Method and equipment for directionally adjusting crystal face orientation of perovskite thin film

Abstract

The invention discloses a method for directionally adjusting the crystal face orientation of a perovskite film, and the method comprises the following steps: weighing perovskite precursor powder which comprises a perovskite material with the structural formula of ABX3; adding a mixed solvent of 2-ME, NMP, DMPU and DMSO into the perovskite precursor powder to prepare a perovskite precursor mixed solution with the concentration of 1.0 M; preparing a uniform perovskite solution wet film on the TCO substrate by using the perovskite precursor mixed solution through blade coating equipment or slit equipment to obtain a wet film substrate; and placing the wet film substrate in vacuum drying equipment, rapidly volatilizing the solvent through rapid vacuum pumping, and simultaneously introducing process steam to crystallize the perovskite to form the film. Therefore, the crystal face orientation of the perovskite thin film can be directionally adjusted, and the crystal face orientation is specifically optimized towards a higher carrier mobility direction and towards a lower defect state density direction. The photoelectric conversion efficiency of perovskite industrialization can be improved, and the method has a very considerable application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and in particular to a method and equipment for directionally adjusting the crystal plane orientation of a perovskite film. Background Art

[0002] With the continuous breakthroughs in the efficiency of perovskite academia, the advancement of the perovskite industry is also accelerating. The amazing progress of perovskite is due to the continuous improvement of the perovskite film preparation process. It mainly includes the following aspects: the continuous iterative progress of large-area slit coating equipment, the preparation of dense and void-free perovskite films, the application of small molecule perovskite passivation layers, and the development of targeted packaging technologies.

[0003] Although the development of perovskites is extremely rapid, the deeper understanding of the perovskite light-absorbing layer is still not thorough, especially the research on crystal structure and crystal plane orientation is still lacking. In the promotion of perovskite industrialization, large-area preparation is an urgent problem to be solved. How to prepare large-area void-free perovskite films has made certain progress under the joint efforts of many slit coating equipment manufacturers. With the continuous deepening of research, we found that on large-area perovskite films at the square meter level, the crystal plane orientation of perovskites is difficult to maintain consistency and it is difficult to achieve uniform crystallization. The delay time of the coating head and tail, the uncertainty of the order and direction of crystallization, and the annealing atmosphere fumigation will all hinder the large-area preparation of perovskite films with good orientation. How to maintain the consistency of crystal plane orientation on large-area perovskite films is a new challenge. . Summary of the invention

[0004] The purpose of the present invention is to provide a method for directionally adjusting the crystal plane orientation of the perovskite film, and optimizing the crystal plane orientation in a targeted manner toward a higher carrier mobility and a lower defect state density. The process and method of the present invention can improve the photoelectric conversion efficiency of the perovskite industrialization and have a very promising application prospect.

[0005] According to one aspect of the present invention, a method for directionally adjusting the crystal plane orientation of a perovskite film is provided, comprising the following steps:

[0006] Weighing perovskite precursor powder, wherein the perovskite precursor includes a perovskite material with a structural formula of ABX3; adding a mixed solvent of 2-ME, NMP, DMPU and DMSO to the perovskite precursor powder to prepare a perovskite precursor mixed solution with a concentration of 1.0M; passing the perovskite precursor mixed solution through a scraping device or a slit device to prepare a uniform perovskite solution wet film on a TCO substrate to obtain a wet film substrate; placing the wet film substrate in a vacuum drying device, rapidly evacuating the solvent to evaporate it, and simultaneously introducing a process steam body to allow the perovskite to crystallize into a film.

[0007] The beneficial effect is that the general structural formula of perovskite is ABX3, and the conventional band gap perovskite solute ratio that conforms to the general structural formula is applicable to the present invention. In terms of solvent formulation, 2-ME in the solvent ratio is very volatile, which plays a role in coordinating ventilation and regulating crystallization, and NMP and DMSO can effectively form ligands with the solute of perovskite, and can spontaneously crystallize and nucleate into black phase perovskite in VCD, and then assisted by the device and process described in the present invention, the crystal orientation can be effectively directional and directional.

[0008] In some embodiments, in the perovskite material having the structural formula ABX3, A is a cation Rb + ,Cs + ,FA + ,MA + One or more of, B is a cation Pb 2+ ,Sn 2+ One or more of, X is an anion C l - ,Br - , I - One or more of .

