A device and method for preparing perovskite thin film by layer-by-layer deposition

Abstract

The present invention belongs to the technical field of solar cells, and particularly relates to a device and a preparation method for preparing a perovskite film by layer-by-layer deposition. The device comprises a main vacuum chamber, an embedded vacuum chamber and a vacuum pump. A plurality of high-temperature evaporation sources for carrying and evaporating lead salts are arranged in the main vacuum chamber. The embedded vacuum chamber is arranged in the main vacuum chamber. A shutter structure for isolating or connecting the main vacuum chamber and the embedded vacuum chamber is arranged at the bottom of the embedded vacuum chamber. The shutter structure is located above the high-temperature evaporation source. A substrate rack for placing a substrate and a heater for heating the substrate are arranged in the embedded vacuum chamber. The present invention adopts a method of embedding a vacuum chamber in the main vacuum chamber, and uses a shutter to isolate the two vacuum chambers, so that the perovskite film deposition process is divided into a plurality of cycles, thereby realizing layer-by-layer deposition and overcoming the difficulty that a two-step reaction method based on vapor deposition cannot accurately prepare a thick perovskite film.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a device and a method for preparing a perovskite film by layer-by-layer deposition. Background Art

[0002] Perovskite materials have attracted much attention due to their excellent optoelectronic properties. Perovskite materials can be used to prepare solar cells, photodetectors, light-emitting diodes and laser devices. In recent years, researchers have focused on the preparation of perovskite materials on the solution method. The solution method is to dissolve the perovskite precursor in an organic solvent, apply or spin-coat it, and then use a wind knife or vacuum distillation to treat it. This determines that its thickness can be adjusted in a very small range. In addition, toxic solvents are inevitably used in the preparation process of the solution method, which also hinders large-scale production. The use of the vapor phase method to prepare perovskite films can effectively avoid the use of toxic solvents and is also compatible with existing industrial processes. At present, there are two main ways to prepare perovskite films by vapor deposition, one is the co-evaporation method, and the other is a two-step reaction method based on vapor deposition. Since organic salt vapor is volatile and lead salt is directional, it is difficult to control the evaporation accuracy of co-evaporation. For the two-step reaction method of vapor deposition, this method is to obtain a perovskite film by reacting a lead salt film with an organic salt vapor. The thickness of the lead salt limits the diffusion of the organic salt vapor, which makes it impossible to prepare a thicker perovskite film. Therefore, it is very important to develop a device and method that can achieve the preparation of perovskite films of arbitrary thickness. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in order to solve the problem that the thickness of the perovskite thin film cannot be accurately controlled in the prior art, a device and a preparation method for preparing the perovskite thin film by layer-by-layer deposition are provided.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a device for preparing perovskite thin film by layer-by-layer deposition, the device comprises a main vacuum chamber, an embedded vacuum chamber and a vacuum pump, a plurality of high-temperature evaporation sources for carrying and evaporating lead salt are arranged in the main vacuum chamber, the embedded vacuum chamber is arranged in the main vacuum chamber, the embedded vacuum chamber can be provided with a heating device for heating the entirety, a shutter structure for isolating or connecting the main vacuum chamber and the embedded vacuum chamber is arranged at the bottom of the embedded vacuum chamber, the shutter structure is located above the high-temperature evaporation source, a substrate rack for placing a substrate and a heater for heating the substrate are arranged in the embedded vacuum chamber, a plurality of low-temperature evaporation sources for carrying and evaporating organic salt are arranged inside the embedded vacuum chamber, a pipe for rapid cooling is wound around the low-temperature evaporation source, the pipe is connected to an external device for transporting a cold medium, the embedded vacuum chamber and the main vacuum chamber are both connected to the vacuum pump by an exhaust pipeline, and a nitrogen inlet connected to an external gas source is arranged inside the embedded vacuum chamber. This scheme uses a shutter structure to isolate two vacuum chambers, divides the perovskite film deposition process into several cycles, and realizes layer-by-layer deposition, overcoming the problem that the two-step reaction method based on vapor deposition cannot accurately prepare thick perovskite films.

[0005] In some preferred embodiments, the shutter structure is an inter-lens shutter structure or a focal plane shutter structure.

[0006] In some preferred embodiments, a first valve is provided on the exhaust pipeline between the embedded vacuum chamber and the vacuum pump, a second valve is provided on the exhaust pipeline between the main vacuum chamber and the vacuum pump, and a third valve is provided on the nitrogen inlet.

