deionized water;

[0023] The chemical bath deposition method is as follows: the conductive glass substrate is immersed in the raw material solution, reacted at 90°C for 4 hours, the glass is taken out, ultrasonically cleaned with deionized water and isopropanol for 5 minutes respectively, rinsed with deionized water and ethanol, and then dried by nitrogen flow.

[0024] As one possible implementation, further, the pyridine concentration in the pyridine isopropanol solution in step 3) is 0.08–0.42 mol / L, with an optimal concentration of 0.25 mol / L; the preparation method is as follows: take an appropriate amount of pyridine molecules and dissolve them in 1 mL of isopropanol, then stir and mix thoroughly.

[0025] The pyridine isopropanol solution was applied to the glass surface treated in step 1) by spin coating or immersion.

[0026] The spin coating method is as follows: take 50 μL of pyridine isopropanol solution, drop it onto the glass surface and spin coat to form a film; the spin coating speed is 500-3000 rpm and the spin coating time is 30-50 s; the immersion method is as follows: immerse the glass in pyridine isopropanol solution for 1-5 min;

[0027] The annealing temperature is 80–120°C, and the annealing time is 5 min.

[0028] As one possible implementation, further, the weight in step 4) is a chrome-plated weight with good thermal conductivity; the weight mass is 2-5 kg, thereby controlling the imprinting force; the preheating temperature is 120-150℃, and the preheating time is 3-5 min;

[0029] In step 5), the perovskite precursor solution is dropped onto the substrate treated in step 2), and a film is formed by spin coating using a one-step anti-solvent method; wherein, the spin coating speed is 1000-5000 rpm, the spin coating time is 10-50 s, and the anti-solvent is diethyl ether or chlorobenzene;

[0030] The concentration of the perovskite precursor solution is 1.5–1.8 mol / L; the solvent system is a mixture of DMF and DMSO, with a DMF:DMSO volume ratio of 4:1 to 9:1.

[0031] The perovskite component is any one of formamidinium iodide perovskite (FAPbI3), methylammonium iodide perovskite (MAPbI3), cesium-based perovskite (CsPbI3), or a ternary blend perovskite.

[0032] As one possible implementation, further, the preparation method of the Spiro-OMeTAD chlorobenzene solution in step 7) is as follows: dissolve 73.2 mg Spiro-OMeTAD in 1 mL of chlorobenzene and stir for 1 h, then add 28.8 μL of 4-tert-butylpyridine and 17.6 μL of 520 mg·mL⁻¹. -1 The acetonitrile solution of LiTFSI was stirred for another 1 hour.

[0033] The spin coating speed is 3000 rpm, the spin coating time is 30 s; the drying oven temperature is 20-25℃, the humidity is 10-20%, and the oxidation time is 20 h.

[0034] The metal mentioned in step 8) is Au or Ag; the evaporation rate is 0.005 to 0.2 nm / s, the evaporation temperature is 900 to 1000℃, the evaporation time is 20 to 30 min, and the electrode thickness is 60 to 90 nm.

[0035] The beneficial effects of this invention are as follows:

[0036] Compared with traditional perovskite annealing methods, the solid-solid imprint annealing method provided by this invention has the following advantages:

[0037] 1) It slows down the evaporation of the solvent, reduces the migration rate of perovskite components, provides sufficient time for perovskite crystal growth, and promotes the formation of large grains. At the same time, it guides the solvent to migrate horizontally, allowing the perovskite wet film to grow epitaxially and orderly in a limited space, improving the regularity and order of the perovskite crystals, and improving the flatness of the perovskite film.

[0038] 2) Apply the same annealing temperature to both the upper and lower sides of the perovskite film to ensure that the crystal growth environment at the upper and lower interfaces of the perovskite is consistent, thereby promoting the synchronous growth of perovskite crystals at the upper and lower interfaces and improving the overall quality of the perovskite film.

[0039] 3) Pyridine molecules are introduced as a solid-state imprint layer to avoid the damage to the perovskite surface caused by organic solvents in traditional pyridine passivation methods. At the same time, it precisely coordinates iodine vacancy defects, iodine interstitial defects, and uncoordinated lead ion defects generated at the polycrystalline perovskite interface, avoiding excess pyridine molecules covering the perovskite surface and achieving high-efficiency and high-selectivity passivation.

