Perovskite thin film and preparation method and device thereof

Abstract

The application belongs to the technical field of perovskite film preparation, and particularly relates to a perovskite film and a preparation method and device thereof. 1 X and B 2 X2 is dissolved in an organic solvent to form a precursor solution, the precursor solution is coated on a substrate, dried, and then the substrate is immersed in a liquid medium for first annealing to obtain an inorganic skeleton layer; (2) the precursor AX is evaporated onto the inorganic skeleton layer to form an organic layer, and then the organic layer is immersed in a liquid medium for second annealing. The perovskite film prepared by the method has good uniformity and crystallinity, the crystal grains in the film are uniform in shape, large in size, and good in compactness, and the film layer has few holes, which helps to improve the transmission of electrons and thus improves the efficiency and stability of the device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of perovskite thin film preparation, and particularly relates to a perovskite thin film and a preparation method and device thereof. BACKGROUND

[0002] As a new field in the thin-film solar cell technology, perovskite solar cells have the characteristics of high efficiency potential, low cost, and wide application scenarios, and have become the research focus in the global photovoltaic field. The extensive research on perovskite solar cell devices with large area, high efficiency and high stability has enabled the rapid industrialization of this new photovoltaic technology.

[0003] A perovskite solar cell device is composed of transparent glass, a transparent conductive layer (bottom electrode), a hole transport layer, a perovskite layer, an electron transport layer, and an upper electrode. The typical perovskite layer is an ABX3 type organic and inorganic material, A generally refers to an organic amine ion, B generally refers to a metal ion, and X generally refers to a halogen ion or a variety of halogen doping. The thickness of the perovskite layer is generally 300 nm-1000 nm. The perovskite layer plays a crucial role in the entire battery structure, and the quality of the film directly affects the generation and transport of electrons and holes, thereby affecting the photoelectric conversion efficiency, stability, and service life of the battery.

[0004] The quality of the perovskite film layer depends on its crystallization method and process. An ideal perovskite thin film has uniform grain shape, large grain size, and high density. At present, an ideal perovskite thin film is usually prepared by a heating annealing method. The perovskite is dissolved in a solvent according to a certain stoichiometric ratio, prepared on a substrate by a spin coating method, and then placed on a flat heater for annealing to form a thin film. However, this traditional preparation method has some drawbacks, such as (1) the flat plate heating annealing process is from bottom to top, i.e. the heat is first transferred from the hot plate to the substrate and then to the perovskite layer, resulting in a delay in heating the surface of the thin film, which causes uneven heating of the perovskite layer in the thickness direction, to some extent, hinders the uniform linear growth of the perovskite crystal, and affects the crystallization quality and density of the film layer; (2) the spin coating method forms a film by high-speed centrifugal rotation, and the presence of centrifugal force can cause the film layer to form an uneven surface with a thin middle and thick periphery, which is more obvious in large-area industrial production. Therefore, how to improve the crystallization quality and density of the perovskite thin film caused by annealing has become one of the research focuses in the field. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to overcome the defects of poor crystallization quality and density of the perovskite thin film in the prior art, and to provide a perovskite thin film and a preparation method and device thereof.

[0006] To this end, the present application provides the following technical solutions.

[0007] The application provides a preparation method of a perovskite thin film, comprising the following steps,

[0008] (1) perovskite precursor B 1 X and B 2 X2 is dissolved in an organic solvent to form a precursor solution, the precursor solution is coated on a substrate, dried, and then the substrate is immersed in a liquid medium for first annealing to obtain an inorganic skeleton layer;

[0009] (2) evaporating the precursor AX to the inorganic skeleton layer to form an organic layer, and then immersing the organic layer in a liquid medium for second annealing;

[0010] Wherein, A is at least one of amine ions and amidine ions;

[0011] B 1 is at least one of cesium ions, potassium ions and sodium ions;

[0012] B 2 is at least one of lead ions and tin ions;

[0013] X is at least one of iodine ions, bromine ions and chlorine ions.

[0014] The liquid medium is at least one of dipropylene glycol methyl ether and propylene glycol butyl ether;

[0015] Preferably, the organic solvent is dimethylformamide.

[0016] The preparation method meets at least one of A-B,

[0017] A, in the step (1), the temperature of the liquid medium is 130-160 DEG C;

[0018] Preferably, the time for the substrate to be immersed in the liquid medium is 1-3 min;

[0019] B, in the step (2), the temperature of the liquid medium is 150-170 DEG C;

[0020] Preferably, the time for the organic layer to be immersed in the liquid medium is 10-26 min.

