Perovskite solar cell and preparation method thereof

Abstract

The invention provides a perovskite solar cell and a preparation method thereof, and belongs to the technical field of solar cells. Comprising conductive glass, a SnO2 layer, a bottom-buried interface modification layer, a perovskite layer, an interface passivation layer, a hole transport layer and a metal electrode layer which are sequentially stacked, and the bottom-buried interface modification layer comprises fluorine-containing sylvite sulfonate. According to the invention, a bottom-buried interface is modified by using fluorine-containing potassium sulfonate, and through the effects that F atoms and = N-H in formamidine ions (FA < + >) in a perovskite layer form = N-H...... F hydrogen bonds, sulfonate radicals and uncoordinated Pb < 2 + > in the perovskite layer interact, SnO2 is passivated, and K ions and I ions form ionic bonds, the defects of the SnO2 surface and the perovskite bottom interface are synergistically passivated; according to the invention, non-radiative recombination at the interface is reduced, the transmission performance of the interface is improved, the crystallization process of the upper layer perovskite is improved, and the obtained perovskite device has higher photoelectric conversion efficiency and good stability.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a perovskite solar cell and its fabrication method. Background Technology

[0002] Lead halide perovskite solar cells have attracted much attention in recent years due to their significant advantages of high efficiency and solution-based fabrication. Currently, the highest certified efficiency of devices based on the nip structure has exceeded 26%. In these devices, tin oxide (SnO2) is the optimal choice for the electron transport layer. However, due to the presence of numerous oxygen vacancies and dangling bonds on the tin oxide surface, and because the transport layer can affect the crystal growth of the overlying perovskite film, the SnO2 / perovskite interface (buried interface) requires further modification.

[0003] To address this issue, researchers have employed various methods to optimize the buried interface. These include using two-dimensional materials, amino acid derivatives, small organic molecules, and metal salts. However, some of these modification methods increase interfacial series resistance, others introduce additional ions into the perovskite bulk phase, and still others result in uneven dispersion of small molecules. These materials cannot simultaneously passivate SnO2 surface defects, regulate interfacial energy levels, improve the interface, optimize the perovskite crystallization process, and passivate perovskite bottom interface defects. Therefore, developing modifiers that can synergistically passivate the buried interface and regulate perovskite crystallization is crucial. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a perovskite solar cell and a method for its fabrication. The perovskite solar cell of this invention achieves synergistic passivation of defects at the SnO2 surface and perovskite substrate interface, thereby improving the perovskite crystallization process.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The present invention provides a perovskite solar cell, comprising a conductive glass, a SnO2 layer, a buried interface modification layer, a perovskite layer, an interface passivation layer, a hole transport layer and a metal electrode layer stacked sequentially, wherein the buried interface modification layer comprises a potassium fluorosulfonate salt.

[0007] Preferably, the fluorosulfonate potassium salt is potassium trifluoromethanesulfonate and / or potassium perfluorobutylsulfonate.

[0008] Preferably, the thickness of the buried interface modification layer is 1–3 nm.

[0009] Preferably, the interface passivation layer comprises phenylethylamine hydroiodide.

[0010] Preferably, the thickness of the SnO2 layer is 10–60 nm.

[0011] Preferably, the metal electrode layer comprises Au.

[0012] Preferably, the thickness of the metal electrode layer is 60–200 nm.

[0013] This invention also provides a method for preparing the perovskite solar cell described in the above technical solution, comprising the following steps:

[0014] A SnO2 layer is formed by chemical bath deposition on the surface of conductive glass to obtain an FTO / SnO2 substrate.

[0015] After the FTO / SnO2 substrate is treated with ozone, it is coated with a substrate interface modification aqueous solution to form a substrate interface modification layer. The substrate interface modification aqueous solution contains potassium fluorosulfonate.

[0016] A perovskite layer, an interface passivation layer, a hole transport layer, and a metal electrode layer are sequentially formed on the surface of the buried interface modification layer to obtain the perovskite solar cell.

[0017] Preferably, the concentration of the submerged interface modified aqueous solution is 1–15 mM.