[0007] In some preferred embodiments, the heater is an infrared heating lamp, a quartz lamp, a carbon lamp or a halogen lamp.

[0008] In some preferred embodiments, the plurality of low-temperature evaporation sources embedded in the vacuum chamber are evenly distributed around the substrate rack.

[0009] In some preferred embodiments, the high temperature evaporation source is provided with a first cover for blocking evaporation.

[0010] In some preferred embodiments, the low-temperature evaporation source is provided with a second cover for blocking evaporation.

[0011] The substrate rack is rotatably mounted in the embedded vacuum chamber.

[0012] In some preferred embodiments, the heating device comprises a heating wire arranged in an embedded vacuum chamber.

[0013] A method for preparing a device for preparing a perovskite film by layer-by-layer deposition, the method comprising the following steps:

[0014] S0. The substrate is placed on a substrate holder embedded in a vacuum chamber, and a lead salt is filled in a high-temperature evaporation source, and an organic salt is filled in a low-temperature evaporation source, and the first valve, the second valve and the third valve are in a closed state;

[0015] S1. Keep the first valve and the second valve open, evacuate the main vacuum chamber and the embedded vacuum chamber through the vacuum pump, and control the pressure range of the main vacuum chamber and the embedded vacuum chamber to be less than 5*10 -5 Pa;

[0016] S2. Open the shutter structure, and turn on the high temperature evaporation source, evaporate the lead salt using the high temperature evaporation source of the main vacuum chamber, and obtain a lead salt film on the substrate, the thickness of which is limited to about 50nm-200nm, and then turn off the high temperature evaporation source, cover the first cover to block the evaporation of the lead salt;

[0017] S3. Close the shutter structure and the second valve, turn on the heating device and heat the embedded vacuum chamber, the heating temperature range of the embedded vacuum chamber is limited to 70°C-100°C, open the third valve and introduce nitrogen into the nitrogen inlet, close the third valve after the nitrogen is introduced, and control the pressure range of the embedded vacuum chamber to be 20Pa-200Pa by the vacuum pump;

[0018] S4. Turning on the low-temperature evaporation source embedded in the vacuum chamber to evaporate the organic salt, and depositing the evaporated organic salt on the lead salt film to deposit an organic salt film, wherein the thickness of the deposited organic salt film ranges from about 50nm to 200nm;

[0019] S5. Turn off the low-temperature evaporation source, cover the second cover to block the evaporation of the organic salt, then introduce high-speed nitrogen into the wound tube, and reduce the temperature of the low-temperature evaporation source to 30°C-50°C;

[0020] S6. Open the third valve, introduce nitrogen into the embedded vacuum chamber through the nitrogen inlet, purge for 1min-3min, and then close the third valve;

[0021] S7. Repeat steps S2-S6, setting the number of repetitions to 2-5 times according to the actual thickness of the perovskite film to be obtained;

[0022] S8. Turn on the heater and form a perovskite film through an annealing process, the annealing temperature is 100°C-120°C, and the annealing time is 10min-20min. The lead salt film in step S2 and the organic salt film in step S4 are limited in deposition thickness, mainly to ensure that the two (lead salt film and organic salt film) can react and form a perovskite film during heating in the later stage. If the deposition thickness of the two (lead salt film and organic salt film) is not limited, the thickness of the two is too thick or too thin, which will cause the two to fail to react with each other to form a perovskite film, resulting in failure of the film to prepare the perovskite film.

[0023] The beneficial effects of the present invention are as follows: the present invention adopts a method of embedding a vacuum chamber in a main vacuum chamber, and utilizes a shutter structure to isolate the two vacuum chambers, thereby dividing the perovskite film deposition process into several cycles, realizing layer-by-layer deposition, and overcoming the difficulty that the two-step reaction method based on vapor deposition cannot accurately prepare thick perovskite films. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] Figure 1 It is a schematic diagram of the structure of the present invention;

[0026] Figure 2 is a SEM cross-sectional view of the perovskite film prepared in Example 1 of the present invention;

[0027] Figure 3 is a SEM cross-sectional view of the perovskite film prepared in Example 2 of the present invention;

[0028] Figure 4 This is a SEM cross-sectional view of the perovskite film prepared in Example 3 of the present invention.