[0021] In the preparation method, the B 1 is cesium ions;

[0022] The B 2 is lead ions;

[0023] The A includes at least one of methylamine ions and formamidine ions;

[0024] The X includes at least one of iodine ions and bromine ions.

[0025] The preparation method satisfies at least one of A-B,

[0026] A, in the step (2), the evaporation is performed under the condition that the vacuum degree is not less than 5*10 -4 Pa.

[0027] Preferably, the deposition rate is 0.1-0.6nm / s when the evaporation is performed.

[0028] Preferably, the thickness of the organic layer is 200-450nm.

[0029] B, in the step (1), the coating step is performed by using a slot coating method.

[0030] Preferably, the total molar concentration of B 1 X and B 2 X2 in the precursor solution is 1-2mol / L.

[0031] Preferably, the thickness of the inorganic skeleton layer is 200-450nm.

[0032] The parameters of the slot coating method are as follows: the coating liquid feeding speed is 150-200μL / s, the platform moving speed is 30-100mm / s, and the gap between the coating head and the platform is 180-300μm.

[0033] In the preparation of the inorganic skeleton layer, the amount ratio of B 1 X and B 2 X2 is not specifically limited, and the molar ratio of B 1 and B 2 may be 1:10, 1:5, 2:5, etc., and any ratio between these values. In the preparation of the organic layer, the amount ratio of the amine group ion and the amidine group ion is not specifically limited, and the molar ratio of the amine group ion and the amidine group ion may be but not limited to 1:1, 1:2, 1:3, etc., and any ratio between these values. As long as the final product is a perovskite thin film, the ABX3 relationship is satisfied, wherein B includes B 1 and B 2 .

[0034] Methylamine particles (MA + ), formamidine particles (FA + )

[0035] The preparation method of the substrate comprises,

[0036] (1) forming an ITO layer or an FTO layer on a substrate to obtain a conductive substrate;

[0037] (2) depositing a nickel-containing oxide on the ITO layer or the FTO layer to form a transport layer, and annealing.

[0038] The thickness of the ITO layer or FTO layer is 90-200nm;

[0039] Preferably, the thickness of the transport layer is 15-30nm;

[0040] Preferably, the annealing is performed at 280-330℃;

[0041] Preferably, the annealing time is 50-80min;

[0042] Preferably, the substrate is transparent glass.

[0043] The substrate used in the present application can be obtained commercially or self-made. Further, an ITO layer or FTO layer is formed on the substrate by a magnetron sputtering method to obtain a conductive substrate; then a nickel-containing oxide (NiO X ) is deposited on the ITO layer or FTO layer by a magnetron sputtering method to form a transport layer, and annealing is performed to obtain the substrate. The conductive substrate can be obtained by the method described above or obtained commercially.

[0044] The present application provides a perovskite thin film prepared by the preparation method.

[0045] In addition, the present application also provides a perovskite thin film annealing device suitable for the first annealing step and / or the second annealing step in the preparation method;

[0046] The perovskite thin film annealing device comprises,

[0047] An annealing container, which is suitable for filling or discharging a liquid medium;

[0048] A substrate support (9) is arranged in the annealing container, and the substrate support (9) is suitable for supporting a perovskite film layer (100);

[0049] A heater (8) is arranged at the bottom of the substrate support (9), and the heater (8) is suitable for heating to a preset temperature when the liquid medium is filled into the annealing container.

[0050] The technical scheme of the present application has the following advantages:

[0051] 1. The preparation method of the perovskite thin film provided by the present application, which comprises (1) preparing a perovskite precursor B 1 X and B 2X2 is dissolved in an organic solvent to form a precursor solution, the precursor solution is coated on a substrate, dried, and then the substrate is immersed in a liquid medium for first annealing to obtain an inorganic skeleton layer; (2) the precursor AX is evaporated onto the inorganic skeleton layer to form an organic layer, and then the organic layer is immersed in a liquid medium for second annealing. The perovskite film prepared by the method has good uniformity and crystallinity, the crystal grains in the film are uniform in shape, large in size, and good in compactness, the holes in the film layer are few, which helps to improve the transmission of electrons, and thus the efficiency and stability of the device are improved.

[0052] Compared with the traditional flat plate annealing method, the present application performs annealing in a liquid medium, heat can be quickly transferred to the perovskite layer, the perovskite layer is uniformly heated, a uniform and dense film layer is formed, and thus the efficiency and stability of the device are improved. At the same time, the solution annealing method used in the present application can also greatly shorten the annealing time, improve the production efficiency, extract the residual organic solvent in the film layer, reduce the impurity content in the film layer, and improve the purity of the perovskite; further, performing annealing in a liquid medium can also ensure that the perovskite films prepared in each batch have good repeatability.