[0018] Preferably, after the coating of the substrate interface modification aqueous solution is completed, annealing is performed at a temperature of 100-150°C for a time of 5-30 minutes.

[0019] The present invention provides a perovskite solar cell, comprising a conductive glass, a SnO2 layer, a buried interface modification layer, a perovskite layer, an interface passivation layer, a hole transport layer and a metal electrode layer stacked sequentially, wherein the buried interface modification layer comprises a potassium fluorosulfonate salt.

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

[0021] This invention utilizes potassium fluorosulfonate to modify the buried interface, through which F atoms interact with formamidinium ions (FA) in the perovskite layer. + =NH forms =NH…F hydrogen bonds in the ) and the sulfonate group reacts with uncoordinated Pb in the perovskite layer. 2+ The interaction, passivation of SnO2, and the formation of ionic bonds between K and I ions achieve synergistic passivation of defects on the SnO2 surface and the perovskite bottom interface, reducing nonradiative recombination at the interface, improving interface transport performance, reducing bottom interface leakage current, optimizing energy level matching at the interface, and improving the crystallization process of the upper perovskite. This significantly reduces the open-circuit voltage loss and hysteresis effect of the device, resulting in perovskite devices with higher photoelectric conversion efficiency and good stability.

[0022] The present invention also provides a method for preparing the perovskite solar cell described in the above technical solution. The preparation method of the present invention is simple to operate and easy to implement for industrial application. Attached Figure Description

[0023] Figure 1 SEM image of PbI2 thin film prepared without buried substrate interface modification layer;

[0024] Figure 2 Here is a SEM image of the PbI2 thin film prepared in Example 1;

[0025] Figure 3 SEM image of the perovskite layer prepared without a buried interface modification layer;

[0026] Figure 4 This is a SEM image of the perovskite layer obtained in Example 1;

[0027] Figure 5 The JV curves are for the perovskite solar cells prepared in Example 1 and Comparative Example 1.

[0028] Figure 6 The JV curves are for the perovskite solar cells prepared in Example 1 and Comparative Example 2.

[0029] Figure 7 The JV curves are for the perovskite solar cells prepared in Comparative Example 1, Example 1, and Comparative Example 3. Detailed Implementation

[0030] The present invention provides a perovskite solar cell, comprising a conductive glass, a SnO2 layer, a buried interface modification layer, a perovskite layer, an interface passivation layer, a hole transport layer and a metal electrode layer stacked sequentially, wherein the buried interface modification layer comprises a potassium fluorosulfonate salt.

[0031] The perovskite solar cell of the present invention includes conductive glass (FTO). The present invention does not impose any particular limitation on the thickness of the conductive glass; commercially available products well known to those skilled in the art can be used.

[0032] The perovskite solar cell of the present invention includes a SnO2 layer.

[0033] In this invention, the thickness of the SnO2 layer is preferably 10 to 60 nm, specifically 10, 20, 30, 40, 50 or 60 nm.

[0034] The perovskite solar cell of the present invention includes a buried interface modification layer.

[0035] In this invention, the potassium fluorosulfonate salt is preferably potassium trifluoromethanesulfonate (TFSK) and / or potassium perfluorobutylsulfonate. The potassium fluorosulfonate salt is placed between the SnO2 and the perovskite layer, which can be used to passivate bottom interface defects, improve interface transport, and optimize the thin film crystallization process, thereby significantly reducing the open circuit voltage loss and hysteresis effect of the device, thus preparing a high-efficiency perovskite solar cell.

[0036] In this invention, the thickness of the buried interface modification layer is preferably 1 to 3 nm, specifically 1, 2 or 3 nm. Since the potassium fluorosulfonate is non-conductive, it should not be too thick.

[0037] The perovskite solar cell of the present invention includes a perovskite layer.

[0038] In this invention, the thickness of the perovskite layer is preferably 600-900 nm, specifically 650, 700 or 750 nm.

[0039] This invention does not specifically limit the type of perovskite layer; any type well-known to those skilled in the art can be used. In a specific embodiment of this invention, the perovskite layer is preferably prepared by a method including the following steps:

[0040] Lead iodide solution was spin-coated onto the surface of the buried interface modification layer, followed by a first annealing to obtain a PbI2 film.

