Perovskite solar cell for removing solvent based on chemical method and preparation method thereof

Abstract

The invention provides a perovskite solar cell capable of removing a solvent based on a chemical method and a preparation method of the perovskite solar cell. The perovskite solar cell comprises a bottom electrode, a hole transport layer, a perovskite thin film layer, an electron transport layer and an electrode layer. The chemical method for removing the solvent is to remove the residual solvent dimethyl sulfoxide (DMSO) of the perovskite by adopting an anti-solvent doped with a small amount of acyl chloride. According to the method, the acyl chloride and the DMSO can be subjected to violent reaction, and finally, the DMSO remaining in the perovskite thin film is successfully removed, so that the perovskite thin film with more excellent crystallization performance is prepared, and the high-performance and stable perovskite solar cell is realized. According to the method, acyl chloride is introduced into the anti-solvent to react with DMSO, so that the problem of poor crystallinity and stability caused by DMSO solvent residue in the perovskite film is solved, and the method has a relatively great application prospect in the aspect of large-area preparation of perovskite.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a perovskite solar cell based on chemical solvent removal and a preparation method thereof. Background Art

[0002] Perovskite materials offer advantages such as high light absorption coefficient, long carrier lifetime, and tunable band gap, making them ideal materials for solar cells and other optoelectronic devices. Dimethyl sulfoxide (DMSO) plays a crucial role in the research and preparation of perovskite materials. Due to its high solubility and excellent solubility for a variety of organometallic precursors, it is used as a solvent to homogenize the precursor solution, thereby promoting uniform growth of perovskite crystals. However, due to its high boiling point and strong interaction with lead iodide, DMSO is difficult to completely remove from thin films. Residual DMSO can lead to the formation of pores in perovskite films, compromising their uniformity and density. To address the issue of DMSO residue, researchers have explored various strategies, such as replacing part of DMSO with solid carbohydrazide and manipulating the ratio of DMSO to other solvents in the precursor solution to minimize the negative impact of DMSO residue on perovskite film performance. However, these strategies do not completely address the root cause of DMSO residue. Therefore, controlling and reducing DMSO residue to improve crystal quality is a key step in improving the performance and stability of perovskite solar cells and a major challenge in the development of perovskite devices. Summary of the Invention

[0003] Based on this, the purpose of the present invention is to provide a perovskite solar cell based on chemical removal of solvent and a preparation method thereof, so as to solve the problem of DMSO residue in the process of preparing perovskite cells with anti-solvents. The acyl chloride can react chemically with the residual DMSO in the perovskite film during the addition of the anti-solvent, thereby achieving the effect of eliminating the residual DMSO. The film quality is excellent, with good uniformity and density, and few defects. Finally, a perovskite device is successfully prepared, and the device has good photoelectric performance and excellent stability.

[0004] To achieve the above objectives, the present invention provides a perovskite solar cell based on chemical solvent removal and a preparation method thereof, wherein the perovskite solar cell comprises: a bottom electrode, a hole transport layer, a perovskite thin film layer, an electron transport layer and a metal electrode layer stacked in sequence, and the chemical solvent removal method uses an anti-solvent doped with an acyl chloride concentration of 0.1-2 mg / mL to remove the residual solvent DMSO of the perovskite, wherein the acyl chloride is one or more of oxalyl chloride and pyrophosphoryl chloride.

[0005] As a further improvement of the present invention, the perovskite thin film layer is various types of perovskite materials ABX3, wherein A is one or more of cesium ions, methylamine ions, and formamidine ions, B is one or more of lead ions, tin ions, and germanium ions, and X is one or more of halogen anions and thiocyanate ions.

[0006] As a further improvement of the present invention, the bottom electrode comprises conductive glass indium tin oxide or fluorine-doped tin dioxide conductive glass.

[0007] As a further improvement of the present invention, the hole transport layer is nickel oxide, poly [3- (4-carboxybutyl) thiophene-2,5-diyl], poly (3,4-ethylenedioxythiophene) -polystyrene sulfonic acid, poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine], [2- (9H-carbazol-9-yl) ethyl] phosphonic acid, [2- (3,6-diphenyl-9H-carbazol-9-yl) ethyl] phosphoric acid, 4- (3,6-dimethyl-9H-carbazol-9-yl) butyl] phosphoric acid and (2- (3,6-dimethoxy-9H-carbazol-9-yl) ethyl) phosphonic acid or a mixture of more.

[0008] As a further improvement of the present invention, the electron transport layer is C 60 and one or more of PCBM.

[0009] As a further improvement of the present invention, the metal electrode layer is any one or more of aluminum, titanium, palladium, nickel, chromium, copper, gold and silver.

