A trifluoroborate doped organic-inorganic hybrid perovskite solar cell and a preparation method thereof

Abstract

The application discloses a trifluoroborate doped organic-inorganic hybrid perovskite solar cell, which comprises, from bottom to top, a conductive substrate, a hole transport layer, a perovskite light absorption layer, an electron transport layer and an electrode layer, wherein the perovskite light absorption layer is doped with trifluoroborate, and the structure of the trifluoroborate is shown in the following. The application further discloses a preparation method of the trifluoroborate doped organic-inorganic hybrid perovskite solar cell. The application improves the quality of the prepared perovskite thin film by doping trifluoroborate in a perovskite precursor solution, so that a perovskite solar cell with excellent photoelectric performance and stability is further prepared. The application has the advantages of simple preparation process, low cost and contribution to commercialization of the perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell fabrication technology, specifically to a method for fabricating a trifluoroborate-doped organic-inorganic hybrid perovskite solar cell. Background Technology

[0002] The demand for photovoltaics is experiencing explosive growth, and its share of primary energy consumption is expected to rise from less than 1% to over 25% in the future, indicating a promising future for the photovoltaic market. Perovskite solar cells, as a third-generation type of solar cell, have achieved a laboratory-certified efficiency of 26.1% for their single-junction cells (comparable to crystalline silicon solar cells). Perovskite solar cells have advantages in fabrication processes and manufacturing costs, and are expected to replace crystalline silicon cells in the future, triggering a new round of technological revolution in the photovoltaic industry.

[0003] However, the commercialization of perovskite solar cells is still limited by the long-term stability of the devices. Typically, exposure to external environments (such as humidity, light, oxygen, and temperature) causes rapid degradation in perovskite solar cells. While degradation caused by humidity and oxygen can be avoided through advanced encapsulation technologies, degradation caused by light and temperature is related to point defects formed at perovskite grain boundaries and interfaces within the solar cell. Therefore, eliminating the inherent instability of perovskite caused by light and temperature is crucial for improving the performance and stability of perovskite solar cells.

[0004] Using passivating agents to reduce defects in perovskite materials has proven to be an effective method for improving the photoelectric performance and long-term stability of perovskite solar cells. Adding suitable additives to the perovskite precursor solution can effectively passivate defects and improve the quality of the perovskite film through interactions between the additive molecules and the perovskite components. Simultaneously, it synergistically improves the energy level matching between the perovskite layer and the charge transport layer, enhancing carrier extraction and transport capabilities. This is of great significance for improving the photoelectric performance and stability of perovskite solar cells and advancing their commercialization.

[0005] Patent document CN114551727A discloses a perovskite solar cell based on dual doping of o-dichlorobenzene and 2-mercaptopyridine and its fabrication method. The solar cell employs a nip positive structure of ITO / SnO2 / Perovskite / SpiroOMeTAD / Ag, where Perovskite is the perovskite layer co-doped with o-dichlorobenzene and 2-mercaptopyridine. The introduction of o-dichlorobenzene and 2-mercaptopyridine effectively passivates the uncoordinated Pb in the perovskite layer. 2+ The defects were reduced, thus decreasing the nonradiative recombination loss of photogenerated carriers; at the same time, the grain size was increased, grain boundaries were reduced, and the crystallinity of the perovskite layer was improved.

[0006] Patent document CN111540830B discloses a doped perovskite solar cell and its fabrication method. This doped perovskite solar cell device includes a cathode substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an anode electrode. The perovskite light-absorbing layer is composed of dopamine-doped MAPbI3. The phenolic hydroxyl group on the dopamine benzene ring is easily oxidized to a carbonyl group, and the lone pair electrons on the oxygen atom in the carbonyl group can pair with the empty orbitals of the Pb atoms in MAPbI3 to form bonds. The addition of dopamine effectively improves the crystallinity of MAPbI3, reduces grain boundaries and internal defects, extends carrier lifetime, and reduces carrier recombination, ultimately improving the photoelectric conversion efficiency of the doped perovskite solar cell.