[0009] In some embodiments, A comprises MA + , Cs + and FA + ; B is Pb 2+ ; The structural formula of the perovskite material is MA a Cs b FA c Pb(I d Br e )3; where a, b, c have a range of values ​​in the interval [0, 1], d, e have a range of values ​​in the interval [0, 1], and a+b+c=1; d+e=1.

[0010] In some embodiments, a is 0.05, b is 0.05, c is 0.9, d is 0.95, and c is 0.05.

[0011] In some embodiments, the ratio of the mixed solvent is: 2-ME: NMP: DMPU: DMSO = 400: 20: 40: 40. The beneficial effect is that 2-ME in the solvent ratio is very volatile, and plays a role in coordinating ventilation and regulating crystallization, NMP and DMSO can effectively form ligands with the solute of perovskite, and can spontaneously crystallize and nucleate into black phase perovskite in VCD, and then with the assistance of the device and process of the present invention, the crystal orientation can be directionally adjusted.

[0012] In some embodiments, the process vapor is steam capable of forming perovskite ligands; or a reducing gas; or water vapor.

[0013] According to another aspect of the present invention, a vacuum drying device for implementing the aforementioned method for directionally adjusting the crystal plane orientation of a perovskite thin film includes a vacuum drying chamber for placing a wet film substrate; a multi-channel gas pipeline system composed of a plurality of pipelines connected to the top of the vacuum drying chamber; a vacuum pump located on one side of the vacuum drying chamber and connected thereto; and a steam generating device located on the other side of the vacuum drying chamber and connected thereto, wherein the steam generating device is respectively provided with solvent storage tanks capable of generating different types of gases, and each of the solvent storage tanks is respectively connected to each pipeline of the multi-channel gas pipeline system.

[0014] In some embodiments, the channel gas piping system includes

[0015] A plurality of first ventilation pipes arranged in parallel, each of which is provided with a first ventilation hole; a plurality of second ventilation pipes arranged in parallel, one end of each of which is vertically connected to each of the first ventilation pipes through each of the first ventilation holes, and the other end of each of the second ventilation pipes is connected to the vacuum chamber; a third ventilation pipe, one end of which is connected to the steam generating device, and the other end of which is connected to the first ventilation pipe.

[0016] In some embodiments, the first ventilation duct is arranged along the length direction of the vacuum drying chamber.

[0017] In some embodiments, the steam generating device is provided with a gas flow controller.

[0018] In some embodiments, the first ventilation duct is provided with a gas flow controller; and / or the second ventilation duct is provided with a gas flow controller; and / or the third ventilation duct is provided with a gas flow controller. The beneficial effect is: effectively controlling the gas flow, and being able to better adjust the crystal orientation.

[0019] Beneficial effects of the present invention: The technical solution of the present application can place the perovskite solution wet film substrate in the vacuum drying chamber through the vacuum pumping device, vacuum drying chamber and steam generating device connected in sequence, and cooperate with the multi-channel gas pipeline system. The vacuum pumping device can perform vacuum treatment on the perovskite solution wet film substrate, and by adjusting the gas entering the vacuum drying chamber, the various devices cooperate with each other to achieve rapid volatilization of the solvent of the perovskite wet film, effectively regulate the crystallization process, dynamically and directionally adjust the crystallization orientation of the perovskite film, reduce the uneven crystallization during the preparation of large-area perovskites, reduce grain boundary defects, improve crystallization performance, improve the quality of large-area perovskite films, and thus improve the photoelectric conversion efficiency of perovskite components. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of the vacuum drying equipment of this application;

[0021] Figure 2 for Figure 1 A schematic diagram of a top view structure;

[0022] Figure 3 This is the XRD characterization diagram of the perovskite film of Example 2;

[0023] Figure 4 This is the XRD characterization diagram of the perovskite film of Example 2.

[0024] Among them, 1-vacuum drying chamber; 2-glass substrate; 3-vacuum extraction device; 4-steam generating device; 5-multi-channel gas pipeline system; 51-first ventilation pipeline; 52-first ventilation hole; 53-second ventilation pipeline; 54-third ventilation pipeline

[0025] 6-Solvent storage tank; 7-Fourth ventilation pipeline; 8-Fifth ventilation pipeline DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the present invention is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work, such as conventional perovskite formulas, are generally applicable to the present invention and belong to the scope of protection of the present invention. The present invention is further described in detail below in conjunction with the accompanying drawings.

