Perovskite battery based on lithium fluoride passivation layer and preparation method thereof

Abstract

The invention belongs to the technical field of perovskite batteries, and discloses a perovskite battery based on a lithium fluoride passivation layer and a preparation method thereof, and the method comprises the following steps: 1, sequentially preparing a conductive layer, a hole transport layer and a perovskite absorption layer on a substrate; 2, a lithium fluoride passivation layer is prepared on the top of the perovskite absorption layer through radio frequency magnetron sputtering, the power of the radio frequency magnetron sputtering ranges from 60 W to 80 W, the duration of the radio frequency magnetron sputtering ranges from 30 s to 80 s, and annealing treatment is carried out after the radio frequency magnetron sputtering is completed; and step 3, preparing an electron transport layer and an electrode layer on the top of the lithium fluoride passivation layer. The perovskite cell prepared by the preparation method is high in conversion efficiency and long in service life.

Description

Technical Field

[0001] This invention relates to the field of perovskite battery technology, and in particular to a perovskite battery based on a lithium fluoride passivation layer and its preparation method. Background Technology

[0002] Perovskite solar cells (PSCs), as a novel type of solar cell, offer advantages such as simple fabrication, low cost, high conversion efficiency, and the ability to create flexible modules, and are expected to gradually replace currently commercialized silicon solar cells. In perovskite solar cells, adding a halogen alkali metal passivation layer between the perovskite layer and the electron transport layer can improve conversion efficiency by 1-2%. However, existing halogen alkali metal passivation layers exhibit poor uniformity in large-size perovskite solar cells. Furthermore, they are prone to degradation in humid environments, leading to perovskite cell failure. Therefore, perovskite solar cells generally suffer from poor material stability and rapid device degradation, limiting their wider application. Summary of the Invention

[0003] The purpose of this invention is to address the problems of poor uniformity of halogen alkali metal passivation layer distribution and poor stability of perovskite batteries in the prior art, and to provide a perovskite battery based on a lithium fluoride passivation layer and its preparation method. This invention prepares the lithium fluoride passivation layer by radio frequency magnetron sputtering, and reduces the damage to the perovskite absorber layer lattice caused by radio frequency magnetron sputtering by using pulse power supply, low deposition power, annealing treatment and other methods to ensure good passivation effect and extend the service life of perovskite battery.

[0004] The technical solution adopted to achieve the purpose of this invention is:

[0005] A method for fabricating a perovskite solar cell based on a lithium fluoride passivation layer includes the following steps:

[0006] Step 1: Sequentially fabricate a conductive layer, a hole transport layer, and a perovskite absorber layer on the substrate;

[0007] Step 2: A lithium fluoride passivation layer is prepared on top of the perovskite absorber layer using radio frequency magnetron sputtering. The power of the radio frequency magnetron sputtering is 60~80W and the duration of the radio frequency magnetron sputtering is 30~80s. After the radio frequency magnetron sputtering is completed, an annealing treatment is performed.

[0008] Step 3: Prepare an electron transport layer and an electrode layer on top of the lithium fluoride passivation layer.

[0009] In the above technical solution, in step 1, the area of ​​the substrate is 30cm×30cm or 30cm×40cm, and the material of the substrate is borosilicate glass.

[0010] In the above technical solution, in step 1, the conductive layer is an FTO conductive layer, which is prepared by magnetron sputtering.

[0011] The hole transport layer is NiO. x Hole transport layer, x=1.5~2, is prepared by laser scribing on the surface of FTO conductive layer and then magnetron sputtering on top of FTO conductive layer.

[0012] The perovskite absorber layer is made of Cs. m MA n FA （1-m-n） PbI3 (formamidine lead iodide doped with Cs ions and methylamine (MA) ions), m=0~0.25 and not 0, n=0~0.5 and not 0, the perovskite absorber layer is prepared by slit coating method.

[0013] In the above technical solution, in step 2, the thickness of the lithium fluoride passivation layer is 0.5~2nm.

[0014] In the above technical solution, in step 2, the annealing time is 10~30min and the annealing temperature is 100~150℃.

[0015] In the above technical solution, in step 2, the power pulse frequency of the radio frequency magnetron sputtering is 13.56MHz.