[0007] The aforementioned perovskite thin film fabrication processes all utilize additives to modify the perovskite active layer, thereby improving the quality of the perovskite thin film. However, these additives primarily focus on controlling the crystallization and passivating defects in the perovskite thin film. Therefore, finding a fabrication method for perovskite solar cells that can simultaneously control crystallization, improve morphology, passivate defects, and enhance the photoelectric performance and operational stability of the device remains a significant challenge. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a trifluoroborate-doped organic-inorganic hybrid perovskite solar cell. The perovskite light-absorbing layer of this solar cell contains trifluoroborate, which can improve the quality of the perovskite thin film, thereby enabling the perovskite solar cell to have excellent photoelectric performance and stability.

[0009] A trifluoroborate-doped organic-inorganic hybrid perovskite solar cell includes, from bottom to top, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode layer, wherein the perovskite light-absorbing layer is doped with trifluoroborate.

[0010] The perovskite light-absorbing layer of the organic-inorganic hybrid perovskite solar cell of the present invention contains trifluoroborate, wherein the trifluoroborate contains -BF3 - N atoms, O atoms and uncoordinated Pb in the perovskite light-absorbing layer 2+ Furthermore, strong coordination interactions arise from halide vacancies, with cations in trifluoroborate interacting with uncoordinated I atoms. - / Br -Furthermore, the strong coordination effect generated by cation vacancies can effectively improve the crystallinity and internal defects of perovskite. Simultaneously, trifluoroborate can adjust the energy level matching between the perovskite layer and the charge transport layers (including electron and hole transport layers), enhancing carrier extraction and transport capabilities and reducing residual stress in the perovskite layer. In addition, the hydrogen bonding between the F atoms in trifluoroborate and the perovskite effectively improves the intrinsic stability of the perovskite material, thereby further enhancing the photoelectric performance and stability of perovskite solar cells.

[0011] Preferably, the structural formula of the trifluoroborate is:

[0012]

[0013] Wherein, n is an integer from 1 to 10, R is -CH3, -CH(CH3)2 or -C(CH3)3, and M is Li, Na, K, Rb or Cs.

[0014] Preferably, the conductive substrate is FTO or ITO.

[0015] Preferably, the hole transport layer material is MeO-2PACz.

[0016] Preferably, the perovskite light-absorbing layer material is FAPbI3, MAPbBr3, or CsPb(I x Br 1-x )3, where 0 < x < 1 or one of them.

[0017] Preferably, the electron transport layer material is PC. 61 BM.

[0018] Preferably, the electrode layer material is Ag, and the thickness is 80~120 nm.

[0019] Preferably, the perovskite solar cell further includes an electron transport modification layer located between the electron transport layer and the electrode layer.

[0020] Preferably, the electron transport modification layer material is BCP.

[0021] The present invention also provides a method for preparing the above-mentioned organic-inorganic hybrid perovskite solar cell. The method uses a perovskite precursor solution doped with trifluoroborate to prepare a perovskite light-absorbing layer. The prepared solar cell has high stability and photoelectric conversion efficiency. Moreover, the method is simple and low in cost, which is conducive to the commercialization of perovskite solar cells.

[0022] A method for preparing the above-mentioned organic-inorganic hybrid perovskite solar cell includes the following steps:

[0023] (1) A hole transport material is spin-coated onto a conductive substrate and annealed to obtain a hole transport layer;

[0024] (2) Coat the hole transport layer obtained in step (1) with a trifluoroborate-doped perovskite precursor solution, anneal, and obtain a perovskite light-absorbing layer.

[0025] (3) Coat the perovskite light-absorbing layer obtained in step (2) with an electron transport material, and anneal it to obtain an electron transport layer;

[0026] (4) Electrode material is deposited on the electron transport layer obtained in step (3) to obtain the organic-inorganic hybrid perovskite solar cell.

