Method for improving stability of sol in industrialized perovskite solar cell

Abstract

The invention discloses a method for improving the stability of sol in an industrial perovskite solar cell, perovskite precursor sol is cryopreserved at low temperature, volatilization of a solvent and aggregation of the sol are prevented, when the sol needs to be used, the cryopreserved sol can recover the sol state, no additional processing step is needed, and the stability of the sol in the industrial perovskite solar cell is improved. The perovskite thin film is prepared by using the sol subjected to cryopreservation, so that a thin film structure with relatively low defect state density is obtained, and a uniform and stable alpha-FAPbI3 phase is formed. According to the method for improving the stability of the sol in the industrial perovskite solar cell, the sol state can be conveniently recovered through the frozen and preserved sol, additional processing steps are not needed, the perovskite thin film is prepared through the frozen and preserved sol, a thin film structure with low defect state density can be obtained, and the stability of the sol in the industrial perovskite solar cell is improved. And a uniform and stable alpha-FAPbI3 phase is formed, so that the photoelectric conversion efficiency and the stability of the perovskite module are improved.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a method for improving the stability of sol in industrialized perovskite solar cells. Background Art

[0002] Since the first appearance of perovskite solar cells in 2009, the photoelectric conversion efficiency of organic-inorganic hybrid perovskite solar cells has reached 26.7%. Its relatively low cost, excellent photoelectric conversion performance and other advantages provide a new path to solve energy problems around the world. In the industrialization process of perovskite solar cells, a key issue has gradually emerged - the stability of the perovskite precursor sol. High sol stability can ensure the uniform spreading of the perovskite precursor solution during the coating process, thereby reducing holes and cracks in the film, which is crucial to improving the photoelectric conversion efficiency of the battery; good sol stability can also help improve the reproducibility of large-area perovskite film preparation, thereby speeding up production and reducing production interruptions and material waste caused by unstable sols, which is of great significance for industrial production.

[0003] During the storage of the sol, due to the influence of factors such as solvent selection, temperature, water, oxygen, and light, a series of changes occur inside the perovskite precursor sol, such as changes in the colloidal particle structure caused by solvent-solute coordination, oxidation of I- ions, or chemical reactions involving organic amine cations [formamide (FA+) and methylammonium (MA+)] or solvents [mainly N,N-dimethylformamide (DMF)], which cause the perovskite precursor sol to age and deteriorate, which is very unfavorable for the industrialization of perovskite solar cells. Therefore, it is necessary to develop a simple and stable sol storage method for large-scale preparation of perovskite solar cells. Summary of the invention

[0004] The invention discloses a method for improving the stability of sol in industrialized perovskite solar cells, aiming to solve the technical problems raised in the background technology.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for improving the stability of sol in industrialized perovskite solar cells, specifically comprising the following steps:

[0007] Step 1: Setting a hole transport layer film;

[0008] Step 2: Setting the perovskite light absorbing layer;

[0009] Step 3: Setting up an electron transport layer;

[0010] Step 4: Setting the back electrode layer;

[0011] In the step 2, the perovskite precursor sol is frozen and stored at low temperature to prevent the volatilization of the solvent and the aggregation of the sol. When needed, the frozen sol can be restored to its sol state without the need for additional processing steps. By using the frozen sol to prepare a perovskite film, a film structure with a lower defect state density is obtained, and a uniform and stable α-FAPbI3 phase is formed.

[0012] In a preferred embodiment, the step 1 includes the following three steps:

[0013] S1.1: Prepare the solar cell substrate: Use laser to etch the pattern of the transparent conductive glass substrate (FTO / glass). After the etching is completed, use detergent, deionized water, ethanol, isopropanol to clean and ultrasonically treat it in sequence, and then dry it for use;

[0014] S1.2: Use magnetron sputtering to sputter NiOx onto the etched conductive substrate. The sputtering conditions are: Ni palladium, DC power supply 200W, 20min, carrier gas flow rate Ar:O2=200:30 (sccm);

[0015] S1.3: Use programmed temperature rise, heat from 150℃ to 300℃ and then anneal for 20min.

[0016] In a preferred embodiment, the step 2 specifically includes the following three steps:

[0017] S2.1: PbI2, FAI, MACl, CsI are dissolved in DMF:NMP:2-Me=12:1:1 (volume

[0018] The precursor solution was placed in a -25°C incubator for 24 hours.