[0040] 4) Applicable to perovskite films and systems of varying areas, the immersion preparation method for solid-state imprinting layers can be matched to perovskite films of different areas, showing promising prospects for large-scale applications. Furthermore, this solid-state imprinting layer can be reused repeatedly, undergoing multiple solid-to-solid imprinting annealing treatments on perovskite films with no difference in effect, which helps reduce the cost of passivation materials and enhances commercial application value. Attached Figure Description

[0041] Figure 1 A schematic diagram of the preparation of pyridine solid imprinted layer and solid-solid imprinting annealing process;

[0042] Figure 2 Scanning electron microscope images of perovskite thin films prepared by conventional annealing (without pyridine molecules), conventional annealing (2-(2-aminoethyl)pyridine), and solid-solid imprint annealing (2-(2-aminoethyl)pyridine);

[0043] Figure 3 In-situ grazing-incidence wide-angle X-ray scattering patterns on the surface of perovskite thin films prepared by conventional annealing and solid-solid imprinting annealing;

[0044] Figure 4 Photoluminescence mapping patterns of perovskite thin films prepared by conventional annealing and solid-solid imprinting annealing;

[0045] Figure 5Current density-voltage forward and reverse scan curves for perovskite solar cells (effective area 0.1 cm2) prepared by conventional annealing and solid-solid imprinting annealing;

[0046] Figure 6 Stability testing of devices prepared by conventional annealing and solid-solid imprint annealing at maximum power point (MPP tracking);

[0047] Figure 7 Scanning electron microscope images of perovskite thin films prepared by spin coating and immersion methods, followed by solid-solid imprinting.

[0048] Figure 8 Large-area (effective area 1cm²) prepared by solid-solid imprinting annealing 2 Current density-voltage forward and reverse scan curves of perovskite solar cells;

[0049] Figure 9 A statistical chart showing the efficiency of devices fabricated using the same solid-state imprinting layer to imprint 30 perovskite films.

[0050] Figure 10 Scanning electron microscope images of the surfaces of perovskite thin films with different compositions prepared by solid-solid imprinting. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] See attached document Figure 1 As shown, this invention provides a method for improving the quality of polycrystalline perovskite crystals through solid-solid imprint annealing, the specific steps of which are as follows:

[0053] 1) Treatment of conductive glass: Cut the conductive glass into standard sizes, and ultrasonically clean it sequentially with glass cleaning solution, deionized water, acetone, ethanol, and isopropanol. After drying, treat it with a UV-ozone cleaner for 15-30 minutes at a temperature of 20-30℃, and collect it for later use. The conductive glass substrate is one of the following flexible substrates: indium tin oxide (ITO), fluorine-doped tin oxide (FTO), polyester (PET / ITO, PEN / ITO), etc., with a sheet resistance of 5-20 Ω / cm. 2 .

[0054] 2) Preparation of tin dioxide electron transport layer: Dissolve 2g urea, 2mL hydrochloric acid, 40uL trifluoroacetic acid and 0.44g SnCl2·2H2O in 160mL deionized water to obtain raw material solution; prepare tin dioxide film on the glass treated in step 1) by chemical bath deposition method; wherein, the chemical bath deposition method is as follows: immerse the glass substrate in the raw material solution, react at 90℃ for 4h, take out the glass, ultrasonically clean it with deionized water and isopropanol for 5min respectively, rinse it with deionized water and ethanol, and then dry it with nitrogen gas flow.

[0055] 3) Preparation of pyridine solid-state imprinted layer: Dissolve an appropriate amount of pyridine molecules in 1 mL of isopropanol, stir and mix evenly to obtain a pyridine isopropanol solution with a pyridine concentration of 0.08–0.42 mol / L; coat the glass surface treated in step 1) with a pyridine molecular layer, and then anneal it at a temperature of 80–120℃ for 5 min. The coating methods include spin coating and immersion coating, which can meet the needs of small-area laboratory applications and large-scale applications. Spin coating involves adding 50 μL of pyridine isopropanol solution to the glass surface for spin coating; the spin coating speed is 500–3000 rpm, and the spin coating time is 30–50 s. Immersion coating involves immersing the glass in the pyridine isopropanol solution for 1–5 min.

[0056] 4) Preheating of the imprinting weight: Place the freshly chrome-plated weight (weight mass is 2-5 kg, and the imprinting force is adjusted accordingly) on the hot plate for preheating. The preheating temperature is 120-150℃ and the preheating time is 3-5 min.

[0057] 5) Preparation of perovskite thin films: Prepare a 1.5–1.8 mol / L perovskite precursor solution, wherein the solvent system of the perovskite precursor solution is a mixed solvent of DMF and DMSO, with a DMF:DMSO volume ratio of 4:1–9:1. The perovskite component is any one of formamidinium iodide perovskite (FAPbI3), methylammonium iodide perovskite (MAPbI3), cesium-based perovskite (CsPbI3), or a ternary blend perovskite.

[0058] Next, the above solution is dropped onto the substrate treated in step 2) in a glove box, and a film is formed by spin coating using a one-step anti-solvent method. The spin coating speed is 1000-5000 rpm and the spin coating time is 10-50 s. The anti-solvent is diethyl ether or chlorobenzene.