[0027] Preferably, in step (1), the hole transport material is an ethanol solution of MeO-2PACz, and the concentration of the ethanol solution of MeO-2PACz is 0.1~1 mg / ml.

[0028] Preferably, in step (1), the annealing temperature is 100~150 ℃ and the time is 5~10 min.

[0029] Preferably, in step (2), the preparation method of the trifluoroborate-doped perovskite precursor solution is as follows: trifluoroborate is added to the perovskite precursor solution and heated and stirred.

[0030] Preferably, the heating temperature is 25~70 ℃ and the stirring time is 15~60 min.

[0031] Preferably, in step (2), the perovskite precursor solution comprises a perovskite material and a precursor solvent, wherein the perovskite material comprises FAPbI3, MAPbBr3, or CsPb(I x Br 1-x )3, wherein 0 < x < 1 or more; the precursor solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide or N-methylpyrrolidone.

[0032] Preferably, the doping amount of the trifluoroborate in the perovskite precursor solution is 0.1~10 mg / mL.

[0033] Preferably, in step (2), the annealing temperature is 100~150 ℃ and the time is 10~60 min.

[0034] Preferably, in step (2), during the process of coating the hole transport layer with a trifluoroborate-doped perovskite precursor solution, an antisolvent is added dropwise.

[0035] Preferably, the antisolvent includes diethyl ether, ethyl acetate, chlorobenzene, or anisole.

[0036] Preferably, in step (3), the electron transport material is PC. 61 BM's chlorobenzene solution, the PC 61 The concentration of BM's chlorobenzene solution is 10~30 mg / mL.

[0037] Preferably, in step (3), the annealing temperature is 50-100 ℃ and the time is 5-10 min.

[0038] Preferably, after step (3), the electron transport layer is further coated with an electron transport modification material and annealed to obtain the electron transport modification layer.

[0039] Preferably, the electron transport modifier is an isopropanol solution of BCP, and the concentration of the isopropanol solution of BCP is 0.3~1.0 mg / ml.

[0040] Preferably, the annealing temperature for preparing the electron transport modification layer is 100-150 °C, and the annealing time is 5-10 min.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] (1) The perovskite light-absorbing layer of the organic-inorganic hybrid perovskite solar cell of the present invention contains trifluoroborate, wherein the trifluoroborate contains -BF3 - N atoms, O atoms and uncoordinated Pb in the perovskite light-absorbing layer 2+ Furthermore, strong coordination interactions arise from halide vacancies, with cations in trifluoroborate interacting with uncoordinated I atoms. - / Br - Furthermore, the strong coordination effect generated by cation vacancies can effectively improve the crystallinity and internal defects of perovskite. Simultaneously, trifluoroborate can adjust the energy level matching between the perovskite layer and the charge transport layer, enhancing carrier extraction and transport capabilities and reducing residual stress in the perovskite layer. Moreover, the hydrogen bonding between the F atoms in trifluoroborate and the perovskite effectively improves the intrinsic stability of the perovskite material, thereby further enhancing the photoelectric performance and stability of perovskite solar cells.

[0043] (2) The present invention improves the film quality of the perovskite light-absorbing layer by doping the perovskite precursor solution with trifluoroborate, thereby significantly increasing the open-circuit voltage, current density and fill factor of the prepared solar cell, providing a new method for preparing high-efficiency perovskite solar cell devices.

[0044] (3) The perovskite solar cell of the present invention has a simple preparation process, low cost, excellent photoelectric performance and stability, which is conducive to the commercialization of perovskite solar cells. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the layered structure of the trifluoroborate-doped perovskite solar cell in the embodiment.

[0046] Figure 2 Perovskite solar cells for examples and comparative examples JV Line graph.