[0041] An organic amine salt solution was coated on the surface of the PbI2 film, and the resulting film was then rapidly transferred from a nitrogen glove box to open air with a relative humidity of 25-35% for a second annealing to obtain the perovskite layer.

[0042] In this invention, the concentration of the lead iodide solution is preferably 1.5M, and the solvent of the lead iodide solution preferably includes N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and the volume ratio of DMF to DMSO is preferably 9:1.

[0043] In this invention, the temperature of the first annealing is preferably 70°C, and the time is preferably 1 minute.

[0044] In this invention, the thickness of the PbI2 film is preferably 100-400 nm, specifically 100, 200, 300 or 400 nm.

[0045] After the first annealing is completed, the present invention preferably cools naturally to room temperature to obtain the PbI2 film.

[0046] In this invention, the organic amine salt solution is preferably prepared from 90 mg FAI (formamidinium iodide), 12 mg MACl (methylammonium chloride) and 1 mL isopropanol.

[0047] In this invention, the organic amine salt solution coating is preferably spin-coated, the spin-coating speed is preferably 1800 rpm, and the spin-coating time is preferably 30 s.

[0048] In this invention, the temperature of the second annealing is preferably 150°C, and the time is preferably 15 min.

[0049] The perovskite solar cell of the present invention includes an interface passivation layer.

[0050] In this invention, the interface passivation layer preferably comprises phenylethylamine hydroiodide (PEAI, CAS No.: 151059-43-7).

[0051] In this invention, the thickness of the interface passivation layer is preferably 5 to 20 nm, specifically 5, 10 or 12 nm.

[0052] The perovskite solar cell of the present invention includes a hole transport layer.

[0053] In this invention, the hole transport layer is preferably Spiro-OMeTAD.

[0054] In this invention, the thickness of the hole transport layer is preferably 150-250 nm, specifically 200, 220 or 250 nm.

[0055] In this invention, the metal electrode layer preferably comprises Au.

[0056] In this invention, the thickness of the metal electrode layer is preferably 60-200 nm, specifically 60, 100, 120 or 150 nm.

[0057] This invention also provides a method for preparing the perovskite solar cell described in the above technical solution, comprising the following steps:

[0058] A SnO2 layer is formed by chemical bath deposition on the surface of conductive glass to obtain an FTO / SnO2 substrate.

[0059] After the FTO / SnO2 substrate is treated with ozone, it is coated with a substrate interface modification aqueous solution to form a substrate interface modification layer. The substrate interface modification aqueous solution contains potassium fluorosulfonate.

[0060] A perovskite layer, an interface passivation layer, a hole transport layer, and a metal electrode layer are sequentially formed on the surface of the buried interface modification layer to obtain the perovskite solar cell.

[0061] The present invention involves chemical bath deposition on the surface of conductive glass to form a SnO2 layer, thereby obtaining an FTO / SnO2 substrate.

[0062] In this invention, the conductive glass is preferably ultrasonically cleaned sequentially with ethanol, water and isopropanol before deposition, and then purged with nitrogen.

[0063] In this invention, the ultrasonic cleaning time for ethanol, water and isopropanol is preferably 15 minutes.

[0064] In this invention, the bath solution for chemical bath deposition is preferably prepared from 200 mL of deionized water, 50 μL of mercaptoacetic acid, 2.5 g of urea, 2.5 mL of hydrochloric acid and 0.55 g of SnCl2·2H2O.

[0065] In this invention, the temperature of the chemical bath deposition is preferably 90°C, and the time is preferably 3 to 6 hours, specifically 3, 4, 5 or 6 hours. The chemical bath deposition is preferably carried out in a water bath.

[0066] After the deposition is completed, the present invention preferably uses water and isopropanol to ultrasonically clean for 5 minutes each, followed by nitrogen purging to obtain a dry substrate. The dry substrate is then annealed (preferably at 180°C for 1 hour) to obtain the FTO / SnO2 substrate.