[0029] In the figure: 1. main vacuum chamber, 2. embedded vacuum chamber, 3. high temperature evaporation source, 4. vacuum pump, 5. second valve, 6. shutter structure, 7. nitrogen inlet, 8. heater, 9. substrate holder, 10. low temperature evaporation source, 11. second cover, 12. pipe, 13. exhaust pipeline, 14. first valve, 15. third valve, 16. first cover. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with embodiments:

[0031] The present invention is not limited to the following specific embodiments. A person skilled in the art can implement the present invention in various other specific embodiments according to the contents disclosed in the present invention, or any simple changes or modifications made to the design structure and ideas of the present invention fall within the protection scope of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0034] Example 1

[0035] like Figure 1 As shown, a device for preparing a perovskite film by layer-by-layer deposition includes a main vacuum chamber 1 and an embedded vacuum chamber 2. A plurality of high-temperature evaporation sources 3 (heatable in the range of room temperature to 1200°C) for carrying and evaporating lead salts are arranged below the main vacuum chamber 1. Three to six high-temperature evaporation sources 3 can be arranged in the main vacuum chamber 1 according to actual conditions. The main vacuum chamber 1 is connected to a vacuum pump 4 through an exhaust pipe 13 and a second valve 5 is arranged on the exhaust pipe 13. The vacuum pump 4 is a cascade pump and can make the chamber vacuum reach 1*10 -5pa, the embedded vacuum chamber 2 is arranged in the main vacuum chamber 1 and is located on the top thereof, the distance between the high temperature evaporation source 3 and the embedded vacuum chamber 2 is 20cm-30cm, a shutter structure 6 for isolating or connecting the main vacuum chamber 1 and the embedded vacuum chamber 2 is installed at the bottom of the embedded vacuum chamber 2, the upper part of the embedded vacuum chamber 2 is a substrate rack 9, the substrate rack 9 is used to place the substrate, the substrate rack 9 is rotatable, a heater 8 is arranged above the substrate rack 9, a plurality of low temperature evaporation sources 10 (heatable range is room temperature to 600°C) for carrying and evaporating organic salts are evenly arranged around the substrate rack 9 inside the embedded vacuum chamber 2, the low temperature evaporation source 10 has a second cover 11 that can be sealed and used to block evaporation, and the high-temperature evaporation source 3 has a first cover 16 that can be sealed and used to block evaporation. In particular, a stainless steel pipe 12 is also wrapped around the outside of the low-temperature evaporation source 10. Nitrogen can be introduced into the stainless steel pipe 12 through an external device to quickly cool down the low-temperature evaporation source 10. Since it is very slow to cool down the low-temperature evaporation source 10 when it is closed in a vacuum environment, quickly cooling down the low-temperature evaporation source 10 is to prevent the organic salt from continuously volatilizing and causing waste. The embedded vacuum chamber 2 is connected to the vacuum pump 4 through an exhaust pipe 13 and a first valve 14 is provided on the exhaust pipe 13.

[0036] The shutter structure 6 can be an inter-lens shutter structure or a focal plane shutter structure, preferably an inter-lens shutter structure. The shutter structure 6 is semi-closed or sealed, preferably sealed, wherein the shutter structure 6 can also include a plurality of stainless steel blades hinged on the embedded vacuum chamber 2 to form a closed structure, and one end of the electric push rod is hinged on the embedded vacuum chamber 2, and then the other end of the electric push rod is hinged on the stainless steel blades, and the stainless steel blades are controlled to rotate simultaneously to realize the opening or closing of the inter-lens shutter.

[0037] The distance between the shutter structure 6 and the substrate is 6 cm.

[0038] The entire embedded vacuum chamber 2 can be heated by means of a serpentine armored heating wire welded to its inner wall. The heater 8 used for heating the substrate is an infrared heating lamp, and a quartz lamp, a carbon lamp, a halogen lamp, etc. can also be used. An infrared heating lamp with a fast thermal effect is preferred.

[0039] The low-temperature organic sources embedded in the vacuum chamber 2 are evenly distributed around the substrate rack 9, and six of them may be provided.

[0040] A nitrogen inlet 7 connected to an external gas source is provided inside the embedded vacuum chamber 2 , and a third valve 15 is provided on the nitrogen inlet 7 .