[0047] Figure 3 The images show SEM images of the perovskite light-absorbing layers in the examples and comparative examples, where (A) is the SEM image of the perovskite light-absorbing layer in the comparative example; and (B) is the SEM image of the perovskite light-absorbing layer in the examples.

[0048] Figure 4 The images show the AFM images of the perovskite light-absorbing layers in the examples and comparative examples, where (A) is the AFM image of the perovskite light-absorbing layer in the comparative example; and (B) is the AFM image of the perovskite light-absorbing layer in the examples.

[0049] Figure 5 The diagram shows the normalized power conversion efficiency of perovskite solar cells in the examples and comparative examples when stored in air. Detailed Implementation

[0050] To make the objectives, features, and advantages of this invention more readily apparent, specific embodiments of the invention are described in detail below with reference to the accompanying drawings. However, the implementation and protection of this invention are not limited thereto. It should be noted that any processes not specifically described in detail below are methods that can be implemented or understood by those skilled in the art by referring to existing technology.

[0051] This invention provides a trifluoroborate-doped perovskite solar cell. The structure of the perovskite solar cell, from bottom to top, consists of: ITO conductive glass, MeO-2PACz hole transport layer, perovskite light-absorbing layer, and PC. 61 BM electron transport layer, BCP electron transport modification layer, electrode layer.

[0052] The fabrication process of the trifluoroborate-doped perovskite solar cell according to an embodiment of the present invention is as follows:

[0053] Step S1: The etched ITO conductive glass was sequentially ultrasonicated for 30 min each in ultrapure water with cleaning agent, ultrapure water, acetone, and isopropanol. After drying with nitrogen, it was treated with ultraviolet ozone for 20 min to obtain a clean ITO conductive glass substrate. This method utilizes the strong oxidizing properties of O3 generated under microwaves to clean residual organic matter on the ITO surface, while simultaneously increasing the number of oxygen vacancies on the ITO surface, thereby improving the work function of the ITO surface.

[0054] Step S2: Spin-coat an ethanol solution of MeO-2PACz onto the ITO conductive glass surface treated in step S1. The spin-coating speed is 4000 rpm and the spin-coating time is 40 s. Anneal at 120 ℃ for 5 min to obtain the hole transport layer.

[0055] Step S3: Dissolve a certain amount of trifluoroborate in the perovskite precursor solution, heat and stir to obtain a trifluoroborate-doped perovskite precursor solution; drop the prepared trifluoroborate-doped perovskite precursor solution onto the hole transport layer obtained in step S2, spin coat at 1000 rpm for 10 s, then spin coat at 3000 rpm for 30 s, add 200 µL of chlorobenzene as an antisolvent at 25 s, and anneal the substrate coated with the perovskite wet film at 100 ℃ for 50 min to obtain the perovskite light-absorbing layer.

[0056] Step S4: Spin-coat an electron transport layer onto the surface of the perovskite light-absorbing layer.

[0057] Step S5: Spin-coat an electron transport modification layer onto the surface of the electron transport layer.

[0058] Step S6: Deposit a silver electrode on the surface of the electron transport modification layer to obtain an electrode layer with a thickness of 80~100nm.

[0059] After the above steps are completed, a perovskite solar cell doped with trifluoroborate is obtained.

[0060] The superior embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0061] Example

[0062] The structure of the doped perovskite solar cell device in this embodiment is: ITO / SAM / perovskite active layer / PC 61 BM / BCP / Ag.

[0063] The method for preparing trifluoroborate-doped perovskite solar cells in this invention includes the following steps:

[0064] Step S1: The etched ITO conductive glass was sequentially ultrasonicated for 30 min each in ultrapure water with cleaning agent, ultrapure water, acetone, and isopropanol. After drying with nitrogen, it was treated with ultraviolet ozone for 20 min to obtain a clean ITO conductive glass substrate.