[0019] S2.2: Slit coating method: The perovskite precursor solution is coated on the substrate with the sputtered hole transport layer, as follows: pre-injection volume 50μl, pre-injection speed 15μl / s, coating speed 10cm / s, injection speed 3μl / s, waiting time 3s;

[0020] S3.3: After the coating is completed, the wet perovskite film is immediately transferred to the vacuum crystallization equipment. Under the condition of 25kPa, the crystallization is carried out for 1 minute. After being taken out, it is placed on a hot plate at 150°C for 15 minutes to obtain the perovskite film.

[0021] In a preferred embodiment, in step three, C60 and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) are deposited on the above-prepared film by thermal evaporation, with thicknesses of 18 nm and 3 nm, respectively.

[0022] In a preferred embodiment, in step 4, a 200 nm copper electrode is vacuum evaporated onto the structure with the electron transport layer by using a vacuum device to obtain a complete battery.

[0023] From the above, it can be seen that a method for improving the stability of sol in industrialized perovskite solar cells specifically includes the following steps: step one: setting a hole transport layer film; step two: setting a perovskite light absorption layer; step three: setting an electron transport layer; step four: setting a back electrode layer; in the step two, the perovskite precursor sol is frozen and stored at low temperature to prevent the volatilization of the solvent and the aggregation of the sol. When it is needed, the frozen sol can be restored to its sol state without additional processing steps, and a perovskite film is prepared by using the frozen sol to obtain a film structure with a lower defect state density, and a uniform and stable α-FAPbI3 phase is formed. The method for improving the stability of sol in industrialized perovskite solar cells provided by the present invention can effectively prevent the volatilization of the solvent and the aggregation of the sol by freezing the perovskite precursor sol at low temperature, thereby maintaining the stability and consistency of the sol. When it is needed, the frozen sol can be easily restored to its sol state without additional processing steps. By using frozen sol to prepare perovskite film, a film structure with low defect state density can be obtained, and a uniform and stable α-FAPbI3 phase can be formed, thereby improving the photoelectric conversion efficiency and stability of the perovskite module. At the same time, the freezing treatment can greatly improve the shelf life of the perovskite precursor sol, which is of great significance for the industrialization of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a SEM result image of the surface of a fresh sol perovskite film proposed in the present invention to improve the sol stability in industrialized perovskite solar cells.

[0025] Figure 2 This is a SEM result image of the surface of an aged sol perovskite film proposed in the present invention to improve the stability of the sol in an industrialized perovskite solar cell.

[0026] Figure 3 This is a SEM result of the perovskite film surface after the sol was frozen and stored for 4 weeks in a method for improving the sol stability in industrialized perovskite solar cells proposed by the present invention.

[0027] Figure 4This is a long-term stability statistical result diagram of a method proposed in the present invention for improving the stability of sol in industrialized perovskite solar cells.

[0028] Figure 5 A diagram of the photoelectric conversion efficiency of a titanite solar cell according to a method proposed by the present invention for improving the stability of the sol in an industrialized perovskite solar cell. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] The frozen perovskite precursor sol used in the embodiments of the present invention can be used for small-area and industrial large-area perovskite solar cells, and is suitable for rigid cells or flexible cells.

[0031] Reference Figure 1-4 , a method for improving the stability of sol in industrialized perovskite solar cells. By freezing the perovskite precursor sol at low temperature, the volatilization of the solvent and the aggregation of the sol can be effectively prevented, thereby maintaining the stability and consistency of the sol. When needed, the frozen sol can be easily restored to its sol state without additional processing steps. By using the frozen sol to prepare the perovskite film, a film structure with a low defect state density can be obtained, and a uniform and stable α-FAPbI3 phase can be formed, thereby improving the photoelectric conversion efficiency and stability of the perovskite module. At the same time, the freezing treatment can greatly improve the shelf life of the perovskite precursor sol.

[0032] In a preferred embodiment, the perovskite solar cell prepared from the precursor sol frozen at -25°C:

[0033] (1) Setting up a hole transport layer film

[0034] a. Prepare the solar cell substrate: Use laser to etch the pattern of the transparent conductive glass substrate (FTO / glass). After etching, use detergent, deionized water, ethanol, isopropanol to clean and ultrasonically treat in sequence, and then dry for use.