[0059] 6) Solid-to-solid imprint annealing: Transfer the wet perovskite film from step 5) to the hot stage, cover the perovskite surface with the pyridine solid imprint layer prepared in step 3), and then press the preheated weights from step 4) onto the covering layer (pressure of 0.049–0.1225 MPa). Perform solid-to-solid imprinting in the early stage of perovskite annealing (1–5 min from the start of annealing) until the end of perovskite annealing, and then remove the imprint layer; the annealing temperature during this period is 120–150 °C; the total annealing time is 10–30 min.

[0060] 7) Preparation of Spiro-OMeTAD hole transport layer: Dissolve 73.2 mg Spiro-OMeTAD in 1 mL of chlorobenzene and stir in a glove box for 1 h; then add 28.8 μL of 4-tert-butylpyridine and 17.6 μL of acetonitrile solution of LiTFSI (520 mg·mL⁻¹). -1 Continue stirring for 1 hour to prepare Spiro-OMeTAD chlorobenzene solution, thus obtaining Spiro-OMeTAD chlorobenzene solution;

[0061] Spiro-OMeTAD chlorobenzene solution was spin-coated onto the perovskite film prepared in step 6) at a spin speed of 3000 rpm for 30 s. The film was then placed in a constant temperature and humidity drying oven at 20–25 °C and 10–20% for 20 h for oxidation treatment.

[0062] 8) Preparation of metal counter electrode: A metal (Au or Ag) counter electrode with high work function is deposited on the Spiro-OMeTAD thin film treated in step 7) by vacuum thermal evaporation; wherein the evaporation rate is 0.005-0.2 nm / s, the evaporation temperature is 900-1000℃, the evaporation time is 20-30 min, and the electrode thickness is 60-90 nm.

[0063] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0064] Example 1:

[0065] In this embodiment, a 2-(2-aminoethyl)pyridine solid-state imprinted layer was prepared by spin coating, followed by a solid-on-solid imprinting method to prepare a perovskite thin film, and then a perovskite solar cell (effective area 0.1 cm²) was assembled. 2 The specific steps are as follows:

[0066] (1) Processing the ITO conductive glass substrate: In this embodiment, a sheet resistance of 12Ω / cm is used. 2 The substrate is ITO. First, the ITO is cut into 2x2cm pieces. 2The glass was laser-etched to standard dimensions. Then, it was sequentially ultrasonicated for 15 minutes each with glass cleaning fluid, deionized water, acetone, ethanol, and isopropanol, followed by drying with compressed air. Finally, it was cleaned for 20 minutes at room temperature using a UV-ozone cleaner.

[0067] (2) Preparation of tin dioxide electron transport layer: Dissolve 2g urea, 2mL hydrochloric acid, 40uL trifluoroacetic acid and 0.44g SnCl2·2H2O in 160mL deionized water and stir until homogeneous. Immerse the ITO obtained in step (1) in the above raw material solution and react at 90℃ for 4h. Remove the ITO, ultrasonically clean it with deionized water and isopropanol for 5min each, rinse it with distilled water and ethanol, and then dry it with a nitrogen stream.

[0068] (3) The method for preparing the 2-(2-aminoethyl)pyridine solid imprint layer is as follows: Prepare 1 mL of 0.25 mol / L 2-(2-aminoethyl)pyridine isopropanol solution, take 50 μL of the above solution, drop it onto the ITO substrate obtained in step (1), and spin-coat it to form a film. The spin-coating speed is 1000 rpm and the spin-coating time is 30 s. Then anneal at 100℃ for 5 min. At this time, place a 2 kg chromium-plated weight on a hot plate at 150℃ for preheating for 3 min.

[0069] (4) Preparation of FAPbI3 perovskite light-absorbing layer: Weigh 265 mg FAI, 710 mg PbI2 and 15 mg MACl and dissolve them in 1 mL of DMF / DMSO (v:v = 8:1) mixed solvent, stir overnight, and then filter the above solution with a PTFE filter head (0.45 μm). Prepare perovskite film in a glove box, take 50 μL of the above solution and drop it onto the glass substrate obtained in step (2), and spin-coat the film. Specifically, spin-coat is first performed at a spin speed of 1000 rpm and a spin time of 10 s, and then at a spin speed of 5000 rpm and a spin time of 30 s in one step. In the last 15 s of the spin-coating process, 700 μL of diethyl ether is rapidly dropped onto the perovskite film. After spin-coating, the glass is transferred to a hot stage at 150 °C for annealing.

[0070] (5) Solid-solid imprinting annealing process: At the 3-minute mark of the perovskite film annealing, the solid imprinting layer obtained in step (3) is covered onto the perovskite surface obtained in step (4), and the preheated weight in step (3) is pressed onto the covering layer. The imprinting annealing is continued with a pressure of 0.049 MPa, an annealing temperature of 150°C, and a total annealing time of 15 minutes. After the annealing is completed, the weight is removed and the film is allowed to cool naturally to room temperature.