[0053] The present application adopts a step-by-step film forming method, first forms a stable and dense inorganic skeleton layer on a substrate, then evaporates an organic layer on the inorganic skeleton layer, and performs second annealing, the organic components in the organic layer react with the inorganic components in the inorganic skeleton layer, the organic components gradually diffuse into the inorganic layer, and a perovskite layer with extremely high uniformity is formed, which further ensures the uniformity, compactness and stability of the perovskite film and improves the crystalline quality of the film.

[0054] The present application combines the step-by-step film forming method with annealing in a liquid medium, which can ensure the formation of a perovskite film with uniform density and high crystalline quality, and thus improves the efficiency and stability of the device.

[0055] 2. The preparation method of the perovskite film provided by the present application uses dipropylene glycol methyl ether and / or propylene glycol butyl ether as the liquid medium for annealing, which can extract impurities such as organic solvents remaining in the perovskite, and obtain a perovskite layer with higher purity. Compared with benzene-based media, the present application uses dipropylene glycol methyl ether and / or propylene glycol butyl ether as the liquid medium for annealing, which has a higher boiling point, a wider available annealing temperature range, and can use a higher annealing temperature to make the film layer better crystallize, shorten the annealing time, and the chemical properties of the two liquid media are stable, which are environmentally friendly materials and less harmful to people and the environment.

[0056] Further, by controlling the temperature of the liquid medium in steps (1) and (2), the temperature of the first annealing and the second annealing is further controlled, wherein the temperature of the liquid medium in step (1) is controlled to be 130-160 DEG C, which is helpful to form the inorganic skeleton layer without affecting the crystallization rate of the perovskite; in step (2), the organic layer is formed on the inorganic skeleton layer by evaporation, and when the second annealing is performed, the organic component in the organic layer and the inorganic component in the inorganic skeleton layer can react chemically, and by controlling the temperature of the liquid medium to be 160-170 DEG C, the reaction can be more sufficient and the reaction rate can be accelerated.

[0057] 3. The perovskite thin film annealing device provided by the application comprises an annealing container, a substrate support, and a heater, wherein the annealing container is adapted to be filled with or drained of a liquid medium; the substrate support is arranged in the annealing container and is adapted to support the perovskite film layer; and the heater is arranged at the bottom of the substrate support and is adapted to be heated to a preset temperature when the liquid medium is filled into the annealing container. The heater in the annealing device heats the liquid medium, and a direct contact and four-way conduction rapid annealing mode is provided, so that the annealing time can be shortened and the annealing efficiency can be improved. The heat can be quickly transferred to the perovskite layer, the heating is uniform, a uniform and dense film is formed, the perovskite thin film is uniformly annealed, the annealing time is shortened, and the production efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0059] Figure 1 Fig. 1 is a schematic diagram of the annealing device provided by the embodiment 1 of the application;

[0060] Figure 2 Fig. 2 is a schematic diagram of the annealing drawer in the annealing device;

[0061] Figure 3 Fig. 3 is a schematic diagram of the annealing groove in the annealing device;

[0062] Figure 4 Fig. 4 is a SEM scanning electron microscope of the perovskite thin film prepared in the embodiment 2 of the application;

[0063] Figure 5 Fig. 5 is a SEM scanning electron microscope of the perovskite thin film in the comparative example 1;

[0064] Legend of the drawings:

[0065] 1-pipe, 2-circulating pump, 3-constant temperature storage tank, 4-one-way valve, 5-filter, 6-sealing box, 7-annealing drawer, 8-heater, 9-substrate support, 10-one-way liquid level valve, 11-inlet end, 12-outlet end, 13-annealing tank, 14-top cover, 100-perovskite film layer. DETAILED DESCRIPTION

[0066] The following examples are provided to better further understand the present application, and are not limited to the best mode, and do not constitute limitations on the content and scope of protection of the present application, and any person under the inspiration of the present application or the combination of the present application with other prior art features, any product identical or similar to the present application falls within the scope of protection of the present application.

[0067] In the examples, the specific experimental steps or conditions are not specified, which can be operated according to the conventional experimental steps described in the literature or the conditions. The reagents or instruments used are not specified by the manufacturer, which are conventional reagent products that can be obtained by market purchase.