[0016] In the above technical solution, during step 2 of the radio frequency magnetron sputtering process, the substrate obtained in step 1, loaded with a conductive layer, a hole transport layer, and a perovskite absorber layer, is placed in the magnetron sputtering cavity and evacuated. When the cavity vacuum reaches 6.5 × 10⁻⁶... -4 After Pa, the chamber pressure is adjusted to 0.4 Pa and kept stable before radio frequency magnetron sputtering is started.

[0017] In the above technical solution, the argon flow rate is 12-20 sccm.

[0018] In the above technical solution, in step 3, the electron transport layer includes C 60 An electron transport layer and a BCP electron transport layer are provided. The electron transport layer is prepared by vapor deposition. After laser scribing on the top of the BCP electron transport layer, an electrode layer is prepared by vapor deposition. The electrode layer is a silver electrode layer or a copper electrode layer.

[0019] Another aspect of the present invention includes a perovskite solar cell obtained by the preparation method, comprising, from bottom to top, a substrate, a conductive layer, a hole transport layer, a perovskite absorber layer, a lithium fluoride passivation layer, an electron transport layer, and an electrode layer.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention uses radio frequency magnetron sputtering (power pulse frequency 13.56MHz) instead of DC magnetron sputtering; the deposition power is reduced from the commonly used 100W to 60~80W, and the deposition rate is reduced while ensuring the uniformity of the film; and an annealing step is added after radio frequency magnetron sputtering to play a role in lattice repair. The lithium fluoride passivation layer prepared by radio frequency magnetron sputtering has good uniformity and is suitable for the preparation of large-area perovskite solar cells.

[0022] 2. This invention uses radio frequency magnetron sputtering to deposit lithium fluoride. Simultaneously, by employing pulsed power supplies, low deposition power, and post-annealing treatment, it reduces the damage to the perovskite layer lattice caused by radio frequency magnetron sputtering, achieving a good passivation effect. Furthermore, because the lithium fluoride deposited by radio frequency magnetron sputtering has a more uniform morphology and better barrier properties against substances such as water and oxygen in the environment, the perovskite solar cells prepared by this invention have a longer lifespan.

[0023] 3. Compared to other perovskite layer passivation materials such as PEAI (phenylethyl ammonium iodide) and CsI, Li + and F - The two ions are relatively small and, after annealing, reside in the voids of the perovskite lattice structure, thus allowing the perovskite absorber layer to interact with the C... 60 There is less charge accumulation at the interface of the electron transport layer, resulting in better passivation. Therefore, LiF, RF magnetron sputtering, and annealing are all indispensable. The three work together to improve conversion efficiency and extend service life. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the perovskite solar cell in Example 1.

[0025] Figure 2 This is a schematic diagram showing the linear relationship between the reciprocal of the square of the capacitance and the applied potential in Example 2, Comparative Example 1, and Comparative Example 3. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] Example 1

[0028] A method for fabricating a perovskite solar cell based on a lithium fluoride passivation layer includes the following steps:

[0029] Step 1: Clean a 30cm × 30cm borosilicate glass substrate. Prepare an FTO conductive layer on the surface of the borosilicate glass substrate by magnetron sputtering. After laser scribing on the surface of the FTO conductive layer, prepare NiO by magnetron sputtering. xA hole transport layer with x = 1.5~2 was formed, followed by the fabrication of a perovskite absorber layer using a slit coating method. The perovskite absorber layer was made of formamidinium lead iodide (CsO2) doped with Cs ions and methylamine (MA) ions. m MA n FA （1-m-n） PbI3), m=0~0.25 and not 0, n=0~0.5 and not 0, step 1 yields a borosilicate glass substrate loaded with a conductive layer, a hole transport layer and a perovskite absorption layer;

[0030] Step 2, Preparation of lithium fluoride passivation layer by radio frequency magnetron sputtering: The borosilicate glass substrate obtained in Step 1, loaded with the conductive layer, hole transport layer, and perovskite absorber layer, is placed in the magnetron sputtering cavity and evacuated. When the cavity vacuum reaches 6.5 × 10⁻⁶, the vacuum level is increased to 6.5 × 10⁻⁶. -4 After Pa, the power was set to 80W, and the chamber pressure was adjusted to 0.4Pa and kept stable by adjusting the argon flow rate. Radio frequency magnetron sputtering was started, and the radio frequency magnetron sputtering time was 46s to obtain a lithium fluoride passivation layer with a thickness of 1nm. The borosilicate glass substrate loaded with the conductive layer, hole transport layer, perovskite absorption layer and lithium fluoride passivation layer was taken out and placed on a heating stage that had been heated to 100℃ for annealing for 30min.