[0041] The specific steps for preparing perovskite thin films are as follows (taking a 10*10cm substrate as an example):

[0042] S0. Place a 10*10cm substrate on a substrate holder 9 embedded in a vacuum chamber 2, fill the required lead iodide in the high-temperature evaporation source 3, fill the required organic salt (methylammonium iodide) in the low-temperature evaporation source 10, and the first valve 14, the second valve 5 and the third valve 15 are in a closed state;

[0043] S1. The second valve 5 and the first valve 14 are both in the open state, and the main vacuum chamber 1 and the embedded vacuum chamber 2 are evacuated to 3*10 -4 Pa;

[0044] S2. Open the shutter structure 6 and turn on the high temperature evaporation source 3. The high temperature evaporation source 3 is heated to 700°C. The lead salt is evaporated by the high temperature evaporation source 3 of the main vacuum chamber 1. The lead salt includes lead iodide (PbI 2 ), and a lead salt film is prepared on the substrate, the film thickness is about 150nm, and then the first cover 16 of the high temperature evaporation source 3 is covered to block the evaporation of lead iodide;

[0045] S3. Close the shutter and the second valve 5, heat the embedded vacuum chamber 2 to 70°C, open the third valve 15, open the third valve 15 and introduce nitrogen into the nitrogen inlet 7, close the third valve 15 after the nitrogen is introduced, and adjust the opening of the first valve 14 on the exhaust pipe 13 of the embedded vacuum chamber 2, and control the pressure range of the embedded vacuum chamber 2 to about 20Pa through the vacuum pump 4;

[0046] S4. The low-temperature evaporation source 10 embedded in the vacuum chamber 2 is turned on to evaporate the organic salt, where the organic salt includes methyl ammonium iodide (MAI). The low-temperature evaporation source 10 is heated to 120°C, and the organic salt film 120nm is deposited on the lead salt film by controlling the evaporation time;

[0047] S5. The low-temperature evaporation source 10 is closed, and the second cover 11 on the low-temperature evaporation source 10 is covered to block the evaporation of the organic salt, and high-speed nitrogen is introduced into the stainless steel tube 12 wrapped around the low-temperature evaporation source 10 to rapidly cool it to 50°C;

[0048] S6. Keep the third valve 15 open, introduce nitrogen into the embedded vacuum chamber 2 through the nitrogen inlet 7 and purge for 3 min, and then close the third valve 15;

[0049] S7. Repeat steps S2-S6 once;

[0050] S8. Turn on heater 8, the annealing temperature is 120°C, and the plated PbI 2 The MAI / MAI stacked film was annealed for 10 min, and the two reacted to form a perovskite film with a thickness of about 300 nm.

[0051] Embodiment 2:

[0052] The difference between Example 2 and Example 1 is that steps 2-5 are repeated twice, and finally a perovskite film with a thickness of about 600 nm is obtained.

[0053] Embodiment 3:

[0054] The difference between Example 4 and Example 1 is that steps 2-5 are repeated 3 times, and finally a perovskite film with a thickness of about 900 nm is obtained.

[0055] Attached Figure 2-4 The SEM cross-sectional images are of the perovskite films prepared in Examples 1, 2 and 3, respectively. The thicknesses of the prepared films are: 300 nm in Example 1, about 600 nm in Example 2, and about 900 nm in Example 3.

[0056] The above-mentioned ideal embodiments of the present invention are for inspiration. Through the above-mentioned description, relevant staff can make various changes and modifications without departing from the technical idea of ​​the present invention. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A device for preparing perovskite thin films by layer-by-layer deposition, Features: The device comprises a main vacuum chamber (1), an embedded vacuum chamber (2) and a vacuum pump (4); a plurality of high-temperature evaporation sources (3) for carrying and evaporating lead salt are arranged in the main vacuum chamber (1); the embedded vacuum chamber (2) is arranged in the main vacuum chamber (1); a heating device for heating the embedded vacuum chamber (2) as a whole is arranged; a shutter structure (6) for isolating or connecting the main vacuum chamber (1) and the embedded vacuum chamber (2) is arranged at the bottom of the embedded vacuum chamber (2); the shutter structure (6) is located above the high-temperature evaporation source (3); and a vacuum pump (4) is arranged in the embedded vacuum chamber (2). A substrate rack (9) for placing a substrate and a heater (8) for heating the substrate are provided. A plurality of low-temperature evaporation sources (10) for carrying and evaporating organic salts are arranged inside the embedded vacuum chamber (2). A tube (12) for rapid cooling is wound around the low-temperature evaporation source (10). The tube (12) is connected to an external device for transporting a cold medium. The embedded vacuum chamber (2) and the main vacuum chamber (1) are both connected to a vacuum pump (4) via an exhaust pipeline (13). A nitrogen inlet (7) connected to an external gas source is arranged inside the embedded vacuum chamber (2).