[0071] (6) Preparation of the Spiro-OMeTAD hole transport layer: Weigh 73.2 mg of Spiro-OMeTAD in a glove box, dissolve it in 1 mL of chlorobenzene, and stir at room temperature for 1 h. Then add 28.8 μL of 4-tert-butylpyridine and 17.6 μL of acetonitrile solution of LiTFSI (520 mg / mL). -1 Continue stirring for 1 hour. Take 30 μL of Spiro-OMeTAD chlorobenzene solution and drop it onto the perovskite film obtained in step (5), spin-coating it at a speed of 3000 rpm for 30 seconds. Then transfer the glass to a constant temperature and humidity chamber at 25°C and 15% for oxidization for 20 hours.

[0072] (7) Preparation of Au counter electrode: 100 mg of Au was placed in a vacuum thermal evaporation apparatus to prepare the counter electrode on the thin film obtained in step (6). The evaporation rate was 0.05 nm / s, the evaporation temperature was 900-1000 °C, the evaporation time was 20-30 min, and the thickness of the counter electrode was 80 nm.

[0073] Example 2:

[0074] In this embodiment, a 2-(2-aminoethyl)pyridine solid imprint layer is prepared by immersion method, and then a perovskite thin film is prepared by solid-solid imprinting method, and then a perovskite solar cell is assembled.

[0075] The preparation method of this embodiment is basically the same as that of Example 1, except for step (3). In this embodiment, step (3) prepares the 2-(2-aminoethyl)pyridine solid imprint layer: prepare 10 mL of 0.25 mol / L 2-(2-aminoethyl)pyridine isopropanol solution, pour the above solution into a petri dish, then place the ITO substrate obtained in step (1) into the petri dish and soak for 3 min, then remove it and anneal at 100℃ for 5 min. At this time, place a 2 kg chromium-plated weight on a hot plate at 150℃ for preheating for 3 min. Other specific steps are the same as in Example 1.

[0076] Example 3:

[0077] In this embodiment, a 2-(2-aminoethyl)pyridine solid-state imprinting layer was prepared by immersion method, and then a perovskite thin film was prepared by solid-solid imprinting method, followed by assembly of a large area (effective area 1 cm²). 2 Perovskite solar cells.

[0078] The ITO glass used in step (1) of this embodiment has a size of 2x2cm. 2 It can also be enlarged to 5x5cm 2 10x10cm 2 A glass substrate of the same size. The effective area of ​​the sub-cell prepared in step (7) is 1 cm². 2This can also be scaled up to a larger effective area battery. Other specific steps are the same as in Example 2.

[0079] Example 4:

[0080] In this embodiment, a 2-(2-aminoethyl)pyridine solid imprinted layer is prepared by spin coating, and then the same solid imprinted layer is subjected to multiple solid-to-solid imprinting annealing processes to assemble a perovskite solar cell.

[0081] In this embodiment, step (4) is repeated to prepare multiple (up to 30) FAPbI3 perovskite light-absorbing layers. When annealing each perovskite, the same 2-(2-aminoethyl)pyridine solid imprinting layer prepared in step (3) is used for solid-solid imprinting annealing. Other specific steps are the same as in Example 1.

[0082] Example 5:

[0083] In this embodiment, a 2-(2-aminoethyl)pyridine solid imprint layer is prepared by spin coating, and then a MAPbI3 perovskite thin film is prepared by solid-solid imprinting, and then a perovskite solar cell is assembled.

[0084] In this embodiment, the method for preparing the MAPbI3 perovskite light-absorbing layer in step (4) is as follows: a MAPbI3 precursor solution with a PbI2 and MA1 molar ratio of 1:1 is prepared and dissolved in 1 mL of a DMF / DMSO (v:v = 7:3) mixed solvent, resulting in a solution concentration of 1.2 mol / L. The solution is stirred overnight and then filtered through a PTFE filter (0.45 μm). A perovskite film is prepared in a glove box. 50 μL of the above solution is dropped onto the glass substrate obtained in step (2) and spin-coated. Specifically, a rotation speed of 4000 rpm and a rotation time of 60 s are used, and 260 μL of chlorobenzene antisolvent is rapidly dropped onto the perovskite film at the 25th second. After spin-coating, the glass is transferred to a hot plate at 120°C for annealing. Other specific steps are the same as in Example 1.

[0085] Example 6:

[0086] In this embodiment, a 2-(2-aminoethyl)pyridine solid imprint layer was prepared by spin coating, and then Cs was prepared by solid-solid imprinting. x FA 1-x PbI3 perovskite thin films were then used to assemble perovskite solar cells.