[0068] Example 1

[0069] The present embodiment provides an annealing device used for the first annealing step and the second annealing step in Examples 2-4, referring to Figures 1-2 , the annealing device comprises:

[0070] An annealing container, which is suitable for filling or discharging liquid medium;

[0071] A substrate support 9 is arranged in the annealing container, and the substrate support 9 is suitable for supporting the perovskite film layer 100; wherein the perovskite film layer 100 specifically refers to the perovskite dry film in step (1) and / or the substrate after forming the organic layer in step (2) in Examples 2-4, and then performing the first annealing to form the inorganic skeleton layer or performing the second annealing to form the organic layer.

[0072] A heater 8 is arranged at the bottom of the substrate support 9, and the heater 8 is suitable for heating to a preset temperature when the liquid medium is filled into the annealing container. The preset temperature specifically refers to the temperature of the liquid medium in each example. The perovskite thin film annealing device fills the liquid medium into the annealing container, and heats the liquid medium by the heater 8 when the liquid medium is filled into the annealing container, which provides a direct contact and four-way conduction rapid annealing mode, can shorten the annealing time, improve the annealing efficiency, the heat can be quickly transferred to the perovskite layer, and the heating is uniform, which is easy to form a uniform and dense film, and solves the problem of uneven annealing in the thickness direction of the perovskite thin film.

[0073] Specifically, the heater 8 is suitable for heating to the preset temperature of the liquid medium when the liquid medium is filled into the annealing container.

[0074] Before the annealing device works, the heating and temperature control device matched with the constant-temperature storage tank 3 needs to be started for preheating a long time in advance to ensure that the temperature of the liquid medium meets the requirements.

[0075] Specifically, the annealing container is provided with an inlet end 11 suitable for the inflow of the liquid medium and an outlet end 12 suitable for the outflow of the liquid medium.

[0076] Specifically, the inlet end 11 is arranged at a position opposite to the outlet end 12 in the height direction. Figure 2 As shown in the figure, the inlet end 11 and the outlet end 12 are located on the same side of the annealing container, and specifically can be located at two top corner positions of the same side.

[0077] After the liquid medium enters the inlet end 11, the annealing container will be gradually filled with the liquid medium, at this time, the outlet end 12 is in a closed state. When the annealing is completed, the outlet end 12 is opened, and the liquid medium is discharged from the outlet end 12.

[0078] The perovskite thin film annealing device further comprises:

[0079] The constant-temperature storage tank 3 is suitable for storing the liquid medium.

[0080] The liquid outlet of the constant-temperature storage tank 3 is directly or indirectly communicated with the inlet end 11 via the pipeline 1, and the liquid inlet of the constant-temperature storage tank 3 is directly or indirectly communicated with the outlet end 12 via the pipeline 1.

[0081] Specifically, the perovskite thin film annealing device comprises at least two annealing containers, and the at least two annealing containers are arranged in a stacked manner in the height direction.

[0082] The inlet end 11 of each annealing container is connected in parallel and communicated with the liquid outlet of the constant-temperature storage tank 3, and the outlet end 12 of each annealing container is connected in parallel and communicated with the liquid inlet of the constant-temperature storage tank 3.

[0083] Optionally, a one-way liquid level valve 10 is connected to the inlet end 11 of each annealing container, so as to facilitate the individual control of the inlet end 11 of each annealing container, to control the flow direction of the liquid medium, so as to set single-layer or multi-layer drawers for annealing according to the situation. Through the design of the multi-layer crystallization tank structure, batch production of perovskite thin films is facilitated.

[0084] Specifically, the perovskite thin film annealing device further comprises:

[0085] The circulating pump 2 is arranged between the liquid outlet of the constant-temperature storage tank 3 and the inlet end 11, and is suitable for pumping the liquid medium in the constant-temperature storage tank 3 into the annealing container.

[0086] A one-way valve 4 is arranged between the liquid inlet of the constant-temperature storage tank 3 and the outlet end 12, and is adapted to cut off or open the flow passage of the annealing container towards the constant-temperature storage tank 3.

[0087] When the one-way valve 4 is closed, the liquid medium can flow into the annealing container from the inlet end 11 and be kept in the annealing container for annealing operation. When the one-way valve 4 is opened, the liquid medium can be discharged from the outlet end 12 of the annealing container and flow into the constant-temperature storage tank 3 for reuse.

[0088] Specifically, the perovskite thin film annealing device further comprises:

[0089] A filter 5 is arranged between the outlet end 12 and the one-way valve 4, and is adapted to filter the liquid medium flowing back from the annealing container to the constant-temperature storage tank 3. By arranging the filter 5, the liquid medium can be filtered to facilitate reuse and reduce material waste.

