Preparation method and preparation equipment for improving uniformity of perovskite thin film

Abstract

The invention discloses a preparation method for improving the uniformity of a perovskite film. The preparation method comprises the following steps: paving a perovskite precursor solution on a substrate; placing the substrate with the wet film on a spin-coating machine for spin-coating, adding an anti-solvent in the form of atomized gas, covering the wet film with the anti-solvent, and carrying out full contact reaction with the wet film; carrying out annealing treatment on the substrate to form a perovskite thin film; the invention further discloses preparation equipment for implementing the preparation method. According to the method, the anti-solvent is added on the wet film in an atomization mode, non-uniformity of gradient distribution of the anti-solvent in the radial direction of the wet film is inhibited and reduced, and uniformity of perovskite crystal grain nucleation is improved, so that a perovskite thin film with a microstructure and uniformly distributed photoelectric characteristics can be better prepared, and an efficient perovskite solar cell is obtained; practical tests and production prove that the perovskite solar cell has high repeatability and process reliability, and the uniformity, repeatability and process reliability of the perovskite solar cell on a larger area are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of perovskite solar cells and a preparation device thereof, in particular to a preparation method of improving the uniformity of perovskite thin film and a preparation device thereof. BACKGROUND

[0002] Metal halide perovskite solar cells (PSCs) as the third generation of solar cell technology, due to its high photoelectric conversion efficiency (PCE) and low manufacturing cost, low preparation process difficulty, has obtained extensive research and development. In the process of pursuing high-efficiency perovskite solar cells, it is crucial to prepare high-quality perovskite thin film. Forming perovskite thin film with full coverage, uniform distribution of grains with suitable size, microstructure and photoelectric property uniformity, and good surface morphology on the effective cell area can inhibit the recombination of photo-generated carriers in the thin film, which is the key to obtaining high-efficiency perovskite solar cells.

[0003] The current solution method is the mainstream preparation method of high-efficiency perovskite solar cells. In this preparation method, the use of anti-solvent to quickly remove the solvent in the wet film has been formed to promote the formation of perovskite thin film. However, in the process of wet spin coating preparation, the anti-solvent is usually dropped at the center of the wet film. The gradient non-uniform distribution of the anti-solvent in the radial direction of the wet film makes the perovskite grain nucleation form a non-uniform spatial distribution, which ultimately leads to the non-uniform distribution of the microstructure and photoelectric properties of the perovskite thin film, and more uncontrollable defects occur. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of perovskite thin film of perovskite solar cells, which improves the uniformity of perovskite thin film and prepares perovskite thin film with uniform distribution of microstructure and photoelectric properties. The second purpose of the present application is to provide a preparation device for realizing the preparation method, which can repeatedly prepare perovskite thin film to obtain high-efficiency perovskite solar cells and has high reliability.

[0005] Technical scheme: A preparation method for improving the uniformity of perovskite thin film, comprising the following steps:

[0006] Step S10: spreading perovskite precursor solution on the substrate;

[0007] Step S20: placing the substrate with wet film on the spin coater for spin coating, and adding anti-solvent in the form of atomized gas to cover the wet film and fully contact and react with it;

[0008] Step S30: annealing the substrate to form a perovskite thin film.

[0009] Further, the gas flow of the anti-solvent atomized gas is 1-15 ml / min, and the reaction time is not more than 10 s.

[0010] Furthermore, the anti-solvent is one of chlorobenzene, anisole, and toluene.

[0011] Furthermore, the spin coating is performed by first performing low-speed spin coating and then high-speed spin coating. The rotation speed of the low-speed spin coating is 500-2000 rpm, the acceleration is 100-300 rpm / s, and the time is 5-15 s. The rotation speed of the high-speed spin coating is 4000-5500 rpm, the acceleration is 100-300 rpm / s, and the time is 10-30 s. When the countdown of the entire spin coating process does not exceed 10 s, the anti-solvent atomizing gas is introduced to fully contact and react with the wet film.

[0012] Furthermore, the annealing temperature is 100-130° C., and the annealing time is 10-30 minutes.