2. The device for preparing a perovskite thin film by layer-by-layer deposition according to claim 1, Features: The shutter structure (6) is an inter-lens shutter structure or a focal plane shutter structure.

3. The device for preparing perovskite thin film by layer-by-layer deposition according to claim 1, Features: A first valve (14) is provided on the exhaust pipeline (13) between the embedded vacuum chamber (2) and the vacuum pump (4), a second valve (5) is provided on the exhaust pipeline (13) between the main vacuum chamber (1) and the vacuum pump (4), and a third valve (15) is provided on the nitrogen inlet (7).

4. The device for preparing a perovskite thin film by layer-by-layer deposition according to claim 1, Features: The heater (8) is one of an infrared heating lamp, a quartz lamp, a carbon lamp or a halogen lamp.

5. The device for preparing perovskite thin film by layer-by-layer deposition according to claim 1, Features: The plurality of low-temperature evaporation sources (10) in the embedded vacuum chamber (2) are evenly distributed around the substrate rack (9).

6. The device for preparing perovskite thin film by layer-by-layer deposition according to claim 1, Features: The high-temperature evaporation source (3) is provided with a first cover (16) for blocking evaporation.

7. The device for preparing perovskite thin film by layer-by-layer deposition according to claim 1, Features: The low-temperature evaporation source (10) is provided with a second cover (11) for blocking evaporation.

8. The device for preparing a perovskite thin film by layer-by-layer deposition according to claim 1, Features: The substrate rack (9) is rotatably mounted in the embedded vacuum chamber (2).

9. The device for preparing a perovskite thin film by layer-by-layer deposition according to claim 1, Features: The heating device comprises a heating wire arranged in the embedded vacuum chamber (2).

10. A method for preparing a device for preparing a perovskite film by layer-by-layer deposition according to any one of claims 1 to 9, It is characterized in that The preparation method comprises the following steps: S0. The substrate is placed on a substrate holder (9) in an embedded vacuum chamber (2), and a lead salt is filled into a high temperature evaporation source (3), and an organic salt is filled into a low temperature evaporation source (10), and the first valve (14), the second valve (5) and the third valve (15) are in a closed state; S1. Keep the first valve (14) and the second valve (5) open, evacuate the main vacuum chamber (1) and the embedded vacuum chamber (2) through the vacuum pump (4), and control the pressure range of the main vacuum chamber (1) and the embedded vacuum chamber (2) to be less than 5*10 -5 Pa; S2. Open the shutter structure (6), and turn on the high temperature evaporation source (3), evaporate the lead salt using the high temperature evaporation source (3) of the main vacuum chamber (1), and obtain a lead salt film on the substrate, the thickness of which is limited to 50nm-200nm, then turn off the high temperature evaporation source (3), and cover the first cover (16) to block the evaporation of the lead salt; S3. Close the shutter structure (6) and the second valve (5), turn on the heating device and heat the embedded vacuum chamber (2), the heating temperature range of the embedded vacuum chamber (2) is limited to 70°C-100°C, open the third valve (15) and introduce nitrogen into the nitrogen inlet (7), close the third valve (15) after the nitrogen is introduced, and control the pressure of the embedded vacuum chamber (2) to be in the range of 20Pa-200Pa through the vacuum pump (4); S4. Turning on the low-temperature evaporation source (10) embedded in the vacuum chamber (2) to evaporate the organic salt, and depositing the evaporated organic salt on the lead salt film to form an organic salt film, wherein the thickness of the deposited organic salt film is in the range of 50nm-200nm; S5. Turn off the low-temperature evaporation source (10), cover the second cover (11) to block the evaporation of the organic salt, then introduce high-speed nitrogen into the wound tube (12), and reduce the temperature of the low-temperature evaporation source (10) to 30°C-50°C; S6. Open the third valve (15), introduce nitrogen into the embedded vacuum chamber (2) through the nitrogen inlet (7), purge for 1min-3min, and then close the third valve (15); S7. Repeat steps S2-S6, setting the number of repetitions to 2-5 times according to the actual thickness of the perovskite film to be obtained; S8. Turn on the heater (8) to form a perovskite film through an annealing process, the annealing temperature is 100° C.-120° C., and the annealing time is 10 min to 20 min.

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