[0087] In this embodiment, step (4) prepares Cs x FA 1-x The method for preparing the PbI3 perovskite light-absorbing layer is as follows: A CsI layer is prepared with a molar ratio of FAI, CsI, and PbI2 of 1.3:0.065:1.365. x FA 1-xA PbI3 precursor solution was dissolved in 1 mL of a DMF / DMSO (v:v = 4:1) mixed solvent, resulting in a solution concentration of 1.4 mol / L. The solution was stirred overnight and then filtered through a PTFE filter (0.45 μm). A perovskite film was prepared in a glove box. 50 μL of the solution was dropped onto the glass substrate obtained in step (2) and spin-coated. Specifically, a one-step spin-coating process was performed first at a spin speed of 1000 rpm for 10 s, and then at a spin speed of 5000 rpm for 30 s. In the last 15 s of the spin-coating process, 260 μL of chlorobenzene antisolvent was rapidly dropped onto the perovskite film. After spin-coating, the glass was transferred to a hot plate at 150 °C for annealing. Other specific steps were the same as in Example 1.

[0088] Example 7:

[0089] In this embodiment, a 2-(2-aminoethyl)pyridine solid imprint layer was prepared by spin coating, and then MA was prepared by solid-solid imprinting. x FA 1-x Pb(I y Br 1-y )3 Perovskite thin film, and then assembled into perovskite solar cells.

[0090] In this embodiment, step (4) prepares MA x FA 1-x Pb(I y Br 1-y The method for preparing the perovskite light-absorbing layer is as follows: A MA solution with a molar ratio of FAPbI3 to MAPbBr3 of 0.95:0.05 is prepared. x FA 1-x Pb(I y Br 1-y The precursor solution was dissolved in 1 mL of a DMF / DMSO (v:v = 8:1) mixed solvent, resulting in a solution concentration of 1.4 mol / L. The solution was stirred overnight and then filtered through a PTFE filter (0.45 μm). A perovskite film was prepared in a glove box. 50 μL of the solution was dropped onto the glass substrate obtained in step (2) and spin-coated. Specifically, a one-step spin-coating process was performed first at a spin speed of 1000 rpm for 10 s, and then at a spin speed of 5000 rpm for 30 s. In the last 15 s of the spin-coating process, 700 μL of diethyl ether antisolvent was rapidly dropped onto the perovskite film. After spin-coating, the glass was transferred to a hot plate at 150 °C for annealing. Other specific steps were the same as in Example 1.

[0091] Comparative Example 1:

[0092] This embodiment uses a conventional annealing method to prepare a perovskite thin film, and then assembles a perovskite solar cell. The specific steps are as follows:

[0093] (1) Processing the ITO conductive glass substrate: In this embodiment, a sheet resistance of 12Ω / cm is used. 2 The ITO is a conductive glass substrate. First, the ITO is cut into 2x2cm pieces. 2 The glass was laser-etched to standard dimensions. Then, it was sequentially ultrasonicated for 15 minutes each with glass cleaning fluid, deionized water, acetone, ethanol, and isopropanol, followed by drying with compressed air. Finally, it was cleaned for 20 minutes at room temperature using a UV-ozone cleaner.

[0094] (2) Preparation of tin dioxide electron transport layer: Dissolve 2g urea, 2mL hydrochloric acid, 40uL trifluoroacetic acid and 0.44g SnCl2·2H2O in 160mL deionized water and stir until homogeneous. Immerse the ITO obtained in step (1) in the above raw material solution and react at 90℃ for 4h. Remove the ITO, ultrasonically clean it with deionized water and isopropanol for 5min each, rinse it with distilled water and ethanol, and then dry it with a nitrogen stream.

[0095] (3) Preparation of FAPbI3 perovskite light-absorbing layer: Weigh 265 mg FAI, 710 mg PbI2 and 15 mg MACl and dissolve them in 1 mL of DMF / DMSO (v:v = 8:1) mixed solvent, stir overnight, and then filter the above solution with a PTFE filter head (0.45 μm). Prepare perovskite film in glove box, take 50 μL of the above solution and drop it onto the glass substrate obtained in step (2), and spin-coat the film. Specifically, spin-coat is first performed at a spin speed of 1000 rpm and a spin time of 10 s, and then at a spin speed of 5000 rpm and a spin time of 30 s in one step. In the last 15 s of the spin-coating process, 700 μL of diethyl ether antisolvent is quickly dropped onto the perovskite film. After spin-coating, the glass is transferred to a hot stage at 150 °C for annealing for 15 min and then naturally cooled to room temperature.

[0096] (4) Preparation of Spiro-OMeTAD hole transport layer: Weigh 73.2 mg of Spiro-OMeTAD in a glove box, dissolve it in 1 mL of chlorobenzene, and stir for 1 h. Then add 28.8 μL of 4-tert-butylpyridine and 17.6 μL of acetonitrile solution of LiTFSI (520 mg / mL). -1 Continue stirring for 1 hour. Take 30 μL of Spiro-OMeTAD chlorobenzene solution and add it dropwise to the perovskite film obtained in step (3) for spin coating. The spin coating speed is 3000 rpm and the spin coating time is 30 s. Then transfer the glass to a constant temperature and humidity chamber at 25℃ and 15% humidity for oxidization for 20 hours.