[0067] After obtaining the FTO / SnO2 substrate, the present invention performs ozone treatment on the FTO / SnO2 substrate and then coats it with a substrate interface modification aqueous solution to form a substrate interface modification layer. The substrate interface modification aqueous solution contains potassium fluorosulfonate.

[0068] In this invention, the submerged interface modification aqueous solution is preferably a potassium trifluoromethanesulfonate aqueous solution and / or a potassium perfluorobutylsulfonate aqueous solution.

[0069] In this invention, the ozone treatment time is preferably 10 to 30 minutes, specifically 10, 20 or 30 minutes, and the purpose of the ozone treatment is to improve the wettability of the substrate surface.

[0070] In this invention, the concentration of the substrate interface modification aqueous solution is preferably 1 to 15 mM, specifically 1, 5, 10 or 15 mM.

[0071] The present invention does not impose any particular limitation on the preparation method of the aqueous solution for the buried interface modification. Any solution preparation method known to those skilled in the art can be used, such as dissolving potassium trifluoromethanesulfonate in deionized water and stirring until fully dissolved.

[0072] In this invention, the coating is preferably spin coating, and the spin coating speed is preferably 2000 to 5000 rpm, specifically 2000, 3000, 4000 or 5000 rpm.

[0073] In this invention, after the coating of the substrate interface modification aqueous solution is completed, annealing is preferably performed. The annealing temperature is preferably 100-150°C, specifically 100, 110, 120, 130, 140 or 150°C, and the annealing time is preferably 5-30 min, specifically 10 min. The purpose of annealing is to remove residual water molecules, promote the full interaction between potassium fluorosulfonate and SnO2, and ensure that the subsequent processes are water-free.

[0074] After forming the buried interface modification layer, the present invention sequentially forms a perovskite layer, an interface passivation layer, a hole transport layer and a metal electrode layer on the surface of the buried interface modification layer to obtain the perovskite solar cell.

[0075] In this invention, the method for preparing the perovskite layer is preferably the same as described above.

[0076] After the perovskite layer is formed, the present invention preferably spin-coates a phenethylamine hydroiodide solution onto the surface of the perovskite layer, and then allows it to stand without annealing to obtain the interface passivation layer.

[0077] In this invention, the concentration of the phenethylamine hydroiodide solution is preferably 1.5 mg / mL, and the solvent of the phenethylamine hydroiodide solution is preferably isopropanol.

[0078] In this invention, the spin coating speed is preferably 5000 rpm and the time is preferably 30 s.

[0079] After forming the interface passivation layer, the present invention preferably spin-coates a hole transport layer solution onto the surface of the interface passivation layer, and then allows it to stand without annealing to obtain the hole transport layer.

[0080] In this invention, the hole transport layer solution is preferably prepared by the following steps: dissolving 72.3 mg Spiro-OMeTAD, 30 μL 4-tert-butylpyridine, and 35 μL of lithium salt solution (acetonitrile solution of lithium bis(trifluoromethanesulfonylimide), 260 mg / mL) in 1 mL of chlorobenzene.

[0081] In this invention, the spin coating speed is preferably 3000 rpm and the time is preferably 30 s.

[0082] After obtaining the hole transport layer, the present invention performs vacuum thermal evaporation on the surface of the hole transport layer to form a metal electrode layer, thereby obtaining the perovskite solar cell.

[0083] In this invention, the vacuum thermal evaporation rate is preferably 0.02 nm / s, and the vacuum level is preferably less than 5 × 10⁻⁶. -4 Pa.

[0084] The present invention also provides the application of the perovskite solar cells described in the above technical solution. The present invention does not have any special limitation on the specific method of application, and any method known to those skilled in the art can be used.