[0090] Specifically, the annealing container comprises an annealing drawer 7.

[0091] The perovskite thin film annealing device further comprises a sealed box body 6, and the annealing drawer 7 is arranged in the sealed box body 6. By arranging the sealed box body 6 and the annealing drawer 7 in the sealed box body 6, multiple annealing drawers 7 can be arranged in the sealed box body 6 to facilitate batch production.

[0092] Optionally, when the annealing drawer 7 is pushed into the sealed box body 6, it can be sealed with the periphery of the sealed box body 6 to avoid liquid leakage. It also has good heat preservation effect to maintain constant temperature and ensure uniform annealing of the perovskite thin film.

[0093] Specifically, the pipeline 1 in the sealed box body 6 and connected to the outlet end 12 and the inlet end 11 of the annealing drawer 7 is a flexible pipe, which is adapted to move with the pulling movement of the annealing drawer 7.

[0094] Optionally, the liquid pipeline is composed of two parts, namely a hard pipe connected outside the box body and a flexible pipe connected between the annealing drawer and the sealed box body 6, to facilitate pulling of the annealing drawer 7.

[0095] As a variation, in combination with Figure 3 As shown in the figure, the annealing container can also be an annealing tank 13, and the annealing tank 13 is open at the upper end and provided with a top cover 14 at the opening position. The top cover 14 can be opened or closed relative to the annealing tank 13 to realize sealing of the annealing tank 13.

[0096] The specific working process of the perovskite film annealing device is as follows:

[0097] In the working state, the annealing drawer 7 is pulled out in turn, and the substrate is placed stably on the substrate support 9, so that the film layer on the substrate is not blocked by the frame of the substrate support. Then, the annealing drawer is pushed into the sealed box body 6 to form a closed space. The one-way valve 4 is closed, and the circulating pump 2 is started to extract the liquid medium in the constant-temperature storage tank 3, so that the liquid medium flows into each annealing drawer 7 from the inlet end 11 at the upper end of the annealing drawer 7 in turn. At the same time, the heater 8 at the bottom of the annealing box is started to make the liquid medium reach the preset temperature. With the addition of the liquid medium, the liquid medium gradually covers the substrate until it covers about 1 cm. The circulating pump 2 stops working, and the film layer on the substrate anneals and crystallizes in the constant-temperature liquid solution. After a certain time of annealing, the one-way valve 4 is opened, the heater 8 at the bottom of the annealing box is closed, and the liquid medium flows out from the outlet end 12 at the lower end of the annealing drawer 7 through the filter 5 and enters the constant-temperature storage tank 3. The liquid medium is ready for the next cycle of use. The annealing drawer 7 is pulled out, and the perovskite assembly that has been annealed is taken out. The above steps are repeated.

[0098] Example 2

[0099] The embodiment provides a preparation method of a perovskite film, which comprises the following steps,

[0100] (1) CsI, PbI2 and PbBr2 are dissolved in a DMF organic solvent at a molar ratio of 1:2:3 to prepare a first precursor solution with a total concentration of 1 mol / L. The first precursor solution contains inorganic components Pb 2+ , Cs + , Br - , I -then the first precursor solution is coated on the substrate by slot-die coating to form a perovskite wet film, and then the perovskite wet film is placed in a vacuum crystal preparation device, a vacuum pump is started, and is kept for 40 s to obtain a perovskite dry film. The substrate is placed on a substrate support, and dipropylene glycol methyl ether is used as a liquid medium, and is introduced into the annealing container at a speed of 12 L / min from the inlet end to contact the substrate. The temperature of the dipropylene glycol methyl ether is 145 ℃. Before the perovskite dry film is immersed, the substrate can be preheated to reduce the generation of stress in the annealing process, avoid the formation of a large stress due to the difference in the thermal expansion coefficient between the substrate and the perovskite film, and prevent the problem of mismatching between the substrate and the perovskite film and the breakage of the perovskite film. After the dipropylene glycol methyl ether is about 1 cm above the substrate, the introduction of the dipropylene glycol methyl ether is stopped, and the first annealing is started. The immersion time of the substrate in the dipropylene glycol methyl ether is 2 min, and then the dipropylene glycol methyl ether flows out of the outlet end and into a constant-temperature storage tank for recycling. Nitrogen is used to blow away the liquid remaining on the substrate, and the first annealing is ended. After natural cooling in clean air, the inorganic skeleton layer is obtained. The parameters of the slot-die coating method are as follows: coating liquid inlet speed: 150 μL / s, platform moving speed: 40 mm / s, gap between the coating head and the platform: 200 μm, and inorganic skeleton layer thickness: 350 nm.