[0097] (5) Preparation of Au counter electrode: 100 mg Au was placed in a vacuum thermal evaporation apparatus and Au counter electrode was deposited on the thin film obtained in step (4) with the process parameters of evaporation rate of 0.05 nm / s, evaporation temperature of 900-1000℃ and evaporation time of 20-30 min. The thickness of Au counter electrode was 80 nm.

[0098] Comparative Example 2:

[0099] This embodiment uses a traditional annealing method to prepare a perovskite thin film, then spin-coates 2-(2-aminoethyl)pyridine molecules onto the perovskite surface for passivation, and finally assembles a perovskite solar cell. The specific steps are as follows:

[0100] (1) Processing the ITO conductive glass substrate: In this embodiment, a sheet resistance of 12Ω / cm is used. 2 The ITO is a conductive glass substrate. First, the ITO is cut into 2x2cm pieces. 2 The glass was laser-etched to standard dimensions. Then, it was sequentially ultrasonicated for 15 minutes each with glass cleaning fluid, deionized water, acetone, ethanol, and isopropanol, followed by drying with compressed air. Finally, it was cleaned for 20 minutes at room temperature using a UV-ozone cleaner.

[0101] (2) Preparation of tin dioxide electron transport layer: Dissolve 2g urea, 2mL hydrochloric acid, 40uL trifluoroacetic acid and 0.44g SnCl2·2H2O in 160mL deionized water and stir until homogeneous. Immerse the ITO obtained in step (1) in the above raw material solution and react at 90℃ for 4h. Remove the ITO, ultrasonically clean it with deionized water and isopropanol for 5min each, rinse it with distilled water and ethanol, and then dry it with a nitrogen stream.

[0102] (3) Preparation of FAPbI3 perovskite light-absorbing layer: Weigh 265 mg FAI, 710 mg PbI2 and 15 mg MACl and dissolve them in 1 mL of DMF / DMSO (v:v = 8:1) mixed solvent, stir overnight, and then filter the above solution with a PTFE filter head (0.45 μm). Prepare perovskite film in glove box, take 50 μL of the above solution and drop it onto the glass substrate obtained in step (2), and spin-coat the film. Specifically, spin-coat is first performed at a spin speed of 1000 rpm and a spin time of 10 s, and then at a spin speed of 5000 rpm and a spin time of 30 s in one step. In the last 15 s of the spin-coating process, 700 μL of diethyl ether antisolvent is quickly dropped onto the perovskite film. After spin-coating, the glass is transferred to a hot stage at 150 °C for annealing for 15 min and then naturally cooled to room temperature.

[0103] (4) Passivation of the perovskite surface: Weigh 3 mg of 2-(2-aminoethyl)pyridine molecules and dissolve them in 1 mL of isopropanol solution, stirring thoroughly to dissolve. Prepare a perovskite surface passivation layer in a glove box. Take 50 μL of the above solution and drop it onto the perovskite surface obtained in step (3), then spin-coat it to form a film. Specifically, the spin-coating speed is 4000 rpm and the spin-coating time is 30 s, performing a one-step spin-coating. After spin-coating, transfer the perovskite to a hot plate at 100 °C for annealing for 5 min, and then allow it to cool naturally to room temperature.

[0104] (5) Preparation of Spiro-OMeTAD hole transport layer: Weigh 73.2 mg of Spiro-OMeTAD in a glove box, dissolve it in 1 mL of chlorobenzene, and stir for 1 h. Then add 28.8 μL of 4-tert-butylpyridine and 17.6 μL of acetonitrile solution of LiTFSI (520 mg / mL). -1 Continue stirring for 1 hour. Take 30 μL of Spiro-OMeTAD chlorobenzene solution and add it dropwise to the perovskite film obtained in step (4) for spin coating. The spin coating speed is 3000 rpm and the spin coating time is 30 s. Then transfer the glass to a constant temperature and humidity chamber at 25℃ and 15% humidity for oxidization for 20 hours.

[0105] (6) Preparation of Au counter electrode: 100 mg Au was placed in a vacuum thermal evaporation apparatus and Au counter electrode was deposited on the thin film obtained in step (5) with the process parameters of evaporation rate of 0.05 nm / s, evaporation temperature of 900-1000℃ and evaporation time of 20-30 min. The thickness of Au counter electrode was 80 nm.