[0035] b. Use magnetron sputtering to sputter NiOx onto the etched conductive substrate. The sputtering conditions are: Ni palladium, DC power supply 200W, 20min, carrier gas flow rate

[0036] Ar:O2=200:30 (sccm).

[0037] c. Use programmed temperature rise, heat from 150°C to 300°C, then anneal for 20 minutes.

[0038] (2) Setting up a perovskite light-absorbing layer

[0039] a. Dissolve PbI2, FAI, MACl and CsI in a solvent of DMF:NMP:2-Me=12:1:1 (volume ratio) to obtain a 1M lead iodide precursor solution, and store the precursor solution in a -25°C thermostat for 24 hours.

[0040] b. Use slit coating method

[0041] The perovskite precursor solution is coated on the substrate with the sputtered hole transport layer as follows: pre-injection volume 50 μl, pre-injection speed 15 μl / s, coating speed 10 cm / s, injection speed 3 μl / s, and waiting time 3 s.

[0042] c. After the coating is completed, the perovskite wet film is immediately transferred to the vacuum crystallization equipment and crystallized for 1 minute under 25kPa conditions.

[0043] After taking it out, place it on a hot plate at 150°C for 15 minutes to obtain a perovskite film.

[0044] (3) Setting up electron transport layer

[0045] C60 and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) were deposited on the above-prepared film by thermal evaporation, with thicknesses of 18 nm and 3 nm, respectively.

[0046] (4) Setting the back electrode layer

[0047] Use vacuum equipment to vacuum evaporate a 200nm copper electrode onto the structure with the electron transport layer completed to obtain a complete battery.

[0048] Perovskite solar cells at AM1.5, 100mW / cm 2 The photoelectric performance of the battery was tested using Keithley2400 under light, and the statistical results are shown in Table 1.

[0049] After the test, the battery was subjected to long-term stability test. The changes in the photoelectric conversion efficiency after storage for different lengths of time in the atmospheric environment are shown in Table 2 and Figure 4 .

[0050] The statistical results of the photoelectric conversion efficiency of perovskite solar cells prepared by storing the perovskite precursor sol in a -25°C constant temperature box for 0 weeks, 1 week, 2 weeks, 3 weeks, and 4 weeks are shown in Tables 3 and Figure 5 .

[0051] Comparative Examples 1 and 2: Perovskite solar cells prepared from precursor sols stored at 25°C and 50°C:

[0052] The preparation method and the test method of Example 1 are basically the same, except that in step (2)a, the perovskite precursor sol is placed in a constant temperature box at 25°C and 50°C for 24 hours, respectively, as Comparative Examples 1 and 2.

[0053] The statistical results of the cell photoelectric conversion efficiency and long-term stability are shown in Table 1, Table 2 and Figure 4 .

[0054] The statistical results of the photoelectric conversion efficiency of perovskite solar cells prepared by storing the perovskite precursor sol in a constant temperature box at 25°C and 50°C for 0 week, 1 week, 2 weeks, 3 weeks, and 4 weeks are shown in Tables 3 and Figure 5 .