[0101] (2) MAI and FAI are mixed in a molar ratio of 1:1, ball-milled in a planetary ball mill for 10 h to form a uniform solid-phase mixture, and the solid-phase mixture is evaporated onto the inorganic skeleton layer by a thermal evaporation method to form an organic layer. The vacuum degree is set to 5 x 10 -4 Pa, deposition rate: 0.1-0.6 nm / s, organic layer thickness: 350 nm, and after evaporation is completed, the substrate is taken out and placed on a substrate support. Dipropylene glycol methyl ether is used as a liquid medium, and is introduced into the annealing container at a speed of 12 L / min from the inlet end to contact the substrate. The temperature of the dipropylene glycol methyl ether is 160 ℃. After the dipropylene glycol methyl ether is about 1 cm above the organic layer, the introduction of the dipropylene glycol methyl ether is stopped, and the second annealing is started. The time for which the dipropylene glycol methyl ether is above the organic layer is 15 min, and then the dipropylene glycol methyl ether flows out of the outlet end and into a constant-temperature storage tank for recycling. Nitrogen is used to blow away the liquid remaining on the substrate, and the second annealing is ended. After natural cooling in clean air, the perovskite thin film is obtained.

[0102] The substrate used in the embodiment is self-made, and the preparation method comprises the following steps: taking commercially available FTO conductive glass as a conductive substrate, the model of which is FTO-N11-10 and the size of which is 100*100*1.1mm, then preparing a 24nm-thick NiO hole transport layer on the conductive substrate by a magnetron sputtering method, and annealing to obtain the substrate after cooling; wherein, a flat plate annealing device is used to perform annealing in clean air, the annealing temperature is 300℃, and the annealing time is 60min.

[0103] Example 3

[0104] The embodiment provides a preparation method of a perovskite film, which comprises the following steps,

[0105] (1) CsI, CsBr, PbI2 and PbBr2 are dissolved in a DMF organic solvent according to a molar ratio of 3:2:15:10 to prepare a first precursor solution with a total concentration of 1.2mol / L, then the first precursor solution is coated on the substrate by a slit coating method to form a perovskite wet film, and the perovskite wet film is placed in a vacuum crystal preparation device, a vacuum pump is started, and the vacuum pump is kept for 40s to obtain a perovskite dry film. The substrate is placed on a substrate support, propylene glycol butyl ether is used as a liquid medium, the propylene glycol butyl ether enters an annealing container from an inlet end at a speed of 12L / min and is in contact with the substrate, the temperature of the propylene glycol butyl ether is 130℃, the propylene glycol butyl ether is stopped from being introduced after the propylene glycol butyl ether is about 1cm high above the substrate, first annealing is started, the immersion time of the substrate in the propylene glycol butyl ether is 2.5min, then the propylene glycol butyl ether flows out from an outlet end and enters a constant-temperature storage tank for recycling; nitrogen is used to blow away the residual liquid on the substrate, the first annealing is ended, and the inorganic skeleton layer is obtained after natural cooling in clean air. The parameters of the slit coating method are as follows: coating liquid feeding speed: 150μL / s, platform moving speed: 50mm / s, gap between the coating head and the platform: 220μm, and the thickness of the inorganic skeleton layer: 400nm.

[0106] (2) FAI and FABr are mixed according to a molar ratio of 3:2, and the mixture is ball milled in a planetary ball mill for 10 hours to form a uniform solid-phase mixture, the solid-phase mixture is evaporated onto the inorganic skeleton layer by a thermal evaporation method to form an organic layer, the vacuum degree is set to 5*10 -4Pa, deposition rate: 0.1-0.6 nm / s, organic layer thickness 400 nm, after the evaporation is completed, it is taken out and then placed on a substrate holder, propylene glycol butyl ether is used as a liquid medium, enters the annealing container from the inlet end at a speed of 12 L / min, and contacts the substrate, the temperature of the propylene glycol butyl ether is 155°C, after the propylene glycol butyl ether is immersed in the organic layer by about 1 cm, the propylene glycol butyl ether is stopped from being input, the second annealing is started, the time for the propylene glycol butyl ether to immerse the organic layer is 20 min, then the propylene glycol butyl ether flows out from the outlet end and enters a constant-temperature storage tank for recycling; nitrogen is used to blow away the liquid remaining on the substrate, the second annealing is ended, and the perovskite film is obtained after natural cooling in clean air. The substrate used in this embodiment is the same as that in embodiment 1.