[0027] Example 1

[0028] Step 1: Weigh the perovskite precursor powder. The molecular formula of the perovskite precursor solution is as follows: 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 ) 3, the specific formula of each component is:

[0029] Cs I is 19.5 mg; MABr is 8.4 mg; FAI is 219.5 mg; Pb I2 is 659.5 mg; PbBr2 is 27.5 mg;

[0030] Step 2: Add an appropriate amount of 2-ME, NMP, DMPU, and DMSO mixed solvent to the weighed drug powder in step 1. The ratio of the mixed solvent is: 2-ME: NMP: DMPU: DMSO = 400: 20: 40: 40. Specifically, 2-ME: 800 μL, NMP: 40 μL, DMPU: 80 μL, DMSO: 80 μL, to prepare a perovskite precursor mixed solution with a concentration of 1.0 M. Place the above mixed solution on a stirring table and stir at room temperature for 4 hours to fully dissolve it to obtain a perovskite precursor mixture;

[0031] The solvent ratio is shown in the following table:

[0032] Example Solvent Ratio 2-ME 400 NMP 20 DMPU 40 DMSO 40

[0033] Step 3: Prepare a uniform wet film of perovskite solution on the TCO substrate by using the above perovskite precursor mixture through a scraping device or a slit device; wherein scraping or slit is only a method of forming a film of perovskite precursor solution, and its usual speed is 1m / min, as long as the film can be formed uniformly.

[0034] Step 4: The wet film substrate in step 3 is introduced into the vacuum drying chamber 1 of the vacuum drying equipment of the present invention, and vacuum treatment is performed by the vacuum pumping device 3. The vacuum degree is reduced to below 0.5 Pa within 50-100 seconds. During the operation of the vacuum drying equipment, the steam of the main solvent of perovskite 2-ME / DMSO in the steam generating device is appropriately introduced into the vacuum drying chamber; the specific steam flow rate is: 1000-3000sccm.

[0035] Step 5: Evaporate C60, BCP and Cu on the perovskite substrate prepared above.

[0036] Specifically, as attached Figure 1-2 As shown, the vacuum drying equipment comprises

[0037] The vacuum drying chamber 1 is used to place the glass substrate 2; the vacuum drying chamber 1 is connected to a multi-channel gas pipeline system 5 composed of multiple pipelines.

[0038] A vacuum device 3, located at one side of the vacuum drying chamber 1 and connected thereto;

[0039] The steam generating device 4 is located at the other side of the vacuum drying chamber 1 and is connected thereto, wherein the steam generating device 4 is provided with solvent storage tanks capable of generating different types of gases, and each of the solvent storage tanks 6 is connected to each pipeline of the multi-channel gas pipeline system 5, respectively.

[0040] Among them, A shown in the figure 1-4 , B 1-4 , C1-4 , D 1-4 Sampling points for experimental testing.

[0041] In addition, the solvent stored in the solvent storage tank 6 is related to the formula of the perovskite precursor solution, and can be an oxidizing gas, a reducing gas, a perovskite solvent vapor, etc. For example, if it is an easily oxidized perovskite (such as tin-based perovskite, lead-tin blended perovskite), an appropriate amount of reducing gas can be introduced to inhibit the oxidation process; if the perovskite component contains reagents such as MACL that need to react with water for crystallization, the effect of regulating crystallization can be achieved by adjusting the gas with different humidity during the vacuum drying process; if some perovskite components require high-temperature reaction or the crystallization process requires temperature-assisted crystallization, gases of different temperatures can be introduced to directionally assist crystallization.

[0042] In the present application, the perovskite solvent vapor of 2-ME / DMSO, the main solvent of the perovskite in the steam generating device, can better make up for the difference before and after drying in the large-area preparation process.