[0013] A preparation device for realizing the above-mentioned preparation method for improving the uniformity of perovskite thin film, the preparation equipment of step S20 includes an atomizer, an antisolvent tube, a compressed nitrogen tube, a gas pipe, a nozzle, and a spin coater, the antisolvent tube and the compressed nitrogen tube are respectively connected to the atomizer, one end of the gas pipe is connected to the atomizer, and the other end of the gas pipe is connected to the nozzle inlet, the spin coater is located below the nozzle outlet, the substrate with a wet film is placed on the spin coater, and the atomized gas formed at the nozzle outlet covers the wet film.

[0014] Furthermore, the preparation equipment also includes a robot, and the atomizer, nozzle, and spin coater are all connected and installed at the front end of the robot. Driven by the robot, the preparation equipment can be connected to the operating equipment of the previous and next process links to transfer the substrate.

[0015] Furthermore, the center of the nozzle is aligned with the center of the wet film, the distance between the nozzle outlet and the wet film is 0.5 to 1.5 cm, and the pressure of the atomizing gas ejected from the nozzle outlet is 0 to 100 psi.

[0016] Beneficial effects: The perovskite film preparation method and preparation equipment of the present invention adopt an atomization method to add an anti-solvent to the wet film, thereby suppressing and reducing the uneven gradient distribution of the anti-solvent in the radial direction of the wet film, and improving the uniformity of perovskite grain nucleation, so as to better prepare a perovskite film with uniform distribution of microstructure and photoelectric properties, and obtain efficient perovskite solar cells. It has been proved through actual tests and production that it has high repeatability and process reliability, and improves the uniformity, repeatability and process reliability of perovskite solar cells over a larger area. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the preparation equipment structure;

[0018] Figure 2 The perovskite solar cell structure prepared for a specific embodiment;

[0019] Figure 3 Microscopic morphologies of the perovskite thin film layers obtained in Examples 1 to 3 and Comparative Example 1 obtained through SEM testing: (a) center of Comparative Example 1, (b) edge of Comparative Example 1, (c) center of Example 1, (d) edge of Example 1, (e) center of Example 2, (f) edge of Example 2, (g) center of Example 3, and (h) edge of Example 3;

[0020] Figure 4 The electrical performance tests of the perovskite solar cells prepared using Examples 1 to 3 and Comparative Example 1 were conducted to measure: (a) efficiency distribution at the cell position, and (b) intra-cell non-uniformity. DETAILED DESCRIPTION

[0021] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0022] A preparation method for improving the uniformity of a perovskite film comprises the following steps:

[0023] Step S10: spreading the perovskite precursor solution on the substrate surface to form a wet film;

[0024] Step S20: Place the substrate with the wet film on a spin coater, first spin-coat at low speed and then spin-coat at high speed, the rotation speed of the low-speed spin coating is 500-2000 rpm, the acceleration is 100-300 rpm / s, and the time is 5-15 s, and the rotation speed of the high-speed spin coating is 4000-5500 rpm, the acceleration is 100-300 rpm / s, and the time is 10-30 s. When the countdown of the entire spin coating process does not exceed 10 s, the anti-solvent is introduced in the form of atomized gas and covers the wet film, and begins to fully contact and react with the wet film. The gas flow rate of the atomized gas is 1-15 ml / min until the reaction is completed.

[0025] The anti-solvent is one of chlorobenzene, anisole, and toluene.

[0026] Step S30: annealing the substrate obtained in step S20 to form a perovskite film, wherein the annealing temperature is 100-130° C. and the annealing time is 10-30 minutes.