[0107] Embodiment 4

[0108] The embodiment provides a preparation method of a perovskite film, including the following steps,

[0109] (1) CsI, PbI2 and PbBr2 are dissolved in a DMF organic solvent at a molar ratio of 2:5:5 to form a first precursor solution with a total concentration of 1.5 mol / L, then the first precursor solution is coated on a substrate by a slot coating method to form a perovskite wet film, and the perovskite wet film is placed in a vacuum crystal preparation device, a vacuum pump is started, and 40 s are kept to obtain a perovskite dry film. The substrate is placed on a substrate holder, dipropylene glycol methyl ether is used as a liquid medium, enters the annealing container from the inlet end at a speed of 12 L / min, and contacts the substrate, the temperature of the dipropylene glycol methyl ether is 140°C, after the dipropylene glycol methyl ether is immersed in the substrate by about 1 cm, the dipropylene glycol methyl ether is stopped from being input, the first annealing is started, the substrate is immersed in the dipropylene glycol methyl ether for 3 min, then the dipropylene glycol methyl ether flows out from the solution outlet and enters a constant-temperature storage tank for recycling; nitrogen is used to blow away the liquid remaining on the substrate, the first annealing is ended, and the inorganic skeleton layer is obtained after natural cooling in clean air. The parameters of the slot coating method are as follows: coating liquid input speed: 150 μL / s, platform moving speed: 60 mm / s, gap between the coating head and the platform 260 μm, and inorganic skeleton layer thickness: 420 nm.

[0110] (2) MAI and FAI are mixed at a molar ratio of 1:1, ball milled in a planetary ball mill for 10 hours to form a uniform solid-phase mixture, the solid-phase mixture is evaporated onto the inorganic skeleton layer by a thermal evaporation method to form an organic layer, the vacuum degree is set to 5x10 -4Pa, deposition rate: 0.1-0.6 nm / s, organic layer thickness 420 nm, after the evaporation is completed, it is taken out and then placed on a substrate support, with dipropylene glycol methyl ether as a liquid medium, at a speed of 12 L / min from the inlet end into the annealing container, in contact with the base, the temperature of the dipropylene glycol methyl ether is 165℃, after the dipropylene glycol methyl ether is about 1 cm high above the organic layer, stop feeding the dipropylene glycol methyl ether, start the second annealing, the time for the dipropylene glycol methyl ether to immerse the organic layer is 20 min, then the dipropylene glycol methyl ether flows out from the outlet end into the constant-temperature storage tank for recycling; use nitrogen to blow away the liquid remaining on the base, after the second annealing is completed, the perovskite thin film is obtained after natural cooling in clean air. The base used in this embodiment is the same as that in embodiment 1.

[0111] Comparative Example 1

[0112] The present comparative example provides a method for preparing a perovskite thin film, comprising the following steps,

[0113] FAI, CsI, PbI2 and PbBr2 are dissolved in DMF organic solvent according to a molar ratio of 4:1:2:3 to prepare a perovskite precursor solution with a total concentration of 1 mol / L, then the perovskite precursor solution is coated on the substrate by using a slot coating method to form a perovskite wet film, and the perovskite wet film is placed in a vacuum crystal preparation device, a vacuum pump is started, and the pressure is kept at 40 s to obtain a perovskite dry film. The temperature of the flat plate annealing device is set to 145℃, the substrate coated with the perovskite dry film is placed on the flat plate annealing device after the set temperature is reached to start annealing, the annealing time is set to 20 min, and the perovskite thin film is obtained after natural cooling in clean air after the annealing is completed.

[0114] Test Example

[0115] The present test example provides performance testing and results of the perovskite thin films prepared in the embodiments and comparative examples, which are as follows,

[0116] (1) Figure 4 is a SEM scanning electron microscope of the perovskite thin film prepared in embodiment 2, from which it can be seen that the perovskite thin film prepared in the present application can form dense and large-sized crystal grains, the crystal grain size is about 2 μm, and the perovskite thin film has few impurities on the surface. Figure 4

[0117] is a SEM scanning electron microscope of the perovskite thin film prepared in comparative example 1, from which it can be seen that the perovskite thin film has defects such as non-dense and loose. Figure 5 Figure 5

[0118] ​​(2) Characterization method of perovskite film stability: Fullerene (electron transport layer) with a thickness of 20 nm, bathocuproine (blocking layer) with a thickness of 6 nm and metal copper (electrode) with a thickness of 200 nm are sequentially evaporated on the perovskite film to form a perovskite device after encapsulation. The initial photoelectric conversion efficiency of the device is tested by using a photoelectric conversion efficiency tester, and the test results are shown in Table 1. Then the device is placed in an aging oven with a temperature of 85℃ and a humidity of 85%, and the photoelectric conversion efficiency of the device is tested again after being placed for 1000h. The test results are shown in Table 1. The photoelectric conversion efficiency attenuation of the device prepared in Example 2-4 is ≤10%, indicating that the perovskite film has good stability. The aging oven provides a dark and light-free environment.