[0065] Step S2: Dissolve 0.5 mg of MeO-2PACz (SAM) in 1 mL of anhydrous ethanol and stir at room temperature for 2 h. Take 100 µL of the ethanol solution of MeO-2PACz and drop it onto the ITO substrate. Spin coat at 4000 rpm for 40 s. Anneal the ITO substrate coated with the ethanol solution of MeO-2PACz at 120 °C for 5 min to obtain the hole transport layer.

[0066] Step S3: Dissolve 0.572 g PbI2, 0.1961 g FAI, 0.0067 g MABr, 0.022 g PbBr2, 0.0088 g MACl and 0.0182 g CsI in a mixed solvent of 692 µL DMF and 173 µL DMSO, and add 0.865 mg of trifluoroborate. Stir at 60 °C for 2 h to obtain a 1 mg / mL trifluoroborate-doped perovskite precursor solution. 50 µL of the trifluoroborate-doped perovskite precursor solution was dropped onto the hole transport layer obtained in step S2. The mixture was first spin-coated at 1000 rpm for 10 s, then at 3000 rpm for 30 s. At the 25th s mark, 200 µL of chlorobenzene was added as an antisolvent. The substrate coated with the perovskite wet film was annealed at 100 °C for 50 min to obtain the perovskite light-absorbing layer. The structural formula of the trifluoroborate used in this embodiment is as follows:

[0067]

[0068] Step S4: Add 25 mg PC 61 PC is prepared by dissolving BM in 1 mL of chlorobenzene. 61 BM solution. Add 50 µL of PC 61 BM chlorobenzene solution was dropped onto the perovskite light-absorbing layer obtained in step S3, and spin-coated at 4000 rpm for 30 s. The substrate was then annealed at 100 °C for 5 min to obtain the electron transport layer.

[0069] Step S5: Dissolve 1 mg BCP in 1 mL of isopropanol to prepare a BCP solution. Drop 100 µL of the BCP solution onto the electron transport layer obtained in step S4, spin coat at 4000 rpm for 30 s, and anneal the substrate at 100 °C for 5 min to obtain the electron transport modified layer.

[0070] Step S6: A 100 nm thick layer of silver is deposited on the electron transport modification layer obtained in step S5 using vacuum thermal evaporation technology to obtain a perovskite solar cell doped with trifluoroborate.

[0071] Comparative Example

[0072] The following steps were replaced with the following: 0.572 g PbI₂, 0.1961 g FAI, 0.0067 g MABr, 0.022 g PbBr₂, 0.0088 g MACl, and 0.0182 g CsI were dissolved in a mixed solvent of 692 µL DMF and 173 µL DMSO, and stirred at 60 °C for 2 h to obtain an undoped trifluoroborate perovskite precursor solution. This solution was then dropped onto the hole transport layer obtained in step S2, and spin-coated to obtain an undoped trifluoroborate perovskite light-absorbing layer. All other steps remained the same as in the previous examples.

[0073] Performance testing

[0074] The performance of the perovskite solar cells prepared in the examples and comparative examples was tested under standard test conditions (AM 1.5 G illumination). The photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the obtained perovskite solar cells in the examples and comparative examples are detailed in Table 1.

[0075] Table 1. Performance parameters of the solar cells in the examples and comparative examples.

[0076]

[0077] From Table 1 and Figure 2 It is evident that trifluoroborate doping promotes the improvement of short-circuit current, open-circuit voltage, and fill factor in perovskite solar cell devices, thereby increasing the power conversion efficiency from 22.08% in the comparative example to 24.84% in the embodiment. This result confirms the improvement of photovoltaic performance by trifluoroborate.