[0085] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0086] Example 1

[0087] The fabrication of perovskite solar cells, with a structure of FTO / SnO2 / TFSK / Perovskite / PEAI / Spiro-OMeTAD / Au, includes the following steps:

[0088] FTO / SnO2 substrates were prepared by sequentially ultrasonically cleaning the FTO substrate with ethanol, water, and isopropanol for 15 min each, followed by nitrogen purging. The FTO substrate was then placed in a chemical bath deposition solution to deposit SnO2 (60 nm thick). The chemical bath solution was prepared by adding 200 mL of deionized water, 50 μL of mercaptoacetic acid, 2.5 g of urea, 2.5 mL of hydrochloric acid, and 0.55 g of SnCl2·2H2O. Deposition was carried out in a 90 °C water bath for 4 h. After deposition, the substrate was ultrasonically cleaned with water and isopropanol for 5 min each, followed by nitrogen purging to obtain a dry substrate. This dried substrate was then annealed at 180 °C for 1 h to obtain the FTO / SnO2 substrate.

[0089] Preparation of the embedded interface modification layer: Potassium trifluoromethanesulfonate was dissolved in deionized water and stirred until fully dissolved to obtain a TFSK interface modification aqueous solution (concentration 10 mM). The FTO / SnO2 substrate was ozone treated for 10 min and then cooled for later use. The TFSK interface modification aqueous solution was spin-coated onto the substrate at 3000 rpm, then heated on a hot stage at 100 °C, and then annealed in air at 110 °C for 10 min to obtain the modified FTO / SnO2 / TFSK substrate. The thickness of the TFSK layer was 1 nm.

[0090] A two-step method was used to prepare a perovskite layer (700 nm thick): a lead iodide solution (1.5 M, solvents including DMF and DMSO, with a volume ratio of DMF to DMSO of 9:1) was statically coated onto FTO / SnO2 / TFSK and annealed at 70 °C for 1 min to obtain a PbI2 film (100 nm thick), which was then cooled and set aside. 100 μL of an organic amine salt solution (90 mg FAI and 12 mg MACl dissolved in 1 mL isopropanol) was dropped onto the PbI2 film and spin-coated (1800 rpm for 30 s). The film was then rapidly transferred from a nitrogen glove box to open air with 30% relative humidity and annealed at 150 °C for 15 min to obtain a black perovskite layer.

[0091] Preparation of the interface passivation layer (10 nm thick): The interface passivation layer was formed on the surface of the perovskite layer by spin coating with phenethylamine hydroiodide solution (1.5 mg / mL, solvent is isopropanol) at 5000 rpm for 30 s, and then left to stand without annealing.

[0092] Preparation of hole transport layer (thickness 200 nm): 72.3 mg Spiro-OMeTAD, 30 μL 4-tert-butylpyridine, and 35 μL lithium salt solution (acetonitrile solution of lithium bis(trifluoromethanesulfonylimide), 260 mg / mL) were dissolved in 1 mL chlorobenzene to obtain hole transport layer solution. Then, the hole transport layer solution was dynamically coated at 3000 rpm for 30 s without annealing.

[0093] Metal electrode fabrication: Prepared using vacuum thermal evaporation at a speed of 0.02 nm / s and a vacuum level below 5 × 10⁻⁶. - 4 The process was carried out at Pa to obtain a 60 nm thick Au electrode, resulting in a perovskite solar cell, which is the target device.

[0094] Example 2

[0095] Same as Example 1, except that the concentration of the TFSK interface-modified aqueous solution is 5 mM.

[0096] Example 3

[0097] Same as Example 1, except that the concentration of the TFSK interface-modified aqueous solution is 15 mM.

[0098] Example 4

[0099] Same as Example 1, except that TFSK is replaced with potassium perfluorobutyl sulfonate.

[0100] Comparative Example 1 (Control Sample)

[0101] Same as Example 1, except that the buried interface modification layer is omitted.

[0102] Figure 1 SEM image of the PbI2 thin film prepared without a buried substrate interface modification layer. Figure 2 The image shows an SEM image of the PbI2 film prepared in Example 1. It can be seen that TFSK interface modification is beneficial to the formation of porous and loose PbI2 films, which will facilitate the downward penetration of organic amine salts and improve the perovskite crystallization process.