[0043] The multi-channel gas pipeline system 5 includes a first ventilation pipe 51, which is transversely arranged above the vacuum drying chamber 1, and a plurality of first ventilation holes 52 are evenly opened at the bottom of the first ventilation pipe 51; a plurality of second ventilation pipes 53 arranged in parallel, one end of each of the second ventilation pipes 53 is vertically connected to the first ventilation pipe 51 through the first ventilation hole 52, and a plurality of third ventilation pipes 54 arranged in parallel, which are arranged in parallel along the length direction of the vacuum drying chamber, and the other end of each of the second ventilation pipes 53 is correspondingly connected to the top of the third ventilation pipe 54; the bottom of the third ventilation pipe 54 is evenly opened with air outlet holes along the length direction. The first ventilation pipe 51 is provided with a gas flow controller; and / or the second ventilation pipe 53 is provided with a gas flow controller; and / or the third ventilation pipe 54 is provided with a gas flow controller.

[0044] Example 2 (reference sample)

[0045] Different from Example 1, the vacuum drying equipment of the present invention is not used in step 4, that is, there is no steam generating device 4, and steam is not introduced into the vacuum drying chamber during the vacuum treatment.

[0046] The effects between Example 1 and Example 2 are characterized as follows:

[0047] Figure 33 is the XRD characterization diagram corresponding to the perovskite film prepared in Example 2; it can be seen from the figure that at different vacuum spans, the crystal orientation changes significantly, the diffraction peak intensity of the (100) crystal plane orientation of the AD perovskite gradually becomes lower, while the diffraction peak intensity of the (110) / (220) crystal plane orientation gradually becomes stronger, confirming the invention that the perovskite crystal quality has a large difference with the order of crystallization, and the crystal orientation changes significantly in the direction of the vacuum gas flow.

[0048] Figure 4 3 is the XRD characterization diagram corresponding to the perovskite film prepared in Example 1; it can be seen from the figure that under different vacuum gas flow directions, the XRD diffraction peak crystallization intensity and orientation are almost unchanged, the (100) crystal plane orientation diffraction peak intensity of the perovskite at each test point AD does not change much, and the (110) / (220) crystal plane orientation diffraction peak intensity does not change significantly, which confirms that, under the application of the device of the present invention, with the assistance of the crystallization control atmosphere, the uniformity of perovskite crystallization can be significantly improved, and the control of crystallization orientation can be significantly improved.

[0049] It is thus proved that the vacuum drying equipment applied for in the present invention can directionally adjust the crystal plane orientation of the perovskite film. The equipment is a vacuum drying equipment for gas-assisted crystallization. Since a process link in the preparation of the perovskite absorption layer requires the use of a vacuum drying equipment, the main function of the vacuum drying equipment is to allow the perovskite wet film to be evenly dried. The vacuum drying equipment in the prior art can only achieve basic process conditions such as the pressure of the adjustment equipment and the pumping speed of the vacuum pump. The perovskite drying process is closely related to the subsequent grain growth and annealing crystallization, and simple process adjustment equipment cannot meet the role of regulating the perovskite crystal orientation. Especially in the drying of large-area perovskite films prepared at the square meter level (taking 1.2m*0.6m as an example), the existing ordinary vacuum equipment has a large difference in the crystal orientation near and far from the vacuum pump port.

[0050] Therefore, the device of the present application adds multi-channel gas pipelines within the range of square meters, which are distributed above the entire vacuum drying chamber. Figure 1-2 In a drying path within a large range, each ventilation duct can independently adjust the airflow direction, thereby significantly reducing the problem of inconsistent crystal orientation caused by the large difference in crystallization time before and after.

[0051] As attached Figure 1, A to D in the vacuum drying chamber 1 are several experimental sampling points with increasing distances from the vacuum exhaust port of the vacuum exhaust device 3. In ordinary vacuum drying devices, there is obvious directionality in the crystallization sequence of AD, and because the entire membrane surface is too large (square meter level), the difference in the crystallization time of AD can reach 10-30s. The specific difference varies with different equipment and is also affected by different perovskite solution formulas.

[0052] The device of the present invention cooperates with the vacuum device 3, the vacuum drying chamber 1, the steam generating device 4 and the multi-channel gas pipeline system 5. The multi-channel gas pipelines added within the range of square meters are distributed above the entire process chamber. Figure 1-2 In a large range of drying paths, each air distribution pipeline can independently adjust the airflow direction, thereby significantly reducing the problem of inconsistent crystal orientation caused by the large difference in crystallization time before and after. Figure 4 shown.