[0031] Step 3: After annealing, C is prepared on the surface of the lithium fluoride passivation layer by vapor deposition. 60 An electron transport layer and a BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) electron transport layer were prepared, followed by laser scribing and then a silver electrode layer was prepared by vapor deposition. Finally, laser scribing, laser edge cleaning, and encapsulation were performed to obtain a perovskite solar cell.

[0032] Radio frequency magnetron sputtering uses high-energy particles to bombard a lithium fluoride target, generating atomic-level microparticles for deposition. Compared to evaporation, the Li₂... + and F - When the doping depth into the perovskite absorber layer is greater, and because these two ions are smaller in size, after annealing, they are located in the gaps of the perovskite lattice structure, thus allowing the perovskite absorber layer to interact with C. 60 Less charge buildup at the interface of the electron transport layer ultimately passivates the grain boundaries, thereby improving the stability of the perovskite solar cell and extending its lifespan.

[0033] For the perovskite solar cell obtained in this embodiment (e.g.) Figure 1 (As shown) Efficiency and reliability tests were conducted. The lifespan of the perovskite solar cell was characterized by the efficiency change before and after 1000 hours of storage at room temperature. The efficiency test method is as follows:

[0034] The current-voltage (JV) characteristics were recorded by applying an external potential bias to the assembled battery device, while the generated photocurrent was recorded using a digital source meter (Keithley 2400). A 450W xenon lamp equipped with a daylight filter was used as the light source to ensure that the lamp's emission spectrum conformed to the AM 1.5 G standard.

[0035] The results are as follows:

[0036] The average conversion efficiency of the perovskite solar cell obtained in Example 1 was 17.01%, and the efficiency after 1000 hours of storage was 93.53% of that before storage.

[0037] Detailed data can be found in pieces 7 and 8 of Table 1.

[0038] Example 2

[0039] A method for preparing a perovskite solar cell based on a lithium fluoride passivation layer, wherein steps 1 and 3 are the same as in Example 1, except for step 2:

[0040] The borosilicate glass substrate obtained in step 1, loaded with the conductive layer, hole transport layer, and perovskite absorber layer, was placed in a magnetron sputtering cavity and evacuated. When the cavity vacuum reached 6.5 × 10⁻⁶, the vacuum level was increased to 6.5 × 10⁻⁶. -4 After Pa, the power was set to 70W, and the chamber pressure was adjusted to 0.6Pa and kept stable by adjusting the argon flow rate. Radio frequency sputtering was started for 53s to obtain a lithium fluoride passivation layer with a thickness of 1nm. The borosilicate glass substrate loaded with the conductive layer, hole transport layer, perovskite absorption layer and lithium fluoride passivation layer was taken out and placed on a heating stage heated to 125℃ for annealing for 20min.

[0041] The efficiency and reliability of the perovskite solar cell obtained in this embodiment were tested, and the results are as follows:

[0042] The average conversion efficiency of the perovskite solar cell obtained in this embodiment is 17.25%, and the efficiency after 1000 hours of storage is 94.75% of that before storage.

[0043] Detailed data can be found in Table 1, sections 9 and 10.

[0044] Example 3

[0045] A method for preparing a perovskite solar cell based on a lithium fluoride passivation layer, wherein steps 1 and 3 are the same as in Example 1, except for step 2:

[0046] The borosilicate glass substrate obtained in step 1, loaded with the conductive layer, hole transport layer, and perovskite absorber layer, was placed in a magnetron sputtering cavity and evacuated. When the cavity vacuum reached 6.5 × 10⁻⁶, the vacuum level was increased to 6.5 × 10⁻⁶. -4After Pa, the power was set to 60W, and the chamber pressure was adjusted to 0.8Pa and kept stable by adjusting the argon flow rate. Radio frequency sputtering was started for 62s to obtain a lithium fluoride passivation layer with a thickness of 1nm. The borosilicate glass substrate loaded with the conductive layer, hole transport layer, perovskite absorption layer and lithium fluoride passivation layer was taken out and placed on a heating stage heated to 150℃ for annealing for 10min.