[0027] The present invention completes step S20 by a specific preparation device. Figure 1As shown, the antisolvent atomization equipment includes an atomizer 1, an antisolvent tube 2, a compressed nitrogen tube 3, an air supply tube 4, a nozzle 5, a spin coater 6, and a manipulator 7. The atomizer 1 is respectively connected to the antisolvent tube 2 and the compressed nitrogen tube 3. One end of the air supply tube 4 is connected to the atomizer 1, and the other end of the air supply tube 4 is connected to the inlet of the nozzle 5. The antisolvent is transported into the atomizer through the antisolvent tube, and the compressed nitrogen is transported into the atomizer through the compressed nitrogen tube. In the atomizer, the compressed nitrogen serves as a transport carrier for the antisolvent. The antisolvent forms an atomized gas under the action of the compressed nitrogen and is ejected from the outlet of the nozzle 5 through the air supply tube. The spin coater 6 is located below the outlet of the nozzle 5. The substrate with a wet film is placed on the spin coater 6. The center of the nozzle 5 outlet is directly opposite to the center of the wet film. The distance between the nozzle 5 outlet and the wet film is 0.5 to 1.5 cm. The atomized gas ejected from the nozzle 5 outlet forms a cone. The pressure of the atomized gas ejected from the nozzle 5 outlet is 0 to 100 psi, thereby covering the wet film. The atomizer 1, antisolvent tube 2, compressed nitrogen tube 3, gas supply tube 4, nozzle 5, and spin coater 6 can all be mounted on a manipulator 7. The atomizer 1, nozzle 5, and spin coater 6 are primarily connected and installed to the front end of the manipulator 7 according to the aforementioned positional relationship. The antisolvent tube 2 and compressed nitrogen tube 3 are connected and installed relative to the atomizer 1, and the gas supply tube 4 is connected and installed relative to the atomizer 1 and nozzle 5. A flow meter can be installed on the gas supply tube 4. The manipulator can be controlled by a PLC. Driven by the manipulator, the preparation equipment can be docked with the operating equipment in the preceding and following process links, allowing the substrate with a wet film to be placed on the spin coater for spin coating and reaction with the antisolvent. After the reaction is complete, it is transferred to the next operating equipment.

[0028] The following steps were used to prepare the Figure 2 The perovskite solar cell structure shown in the figure includes the following steps: cleaning the ITO glass substrate, forming a hole transport layer, forming a perovskite thin film layer, forming an electron layer, and forming a metal electrode layer. Examples 1-3 and Comparative Example 1 only compare the effects of the perovskite thin film preparation method and apparatus of the present invention by using different preparation methods for the perovskite thin film layer.

[0029] Example 1

[0030] The perovskite film is prepared by using the perovskite film preparation method and preparation equipment of the present invention.

[0031] In step S20, the spin coater first spins at a low speed and then at a high speed. The low-speed spin coating is performed at an acceleration of 250 rpm / s, a rotation speed of 2000 rpm, and a spin coating time of 15 seconds. The high-speed spin coating is performed at an acceleration of 250 rpm / s, increasing the rotation speed from 2000 rpm to 5000 rpm, and a spin coating time of 20 seconds. Antisolvent atomizing gas is continuously introduced starting from the fifth second before the high-speed spin coating, and the atomizing gas reacts with the wet film for 5 seconds. The antisolvent is toluene, the atomizing gas flow rate is 5 ml / min, and the atomizing gas pressure at the nozzle outlet is 30 psi.

[0032] In step S30, the annealing temperature is 110° C. and the annealing time is 20 minutes.

[0033] Example 2

[0034] The method is basically the same as Example 1, except that the gas flow rate of the atomizing gas is 3 ml / min.

[0035] Example 3

[0036] The method is basically the same as Example 1, except that the gas flow rate of the atomizing gas is 1.5 ml / min.

[0037] Comparative Example 1

[0038] The perovskite thin films were prepared by spin coating.

[0039] Step S10: spreading the perovskite precursor solution on the substrate surface to form a wet film;

[0040] Step S20: The antisolvent is toluene, and the substrate is first spin-coated at a low speed and then at a high speed using a step-by-step spin coating method. The low-speed spin coating method includes: an acceleration of 250 rpm / s, a spin coating speed of 2000 rpm, and a spin coating time of 15 s. The high-speed spin coating method includes: an acceleration of 2500 rpm / s, increasing the spin coating speed from 2000 rpm to 5000 rpm, and a spin coating time of 20 s. The antisolvent is added dropwise starting from the 5th second before the high-speed spin coating, and a total of 250 μl of antisolvent is added dropwise over 5 s.

[0041] Step S30: annealing the substrate obtained in step S20 to form a perovskite film, with the annealing temperature being 110° C. and the annealing time being 20 min.