[0078] Figure 3 SEM images of the perovskite absorbing layers in the examples and comparative examples are shown, where (A) is the SEM image of the perovskite absorbing layer in the comparative example; and (B) is the SEM image of the perovskite absorbing layer in the examples. Figure 3 A comparison of (A) and (B) shows that trifluoroborate can passivate uncoordinated Pb in perovskites. 2+The defects promote the participation of excess PbI2 (white particles in (A)) in the perovskite crystallization process in the comparative example, and it is completely transformed into perovskite crystals. Furthermore, after trifluoroborate treatment, the perovskite crystals have more regular shapes, larger grain sizes, higher crystallinity, and fewer film defects. All of these will be beneficial to the extraction and transport of charge carriers, thereby improving the photovoltaic performance and stability of the device.

[0079] Figure 4 AFM images of the perovskite absorbing layers in the examples and comparative examples are shown, where (A) is the AFM image of the perovskite absorbing layer in the comparative example; and (B) is the AFM image of the perovskite absorbing layer in the examples. Figure 4 A comparison of (A) and (B) shows that the surface roughness of the perovskite light-absorbing layer in the embodiment is significantly reduced, the film surface is smoother, and the defect density is lower. This is consistent with... Figure 3 The characterization results are consistent.

[0080] from Figure 5 It can be observed that after continuous heating for 1000 hours in a nitrogen atmosphere at 85 °C, the efficiency of the comparative perovskite solar cell is less than 75% of its initial efficiency, while the efficiency of the example perovskite solar cell still maintains more than 95% of its initial efficiency. This significant difference fully demonstrates that trifluoroborate modification can significantly improve the stability of the device.

[0081] This invention is not limited to the specific technical solutions described in the above embodiments and comparative examples. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention (such as the length of the carbon chain, the type of end groups, and the type of cations in the molecular structure of trifluoroborate) are within the scope of protection claimed by this invention.

Claims

1. A trifluoroborate-doped organic-inorganic hybrid perovskite solar cell, comprising, from bottom to top, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode layer, characterized in that, The perovskite light-absorbing layer is doped with trifluoroborate; The structural formula of the trifluoroborate is: Wherein, n is an integer from 1 to 10, R is -CH3, -CH(CH3)2 or -C(CH3)3, and M is Li, Na, K, Rb or Cs.

2. The organic-inorganic hybrid perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell further includes an electron transport modification layer located between the electron transport layer and the electrode layer.

3. The method for preparing an organic-inorganic hybrid perovskite solar cell according to any one of claims 1-2, characterized in that, Includes the following steps: (1) A hole transport material is spin-coated onto a conductive substrate and annealed to obtain a hole transport layer; (2) Coat the hole transport layer obtained in step (1) with a trifluoroborate-doped perovskite precursor solution, anneal, and obtain a perovskite light-absorbing layer. (3) Coat the perovskite light-absorbing layer obtained in step (2) with an electron transport material, and anneal it to obtain an electron transport layer; (4) Electrode material is deposited on the electron transport layer obtained in step (3) to obtain the organic-inorganic hybrid perovskite solar cell.

4. The preparation method according to claim 3, characterized in that, In step (2), the preparation method of the trifluoroborate-doped perovskite precursor solution is as follows: add trifluoroborate to the perovskite precursor solution and heat and stir.

5. The preparation method according to claim 4, characterized in that, The heating temperature is 25~70 ℃, and the stirring time is 15~60 min.

6. The preparation method according to claim 3, characterized in that, In step (2), the perovskite precursor solution includes a perovskite material and a precursor solvent, wherein the perovskite material includes FAPbI3, MAPbBr3, or CsPb(I x Br 1-x )3, wherein 0 < x < 1 or more; the precursor solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide or N-methylpyrrolidone.

7. The preparation method according to claim 6, characterized in that, The doping amount of the trifluoroborate in the perovskite precursor solution is 0.1~10 mg / mL.

8. The preparation method according to claim 3, characterized in that, In step (2), the annealing temperature is 100~150 ℃ and the time is 10~60 min.

9. The preparation method according to claim 3, characterized in that, In step (2), during the process of coating the hole transport layer with a trifluoroborate-doped perovskite precursor solution, an antisolvent is added dropwise.

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