[0106] Performance testing

[0107] Compared with Comparative Examples 1 and 2, Examples 1-7 all achieved good optimization of perovskite film quality and device performance. Specifically, when annealing was performed using a conventional spin-coating method ( Figure 2 Left, Comparative Example 1) or when the pyridine passivation layer is introduced alone by solution spin coating ( Figure 2 In Comparative Example 2), lead iodide enrichment was clearly detected on the surface of the perovskite film, the perovskite grain boundaries were indistinct, and the film uniformity was poor. However, the perovskite film prepared using the solid-solid imprinting method (Example 1) did not show lead iodide on its surface, and the perovskite grains were larger, more complete and uniform, and more densely packed. Figure 2 (Right) This demonstrates that solid-solid imprinting can significantly suppress the precipitation of lead iodide, fundamentally solving the surface micro-degradation of perovskite during high-temperature annealing, thereby effectively improving the crystal quality and crystallinity of perovskite. Figure 3 ) and photoluminescence intensity ( Figure 4 Both achieved significant improvements, with the efficiency of perovskite photovoltaic devices fabricated by solid-solid imprinting increasing from 24.44% to 26.22%. Figure 5 The maximum power output stability reaches 1350 hours. Figure 6 ).

[0108] To further verify the scalability of the solid-solid imprinting method, this invention applied the solid-solid imprinting method to different process flows, all of which yielded good photovoltaic performance of the devices. Specifically, a pyridine solid layer was prepared by immersion method (Example 2), followed by solid-solid imprinting annealing. The perovskite film exhibited a similar microstructure to the spin-coated perovskite film (Example 1). Figure 7 The device efficiency and stability are similar, indicating that this solid-solid imprinting method can not only be matched with the laboratory small-area battery preparation process, but can also be extended to the preparation of large-area perovskite thin films, which is conducive to future large-scale production.

[0109] Example 3 further verified the above conclusions. This example used a solid-solid imprinting method to prepare a large-area (effective area 1 cm²) imprint. 2 The perovskite solar cell also exhibited a photoelectric conversion efficiency of 24.86%. Figure 8 ).

[0110] Example 4 investigated the reusability of the pyridine solid-state imprinted layer. Thirty perovskite films were formed using the same imprinted layer through solid-on-solid imprinting annealing, and then assembled into perovskite solar cells. Test results showed that all 30 devices exhibited excellent photoelectric conversion efficiency. Figure 9 (25%–26%). This indicates that during each imprinting process, solid-state imprinting molecules can selectively interact with the perovskite, rather than being indiscriminately imprinted onto the perovskite film. This selectivity avoids ineffective molecular coverage and improves the passivation effect of film defects. Simultaneously, it can also improve material utilization and reduce device fabrication costs.

[0111] Examples 5, 6, and 7 investigated the effects of solid-solid imprint annealing on different perovskite systems (MAPbI3, Cs). x FA 1-x PbI3, MA x FA 1-x Pb(I y Br 1-y The adaptability of the perovskite was observed, and its crystallinity and microstructure were found to be similar to those of the perovskite prepared in Example 1, with a significant improvement in film quality. Figure 10 This indicates that the solid-solid imprinting method used in this invention is not limited by the perovskite component system and has good universality.

[0112] In summary, this invention provides a solid-solid imprinting annealing process that simultaneously achieves uniform and dense growth of perovskite crystals and defect passivation within a confined space, effectively improving the quality of perovskite thin films and further enhancing the photovoltaic performance of perovskite solar cells. This method effectively avoids structural degradation of perovskite wet films caused by surface defects during traditional annealing, while passivating various defects in the perovskite thin film, improving the interfacial energy level structure, and enhancing carrier transport capabilities, thereby improving device efficiency and stability. Furthermore, the solid-solid imprinting annealing process of this invention is simple, the solid passivation layer can be reused multiple times, and it is suitable for large-area perovskite solar cells with different composition systems, possessing high versatility and commercial application prospects.

[0113] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the quality of polycrystalline perovskite crystals through solid-solid imprint annealing, characterized in that, First, a solid-state imprinted layer of pyridine molecules is prepared, wherein N in the pyridine molecule is associated with (CH2). x NH2 is in the ortho position, and it can be any one of 2-aminopyridine, 2-aminomethylpyridine, or 2-(2-aminoethyl)pyridine; Then, during the initial stage of perovskite annealing, a solid imprinted layer is applied to the surface of the perovskite wet film, and annealing is carried out under certain pressure and temperature conditions until the annealing process is completed; the initial stage of annealing is 1 to 5 minutes after the start of annealing. The method for improving the quality of polycrystalline perovskite crystals through solid-solid imprint annealing specifically includes the following steps: 1) Processing conductive glass: Cut the conductive glass to the required size and clean it for later use; 2) Preparation of tin dioxide electron transport layer: Prepare raw material solution and prepare tin dioxide thin film on glass treated in step 1) by chemical bath deposition method; 3) Preparation of pyridine solid imprint layer: Prepare pyridine isopropanol solution, coat the glass surface treated in step 1) with pyridine molecular layer, and then perform annealing treatment; 4) Preheating of the imprinted weights: Place the weights on the heating plate for preheating; 5) Preparation of perovskite thin film: Prepare a perovskite precursor solution and drop it onto the substrate treated in step 2) to prepare a wet film; 6) Solid-solid imprinting annealing: Under heating conditions, the pyridine solid imprinting layer prepared in step 3) is covered on the surface of the perovskite film, and the preheated weight in step 4) is pressed on the covering layer. Solid-solid imprinting is performed in the early stage of perovskite annealing until the perovskite annealing is completed, and the imprinting layer is removed.

2. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 1, characterized in that, The annealing temperature is 120~150℃, and the total annealing time is 10~30min; the pressure is 0.049~0.1225MPa.

3. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 1, characterized in that, Also includes: 7) Preparation of Spiro-OMeTAD hole transport layer: Prepare Spiro-OMeTAD chlorobenzene solution, coat it on the perovskite film prepared in step 6), and then place the film in a constant temperature and humidity drying oven for oxidation treatment. 8) Fabrication of metal counter electrode: A high work function metal counter electrode is deposited on the Spiro-OMeTAD thin film treated in step 7) using a vacuum thermal evaporation method.

4. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 3, characterized in that, The conductive glass mentioned in step 1) is selected from any one of ITO, FTO, PET / ITO, and PEN / ITO; the cleaning steps for the conductive glass include: The glass was ultrasonically cleaned sequentially with glass cleaning fluid, deionized water, acetone, ethanol and isopropanol, and then dried before being treated with a UV-ozone cleaner. The ultrasonic cleaning time was 15-20 minutes, and the UV-ozone cleaner treatment time was 15-30 minutes at a temperature of 20-30°C.

5. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 1, characterized in that, The preparation method of the raw material solution in step 2) is as follows: dissolve 2g of urea, 2mL of hydrochloric acid, 40uL of trifluoroacetic acid and 0.44g of SnCl2·2H2O in 160mL of deionized water; The chemical bath deposition method is as follows: the conductive glass substrate is immersed in the raw material solution, reacted at 90°C for 4 hours, the glass is taken out, ultrasonically cleaned with deionized water and isopropanol for 5 minutes respectively, rinsed with deionized water and ethanol, and then dried by nitrogen flow.

6. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 1, characterized in that, The pyridine concentration in the pyridine isopropanol solution mentioned in step 3) is 0.08~0.42 mol / L. The preparation method is as follows: take an appropriate amount of pyridine molecules and dissolve them in 1 mL of isopropanol, and stir to mix evenly. The pyridine isopropanol solution was applied to the glass surface treated in step 1) by spin coating or immersion coating. The spin coating method is as follows: take 50 μL of pyridine isopropanol solution, drop it onto the glass surface and spin coat to form a film; the spin coating speed is 500~3000 rpm and the spin coating time is 30~50 s; the immersion method is as follows: immerse the glass in pyridine isopropanol solution for 1~5 min; The annealing temperature is 80~120℃, and the annealing time is 5min.

7. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 1, characterized in that, The weights mentioned in step 4) are chrome-plated weights with a mass of 2-5 kg; the preheating temperature is 120-150℃ and the preheating time is 3-5 min. In step 5), the perovskite precursor solution is dropped onto the substrate treated in step 2), and a film is formed by spin-coating using a one-step anti-solvent method; wherein the spin-coating speed is 1000~5000 rpm, the spin-coating time is 10~50 s, and the anti-solvent is diethyl ether or chlorobenzene; The concentration of the perovskite precursor solution is 1.5~1.8 mol / L; the solvent system is a mixed solvent of DMF and DMSO, with a DMF:DMSO volume ratio of 4:1~9:1; The perovskite component is any one of FAPbI3, MAPbI3, CsPbI3, or ternary blend perovskite.

8. The method for improving the quality of polycrystalline perovskite crystals by solid-solid imprint annealing according to claim 3, characterized in that, The preparation method of the Spiro-OMeTAD chlorobenzene solution in step 7) is as follows: Dissolve 73.2 mg Spiro-OMeTAD in 1 mL of chlorobenzene and stir for 1 h, then add 28.8 μL of 4-tert-butylpyridine and 17.6 μL of 520 mg·mL⁻¹. -1 The acetonitrile solution of LiTFSI was stirred for another 1 hour. The spin coating speed is 3000 rpm, the spin coating time is 30 s; the drying oven temperature is 20~25℃, the humidity is 10~20%, and the oxidation time is 20 h; The metal mentioned in step 8) is Au or Ag; the evaporation rate is 0.005~0.2nm / s, the evaporation temperature is 900~1000℃, the evaporation time is 20~30min, and the electrode thickness is 60~90nm.

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