[0047] The efficiency and reliability of the perovskite solar cell obtained in this embodiment were tested, and the results are as follows:

[0048] The average conversion efficiency of the perovskite solar cell obtained in this embodiment is 17.23%, and the efficiency after 1000 hours of storage is 91.96% of that before storage.

[0049] Detailed data can be found in Table 1, sections 11 and 12.

[0050] Comparative Example 1

[0051] The lithium fluoride passivation layer in this comparative example was prepared by vapor deposition.

[0052] A method for preparing a perovskite battery based on a lithium fluoride passivation layer by vapor deposition, wherein steps 1 and 3 are the same as in Example 1, except that in step 2, the lithium fluoride passivation layer is prepared by vapor deposition: the lithium fluoride vapor deposition rate is 0.1 A / s, and the thickness of the lithium fluoride passivation layer is 1 nm.

[0053] The efficiency and reliability of the perovskite solar cell obtained in this comparative example were tested, and the results are as follows:

[0054] The average conversion efficiency of the perovskite solar cell obtained in this comparative example was 16.41%, and the efficiency after 1000 hours of storage was 83.81% of that before storage.

[0055] Detailed data can be found in Table 1, Sections 1 and 2.

[0056] Comparative Example 2

[0057] The lithium fluoride passivation layer in this comparative example was not annealed after magnetron sputtering.

[0058] A method for preparing a perovskite solar cell based on a lithium fluoride passivation layer, wherein steps 1 and 3 are the same as in Example 1, except for step 2:

[0059] The borosilicate glass substrate obtained in step 1, loaded with the conductive layer, hole transport layer, and perovskite absorber layer, was placed in a magnetron sputtering cavity and evacuated. When the cavity vacuum reached 6.5 × 10⁻⁶, the vacuum level was increased to 6.5 × 10⁻⁶. -4 After Pa, the power was set to 80W, and the chamber pressure was adjusted to 0.4Pa and maintained stable by adjusting the argon gas flow rate. Radio frequency sputtering was then initiated for 46s to obtain a 1nm thick lithium fluoride passivation layer. No annealing step was performed.

[0060] The efficiency and reliability of the perovskite solar cell obtained in this comparative example were tested, and the results are as follows:

[0061] The average conversion efficiency of the perovskite solar cell obtained in this comparative example was 16.64%, and the efficiency was 86.30% of that before placement after 1000 hours.

[0062] Detailed data can be found in pieces 3 and 4 of Table 1.

[0063] Comparative Example 3

[0064] In this comparative example, the passivation layer is replaced with cesium iodide (CsI), replacing lithium fluoride.

[0065] A method for fabricating a perovskite solar cell based on a cesium iodide passivation layer by magnetron sputtering, wherein steps 1 and 3 are the same as in Example 1, except for step 2:

[0066] The borosilicate glass substrate obtained in step 1, loaded with the conductive layer, hole transport layer, and perovskite absorber layer, was placed in a magnetron sputtering cavity and evacuated. When the cavity vacuum reached 6.5 × 10⁻⁶, the vacuum level was increased to 6.5 × 10⁻⁶. -4 After Pa, the power was set to 80W, and the chamber pressure was adjusted to 0.4Pa and kept stable. Radio frequency sputtering was then performed for 46s to obtain the cesium iodide passivation layer. The borosilicate glass substrate loaded with the conductive layer, hole transport layer, perovskite absorber layer, and cesium iodide passivation layer was removed and placed on a heating stage heated to 100℃ for annealing for 30min.

[0067] The efficiency and reliability of the perovskite solar cell obtained in this comparative example were tested, and the results are as follows: the average conversion efficiency was 16.89%, and the efficiency after 1000 hours of storage was 86.61% of that before storage.

[0068] Detailed data can be found in pieces 5 and 6 of Table 1.