[0119] Table 1 Test results of photoelectric conversion efficiency of devices in Examples 2-4

[0120] Example Initial conversion efficiency (%) Conversion efficiency after aging (%) Example 2 19.1 17.9 Example 3 18.3 16.9 Example 4 18.5 17.2

[0121] Obviously, the above examples are only examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted here. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing a perovskite thin film, characterized by, comprising the following steps, (1) perovskite precursor B 1 X and B 2 X2 is dissolved in an organic solvent to form a precursor solution, the precursor solution is coated on a substrate, dried, and then the substrate is immersed in a liquid medium for first annealing to obtain an inorganic skeleton layer; the temperature of the liquid medium is 130-160°C, and the substrate is immersed in the liquid medium for 1-3 min; (2) evaporating the precursor AX to form an organic layer on the inorganic skeleton layer, and then immersing the organic layer in a liquid medium for second annealing; the temperature of the liquid medium is 150-170℃, and the time for which the organic layer is immersed in the liquid medium is 10-26min; wherein A is at least one of amine ions and amidine ions; B 1 is at least one of cesium ion, potassium ion and sodium ion; B 2 at least one of a lead ion and a tin ion; X is at least one of iodine ions, bromine ions and chlorine ions; the liquid medium is at least one of dipropylene glycol methyl ether and propylene glycol butyl ether, and the organic solvent is dimethylformamide.

2. The production method according to claim 1, characterized by, The B 1 is a cesium ion; The B 2 is a lead ion; the A includes at least one of methylamine ions and formamidine ions; the X includes at least one of iodine ions and bromine ions.

3. The preparation method according to claim 1, characterized in that, at least one of a-b is satisfied, a. In step (2), the vapor deposition is carried out under a vacuum degree of not less than 5×10 -4 It was carried out under the condition of Pa; b. in the step (1), the coating step is performed by using a slot coating method.

4. The production method according to claim 3, characterized by, at least one of c-d is satisfied, c. in the step (2), when the evaporation is performed, the deposition rate is 0.1-0.6nm / s; d. In step (1), B in the precursor solution 1 X and B 2 The total molar concentration of X2 is 1-2 mol / L.

5. The preparation method according to claim 4, characterized in that, at least one of e-f is satisfied, e. in the step (2), the thickness of the organic layer is 200-450nm; f. in the step (1), the thickness of the inorganic skeleton layer is 200-450nm.

6. The preparation method according to claim 3, characterized in that, The parameters of the slot coating method are: coating liquid feeding speed: 150-200μL / s, platform moving speed: 30-100mm / s, gap between coating head and platform: 180-300μm.

7. The method of any one of claims 1-6, wherein, The preparation method of the substrate comprises, (1) forming an ITO layer or an FTO layer on a substrate to obtain a conductive substrate; (2) depositing a nickel-containing oxide on the ITO layer or the FTO layer to form a transport layer, and annealing.

8. The preparation method according to claim 7, characterized in that, The thickness of the ITO layer or the FTO layer is 90-200nm.

9. The preparation method according to claim 8, characterized in that, The thickness of the transport layer is 15-30nm.

10. The method of claim 8, wherein, The transport layer annealing is performed at 280-330℃.

11. The preparation method according to claim 8, characterized in that, The time for the transport layer annealing is 50-80min.

12. The method of claim 8, wherein, The material of the substrate is transparent glass.

13. A perovskite film prepared by the preparation method of any one of claims 1-12.

14. A perovskite thin film annealing apparatus, characterized by comprising: The perovskite film is suitable for use in the first annealing step and / or the second annealing step of the preparation method of any one of claims 1-12. The perovskite film annealing device comprises, an annealing container, which is adapted to be filled with or discharged from a liquid medium; a substrate holder (9) disposed in the annealing container, which is adapted to support a perovskite film layer (100); a heater (8) disposed at the bottom of the substrate holder (9), which is adapted to be heated to a preset temperature when the liquid medium is filled into the annealing container.

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