[0042] The perovskite thin films obtained in Examples 1 to 3 and Comparative Example 1 were subjected to SEM testing. The results are shown in the attached figure. Figure 3 As shown, it can be seen that different anti-solvent addition methods affect the crystallization of the perovskite thin film layer. The perovskite grain size of the sample in Comparative Example 1 is larger in the center area and smaller in the edge grain size, while the grain size difference between the center and the edge of the samples of Examples 1 to 3 becomes smaller, and the grain size distribution of the sample in Example 2 is uniform, and there are almost no defects such as pinholes and cracks.

[0043] The electrical performance of the perovskite solar cells prepared using Examples 1 to 3 and Comparative Example 1 was tested, and the results are shown in the attached figure. Figure 4 As shown, it can be seen that the intra-sheet uniformity of the samples of Examples 1 to 3 is significantly improved.

[0044] The perovskite film preparation method and preparation equipment of the present invention use an atomization method to add an anti-solvent to the wet film, thereby suppressing and reducing the uneven gradient distribution of the anti-solvent in the radial direction of the wet film, and improving the uniformity of perovskite grain nucleation. Therefore, perovskite films with uniform distribution of microstructure and photoelectric properties can be better prepared, and efficient perovskite solar cells can be obtained. Actual tests and production have proven that they have high repeatability and process reliability, and improve the uniformity, repeatability and process reliability of perovskite solar cells over a larger area.

Claims

1. A method for improving the uniformity of a perovskite film, characterized in that: The following steps are involved: Step S10: spreading the perovskite precursor solution on the substrate; Step S20: placing the substrate with the wet film on a spin coater for spin coating, adding the antisolvent in the form of atomized gas, covering the wet film and fully contacting and reacting with it; Step S30: annealing the substrate to form a perovskite film.

2. The method for improving the uniformity of a perovskite thin film according to claim 1, wherein: The gas flow rate of the antisolvent atomizing gas is 1 to 15 ml / min, and the reaction time is no more than 10 s.

3. The method for improving the uniformity of a perovskite thin film according to claim 1, wherein: The anti-solvent is one of chlorobenzene, anisole, and toluene.

4. The method for improving the uniformity of a perovskite thin film according to claim 1 or 2, wherein: The spin coating is performed at a low speed first and then at a high speed. The rotation speed of the low speed spin coating is 500-2000 rpm, the acceleration is 100-300 rpm / s, and the time is 5-15 s. The rotation speed of the high speed spin coating is 4000-5500 rpm, the acceleration is 100-300 rpm / s, and the time is 10-30 s. When the countdown of the entire spin coating process does not exceed 10 s, the anti-solvent atomizing gas is introduced to fully contact and react with the wet film.

5. The method for improving the uniformity of a perovskite thin film according to claim 1, wherein: The annealing temperature is 100-130° C., and the annealing time is 10-30 minutes.

6. A preparation device for implementing the preparation method for improving the uniformity of a perovskite thin film according to any one of claims 1 to 5, characterized in that: The preparation equipment of step S20 includes an atomizer (1), an antisolvent tube (2), a compressed nitrogen tube (3), an air supply tube (4), a nozzle (5), and a spin coater (6). The antisolvent tube (2) and the compressed nitrogen tube (3) are respectively connected to the atomizer (1). One end of the air supply tube (4) is connected to the atomizer (1), and the other end of the air supply tube (4) is connected to the inlet of the nozzle (5). The spin coater (6) is located below the outlet of the nozzle (5). The substrate with the wet film is placed on the spin coater (6), and the atomized gas formed at the outlet of the nozzle (5) covers the wet film.

7. The preparation equipment according to claim 6, characterized in that: The preparation equipment further comprises a manipulator (7), and the atomizer (1), the nozzle (5), and the spin coater (6) are all connected and installed to the front end of the manipulator (7).

8. The preparation equipment according to claim 6, characterized in that: The center of the nozzle (5) is aligned with the center of the wet film, the distance between the nozzle (5) outlet and the wet film is 0.5 to 1.5 cm, and the pressure of the atomizing gas ejected from the nozzle (5) outlet is 0 to 100 psi.

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