[0055] The present invention stores the precursor sol in a constant temperature box at -25°C, thereby improving the stability of the sol and reducing the defect density on the surface of the perovskite film, thereby ultimately improving the performance of the perovskite solar cell. Figure 1-2 As shown, the SEM results of the perovskite film surface after the sol in the embodiment was frozen and stored for 4 weeks are as follows Figure 3 As shown, it can be seen that a large amount of PbI2 impurities are precipitated on the surface of the perovskite film after sol aging, while there is no obvious precipitation of PbI2 impurities on the surface of the film prepared by the sol that has been frozen for one month, and the grains are slightly enlarged, which reflects better crystallinity. The efficiency test results show that the photoelectric conversion efficiency of the perovskite solar cell after freezing the precursor sol is increased to 22.0%, which is 2.5% higher than the device with the sol stored at 25°C, and 6.6% higher than the device with the sol stored at 50°C; based on the sol preservation strategy of the present invention, the long-term stability of the embodiment, comparative example 1 and comparative example 2 was tested, and the photoelectric conversion efficiency of the device was tested on the day, second week, fourth week and sixth week after the device was prepared. The results show that after 6 weeks, the photoelectric conversion efficiency of the embodiment device can still maintain 95% of the original efficiency, while the device with the sol stored at 25°C drops to 85% of the original efficiency, and the device with the sol stored at 50°C drops to 1.5%. The efficiency of the device is reduced to 75% of the original efficiency; the long-term stability of the sols of the embodiment, comparative example 1 and comparative example 2 is tested, and the photoelectric conversion efficiency of the device after the sol is stored for 0 weeks, 1 week, 2 weeks, 3 weeks and 4 weeks under three conditions is tested respectively. The results show that after 4 weeks, the photoelectric conversion efficiency of the device made of the sol of the embodiment can still maintain 99% of the original efficiency, while the efficiency of the device stored at 25°C is reduced to 42% of the original efficiency, and the efficiency of the device stored at 50°C is reduced to 43% of the original efficiency; the above results show that the method of the present invention can reduce the defect density of the perovskite film, improve the device performance, and significantly improve the stability of the precursor sol. In addition, the method is simple to operate and is of great significance for the industrial application of perovskite solar cells.

[0056]

[0057] Table 1

[0058] Placement time 0 Weeks 2 weeks 4 weeks 6 weeks Example 22.0％ 21.5％ 21.2％ 20.8％ Comparative Example 1 19.5％ 18.8％ 18.0％ 16.5％ Comparative Example 2 15.4％ 14.2％ 13.0％ 11.5％

[0059] Table 2

[0060]

[0061] Table 3

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for improving the stability of sol in industrialized perovskite solar cells, It is characterized in that The specific steps include: Step 1: Setting a hole transport layer film; Step 2: Setting the perovskite light absorbing layer; Step 3: Setting up an electron transport layer; Step 4: Setting the back electrode layer; In the step 2, the perovskite precursor sol is frozen and stored at low temperature to prevent the volatilization of the solvent and the aggregation of the sol. When needed, the frozen sol can be restored to its sol state without the need for additional processing steps. By using the frozen sol to prepare a perovskite film, a film structure with a lower defect state density is obtained, and a uniform and stable α-FAPbI3 phase is formed.

2. A method for improving the stability of sol in industrialized perovskite solar cells according to claim 1, It is characterized in that The step 1 includes the following three steps: S1.1: Prepare the solar cell substrate: Use laser to etch the pattern of the transparent conductive glass substrate (FTO / glass). After the etching is completed, use detergent, deionized water, ethanol, isopropanol to clean and ultrasonically treat it in sequence, and then dry it for use; S1.2: Use magnetron sputtering to sputter NiOx onto the etched conductive substrate. The sputtering conditions are: Ni palladium, DC power supply 200W, 20min, carrier gas flow rate Ar:O 2 =200:30(sccm); S1.3: Use programmed temperature rise, heat from 150℃ to 300℃ and then anneal for 20min.

3. A method for improving the stability of sol in industrialized perovskite solar cells according to claim 1, It is characterized in that The step 2 specifically includes the following three steps: S2.1: PbI 2 , FAI, MACl, CsI were dissolved in DMF:NMP:2-Me=12:1:1 (volume The precursor solution was placed in a -25°C incubator for 24 hours. S2.2: Slit coating method: The perovskite precursor solution is coated on the substrate with the sputtered hole transport layer, as follows: pre-injection volume 50μl, pre-injection speed 15μl / s, coating speed 10cm / s, injection speed 3μl / s, waiting time 3s; S3.3: After the coating is completed, the wet perovskite film is immediately transferred to the vacuum crystallization equipment. Under the condition of 25kPa, the crystallization is carried out for 1 minute. After being taken out, it is placed on a hot plate at 150°C for 15 minutes to obtain the perovskite film.

4. A method for improving the stability of sol in industrialized perovskite solar cells according to claim 1, It is characterized in that In the step three, C60 and 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) are respectively deposited on the above-prepared film by thermal evaporation, with thicknesses of 18 nm and 3 nm, respectively.

5. A method for improving the stability of sol in industrialized perovskite solar cells according to claim 1, It is characterized in that In the step 4, a 200 nm copper electrode is vacuum evaporated onto the structure where the electron transport layer is completed using a vacuum device to obtain a complete battery.

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