[0069] Using the Mott-Schottky equation to study the perovskite absorber layer and C 60 The amount of charge accumulation between electron transport layers is characterized. The Mott-Schottky equation is as follows:

[0070]

[0071] Where C is the interface capacitance; ε is the relative permittivity, which depends only on the material type; ε0 is the absolute permittivity; N D V is the carrier concentration at the interface; V is the applied potential; V FB It is a flat band potential; k B T / e is a constant. This shows that the reciprocal of the square of the capacitance has a linear relationship with the applied potential. The slope and intercept of this linear relationship can be used to calculate the carrier concentration and determine the flat-band potential, respectively.

[0072] Use 1 / C 2 Plotting V as the ordinate and V as the abscissa, the slope of the linear portion of the graph is 2 / The larger the absolute value of the slope, the smaller the carrier concentration at the interface, indicating that the perovskite absorber layer and C 60 There is less charge buildup between electron transport layers.

[0073] Therefore, Example 2, Comparative Example 1, and Comparative Example 3 were verified, and the results are as follows: Figure 2 As shown, the absolute value of the curve slope of Example 2 is 5.82, which is higher than that of the comparative example. The absolute value of the curve slope of Comparative Example 1 is 4.47, and the absolute value of the curve slope of Comparative Example 3 is 5.09. Therefore, the surface charge density of Example 2 is lower than that of Comparative Example 1 and Comparative Example 3.

[0074] Table 1 Performance Tests

[0075] ;

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the preparation of a perovskite cell based on a lithium fluoride passivation layer, characterized in that, The method comprises the following steps: Step 1, sequentially preparing a conductive layer, a hole transport layer and a perovskite absorption layer on a substrate; Step 2, preparing a lithium fluoride passivation layer on the top of the perovskite absorption layer by radio frequency magnetron sputtering, the power of the radio frequency magnetron sputtering is 60-80 W, the time of the radio frequency magnetron sputtering is 30-80 s, and annealing treatment is performed after the radio frequency magnetron sputtering is completed; Step 3, preparing an electron transport layer and an electrode layer on the top of the lithium fluoride passivation layer.

2. The production method according to claim 1, wherein In the step 1, the area of the substrate is 30 cm*30 cm or 30 cm*40 cm, and the material of the substrate is borosilicate glass.

3. The production method according to claim 1, wherein In the step 1, the conductive layer is an FTO conductive layer, which is prepared by a magnetron sputtering method. The hole transport layer is NiO x The hole transport layer is prepared on the top of the FTO conductive layer by magnetron sputtering after laser scribing on the surface of the FTO conductive layer The material of the perovskite absorption layer is Cs m MA n FA （1-m-n） PbI3, m=0~0.25 and not 0, n=0~0.5 and not 0, and the perovskite absorption layer is prepared by a slot coating method.

4. The production method according to claim 1, wherein In the step 2, the thickness of the lithium fluoride passivation layer is 0.5-2 nm.

5. The production method according to claim 1, wherein In the step 2, the annealing time is 10-30 min, and the annealing temperature is 100-150 DEG C.

6. The production method according to claim 1, wherein In the step 2, the power supply pulse frequency of the radio frequency magnetron sputtering is 13.56 MHz.

7. The production method according to claim 1, wherein In step 2, the substrate loaded with the conductive layer, the hole transport layer and the perovskite absorption layer obtained in step 1 is placed in a magnetron sputtering cavity for vacuum pumping. When the cavity vacuum degree reaches 6.5×10 -4 After the cavity vacuum degree reaches 6.5×10 Pa, the cavity pressure is adjusted to 0.4 Pa by adjusting the argon flow rate, and the radio frequency magnetron sputtering is started.

8. The production method according to claim 7, wherein The argon flow rate is 12-20 sccm.

9. The production method according to claim 1, wherein In step 3, the electron transport layer includes C 60 The electron transport layer is prepared by evaporation method, and the electrode layer is prepared by evaporation method after laser scribing on the top of the BCP electron transport layer. The electrode layer is a silver electrode layer or a copper electrode layer.

10. The perovskite cell obtained by the production method according to any one of claims 1 to 9, characterized by, From bottom to top, the substrate, the conductive layer, the hole transport layer, the perovskite absorption layer, the lithium fluoride passivation layer, the electron transport layer and the electrode layer are sequentially prepared.

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