[0053] The above disclosure is only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the invention.

Claims

1. A method for directional adjustment of the crystal plane orientation of a perovskite film, characterized in that: The following steps are involved: Weighing a perovskite precursor powder, wherein the perovskite precursor comprises a perovskite material having a structural formula of ABX3; Adding 2-ME, NMP, DMPU, and DMSO mixed solvent to the perovskite precursor powder to prepare a perovskite precursor mixed solution with a concentration of 1.0 M; The perovskite precursor mixed solution is passed through a doctor blade device or a slit device to prepare a uniform perovskite solution wet film on a TCO substrate to obtain a wet film substrate; The wet film substrate is placed in a vacuum drying device, and the solvent is rapidly evaporated by vacuum treatment, while process steam is introduced to allow the perovskite to crystallize into a film.

2. The method according to claim 1, characterized in that In the perovskite material with the structural formula ABX3, A is a cation Rb + ,Cs + ,FA + ,MA + One or more of, B is a cation Pb 2+ ,Sn 2+ One or more of, X is an anion Cl - ,Br - , I - One or more of .

3. The method according to claim 2, characterized in that A contains MA + , Cs + and FA + ; B is Pb 2+ ; The structural formula of the perovskite material is MA a Cs b FA c Pb(I d Br e )3; Among them, the value range of a, b, c is [0,1], the value range of d, e is [0,1], and a+b+c=1; d+e=1.

4. The method according to claim 3, characterized in that A is 0.05, b is 0.05, c is 0.9, d is 0.95, and c is 0.

05.

5. The method according to claim 1, characterized in that The ratio of the mixed solvent is: 2-ME: NMP: DMPU: DMSO = 400: 20: 40:

40.

6. The method according to claim 1, characterized in that The process steam body is steam capable of forming perovskite ligands; or reducing gas; Or water vapor.

7. The method according to claim 1, characterized in that The vacuum treatment comprises: Within 50-100 seconds, the vacuum degree is below 0.5Pa.

8. A vacuum drying device for implementing the method for directional adjustment of the crystal plane orientation of a perovskite film according to any one of claims 1 to 7, characterized in that: include The vacuum drying chamber is used to place the glass substrate; the top of the vacuum drying chamber is connected to a multi-channel gas pipeline system composed of multiple pipelines. A vacuum pumping device, located at one side of the vacuum drying chamber and connected thereto; The steam generating device is located at the other side of the vacuum drying chamber and is connected thereto, wherein the steam generating device is provided with solvent storage tanks capable of generating different types of gases, and each of the solvent storage tanks is connected to each pipeline of the multi-channel gas pipeline system.

9. The vacuum drying equipment according to claim 8, characterized in that: The multi-channel gas pipeline system (5) comprises A first ventilation duct (51), the first ventilation duct (51) being arranged transversely above the vacuum drying chamber (1), and a plurality of first ventilation holes (52) being evenly arranged at the bottom of the first ventilation duct (51); A plurality of second ventilation pipes (53) are arranged in parallel, one end of each of the second ventilation pipes (53) being vertically connected to the first ventilation pipe (51) through the first ventilation hole (52). A plurality of third ventilation ducts (54) are arranged in parallel, wherein the third ventilation ducts are arranged in parallel along the length direction of the vacuum drying chamber, and the other end of each of the second ventilation ducts (53) is correspondingly connected to the top of the third ventilation duct (54); and the bottom of the third ventilation duct (54) is evenly provided with air outlet holes along the length direction.

10. The vacuum drying equipment according to claim 9, characterized in that: Also includes A fourth ventilation duct (7) has one end connected to the steam generating device (4) and the other end connected to the first ventilation duct (51).

11. The vacuum drying equipment according to claim 9, characterized in that: Also includes A fifth ventilation duct (8) has one end connected to the vacuum drying chamber (1) and the other end connected to the vacuum extraction device (3).

12. The vacuum drying equipment according to claim 9, characterized in that: The first ventilation pipeline (51) is provided with a gas flow controller; and / or the second ventilation pipeline (53) is provided with a gas flow controller; And / or the third ventilation pipeline (54) is provided with a gas flow controller.

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