[0103] Figure 3 SEM image of the perovskite layer prepared without a buried interface modification layer. Figure 4 The image shows an SEM image of the perovskite layer prepared in Example 1. It can be seen that the perovskite film prepared on the modified substrate in Example 1 has a larger grain size and fewer grain boundaries, which is beneficial to reduce grain boundary defects and reduce non-radiative recombination at the interface.

[0104] Figure 5 The JV curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1 show that the performance parameters of the target device have been significantly improved.

[0105] Comparative Example 2 (TFSK added to PbI2)

[0106] Similar to Example 1, except that TFSK was added to the lead iodide solution, and the concentration of TFSK in the lead iodide solution was 10 mM.

[0107] Figure 6 The JV curves of the perovskite solar cells prepared in Example 1 and Comparative Example 2 show that TFSK buried modification has a better effect. This is because adding TFSK to PbI2 cannot fully passivate defects such as oxygen vacancies in buried tin oxide, resulting in limited improvement in device performance parameters.

[0108] Comparative Example 3 (including embedded interfaces modified with molecules of different functional groups)

[0109] Similar to Example 1, except that TFSK was replaced with methanesulfonic acid, potassium methanesulfonate and potassium trifluoroacetate respectively to obtain perovskite solar cells.

[0110] Figure 7 Table 1 shows the JV curves of the perovskite solar cells prepared in Comparative Examples 1, 1, and 3. It can be seen that -CF3 and K... + and -SO3 - By synergistically passivating defects at the buried interface, the device parameters can be improved.

[0111] Table 1 Performance parameters of perovskite solar cells in Comparative Examples 1, Examples 1-3, and Comparative Example 3

[0112] Embedded decoration Jsc(mA / cm 2 )]]> V oc (V) FF (%) PCE (%) Comparative Example 1 25.76 1.15 80.80 23.99 mesylate 25.89 1.16 80.99 24.27 Potassium methanesulfonate 25.91 1.17 83.00 25.16 Potassium trifluoroacetate 25.85 1.18 83.13 25.25 Example 1 26.06 1.19 83.33 25.82 Example 2 26.06 1.19 81.57 25.25 Example 3 26.25 1.18 82.04 25.48 Example 4 26.16 1.17 82.72 25.39

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 perovskite solar cell, characterized in that, It includes a conductive glass, a SnO2 layer, a buried interface modification layer, a perovskite layer, an interface passivation layer, a hole transport layer, and a metal electrode layer stacked sequentially, wherein the buried interface modification layer includes a potassium fluorosulfonate salt.

2. The perovskite solar cell according to claim 1, characterized in that, The fluorosulfonate potassium salt is potassium trifluoromethanesulfonate and / or potassium perfluorobutylsulfonate.

3. The perovskite solar cell according to claim 1 or 2, characterized in that, The thickness of the buried interface modification layer is 1–3 nm.

4. The perovskite solar cell according to claim 1, characterized in that, The interface passivation layer comprises phenethylamine hydroiodide.

5. The perovskite solar cell according to claim 1, characterized in that, The thickness of the SnO2 layer is 10–60 nm.

6. The perovskite solar cell according to claim 1, characterized in that, The metal electrode layer includes Au.

7. The perovskite solar cell according to claim 1 or 6, characterized in that, The thickness of the metal electrode layer is 60–200 nm.

8. The method for preparing a perovskite solar cell according to any one of claims 1 to 7, characterized in that, Includes the following steps: A SnO2 layer is formed by chemical bath deposition on the surface of conductive glass to obtain an FTO / SnO2 substrate. After the FTO / SnO2 substrate is treated with ozone, it is coated with a substrate interface modification aqueous solution to form a substrate interface modification layer. The substrate interface modification aqueous solution contains potassium fluorosulfonate. A perovskite layer, an interface passivation layer, a hole transport layer, and a metal electrode layer are sequentially formed on the surface of the buried interface modification layer to obtain the perovskite solar cell.

9. The preparation method according to claim 8, characterized in that, The concentration of the aqueous solution used for modifying the subsurface interface is 1–15 mM.

10. The preparation method according to claim 8, characterized in that, After the coating of the substrate interface modification aqueous solution is completed, annealing is performed at a temperature of 100-150℃ for 5-30 minutes.

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