[0010] To achieve the above objectives, the present invention provides a method for preparing a perovskite solar cell by chemically removing solvents, which is used to prepare the aforementioned perovskite solar cell and specifically comprises the following steps:

[0011] Providing a glass substrate for etching ITO or FTO;

[0012] forming a hole transport layer on the substrate; and

[0013] forming the perovskite thin film layer on the hole transport layer; and

[0014] forming an electron transport layer on the perovskite thin film; and

[0015] A metal electrode layer is formed on the electron transport layer; wherein,

[0016] The formation of the perovskite thin film layer specifically includes:

[0017] Dissolving AX and BX in different molar ratios in a solvent of N,N-dimethylformamide (DMF) and DMSO, with a volume ratio of DMF to DMSO of 4:1, and stirring until the solutes are completely dissolved to obtain a perovskite precursor solution; wherein A is one or more of cesium ion, methylamine ion, and formamidinium ion, B is one or more of lead ion, tin ion, and germanium ion, and X is one or more of halogen anion and thiocyanate ion;

[0018] In a glove box, use a spin coater to spin coat the perovskite precursor solution on the hole transport layer at a speed of 3000-5000 rpm for 30-50 seconds, and then add 20-40 μL / cm2 of the solution at the last 10-15 seconds. 2 An anti-solvent containing an acyl chloride (relative to the substrate size) is then treated on a heating platform at 100-130°C for 15-20 minutes to form a perovskite thin film layer; wherein the acyl chloride is one or more of oxalyl chloride and pyrophosphoryl chloride, and the anti-solvent is chlorobenzene or anisole.

[0019] The beneficial effects of the present invention are as follows: the perovskite solar cell of the present invention adds an anti-solvent doped with a small amount of acyl chloride during the spin coating process of the perovskite precursor solution, and removes the residual DMSO in the perovskite film through a chemical reaction, which not only reduces the formation of holes and improves the quality of the perovskite film, but also reduces the recombination caused by defects, increases the generation of photocurrent in the perovskite solar cell, and further improves the photoelectric conversion efficiency of the solar cell, realizes a perovskite film with better crystallization performance, and thus realizes a perovskite solar cell with better performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the perovskite solar cell of the present invention;

[0021] Figure 2 The figure is a comparison of the hydrogen nuclear magnetic resonance spectra before and after the reaction of pyrophosphoryl chloride and DMSO of the present invention;

[0022] Figure 3 The upper and lower surface and cross-sectional morphology images of the perovskite film in the presence and absence of chlorobenzene containing pyrophosphoryl chloride;

[0023] Figure 4 The performance curves of 1.52 eV bandgap perovskite solar cell devices prepared with and without chlorobenzene containing pyrophosphoryl chloride as antisolvent;

[0024] Figure 5 Performance curves of 1.78 eV wide bandgap perovskite solar cell devices prepared with and without anisole containing pyrophosphoryl chloride as antisolvent. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the following embodiments are given for illustration. It should be noted that the following embodiments do not limit the scope of protection claimed by the present invention.

[0026] The present invention provides an acyl chloride-containing antisolvent for a perovskite light-absorbing layer. The concentration of the acyl chloride in the antisolvent is 0.1 to 5 mg / mL. When used in perovskite solar cells, the additive preferably has a concentration of 0.3 to 2 mg / mL, considering that too low an acyl chloride concentration results in incomplete DMSO removal, while too high an acyl chloride concentration increases the series resistance of the perovskite film, impacting device performance.

[0027] In the perovskite-type ABX3 material, A is one or more of cesium ions, methylamine ions, and formamidine ions, B is one or more of lead ions, tin ions, and germanium ions, and X is one or more of halogen anions and thiocyanate ions.

[0028] The structure of perovskite solar cells from bottom to top includes a conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer and a metal electrode.

[0029] The conductive substrate is one of ITO or FTO. The purchased ITO or FTO glass is ultrasonically cleaned with deionized water, acetone, and isopropyl alcohol in sequence. After being blown dry with nitrogen, the glass is placed in ultraviolet ozone for 10 to 30 minutes.

[0030] The hole transport layer is one or more of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(7H-dibenzo[c,g]carbazole-7-yl)butyl]phosphonic acid (4PADCB), and poly[3-(methylamine butyrate)thiophene] (P3CT-N). The process parameters of the hole transport layer are: rotation speed 3000-5000 rpm, time 20-30 s; annealing process parameters are: annealing temperature 80-120°C, time 5-10 min.

[0031] During the spin coating process of the perovskite film, an acyl chloride antisolvent needs to be added dropwise. The process parameters of the perovskite layer are: a rotation speed of 3000-5000 rpm, a time of 30-50 seconds, and then a 20-40 μL / cm2 dropwise addition at the last 10-15 seconds. 2 The substrate is then treated on a heating platform at 100-130°C for 15-20 minutes to form a perovskite thin film layer; wherein the acyl chloride is one or more of oxalyl chloride and pyrophosphoryl chloride, and the antisolvent is chlorobenzene or anisole.

[0032] The electron transport layer includes C60 layer and TPBi layer, TPBi is a hole blocking layer. 60 The layer thickness is 30~45 nm, the TPBi layer thickness is 6~10 nm, and the C 60 The TPBi layer and the TPBi layer are prepared by thermal evaporation vacuum coating method, which can ensure that the film is more dense and uniform, with the preferred thickness of 30 nm and 6 nm respectively.

[0033] The thickness of the metal electrode is 80-200 nm, and the material is not limited. However, considering the conductivity and work function of the metal, the preferred electrode is an Ag electrode, and the preferred thickness is 100 nm.

[0034] Hereinafter, the perovskite thin film and the method for preparing the perovskite solar cell will be further described through specific examples.

[0035] Example 1

[0036] like Figure 1 As shown, the perovskite solar cell includes an ITO glass substrate 1, a hole transport layer 2, an inorganic perovskite film 3, an electron transport layer 4 and a metal electrode 5 stacked in sequence. The preparation method is as follows:

[0037] A 2.5 cm×2.5 cm glass etched with FTO was used as substrate 1. The glass surface was cleaned by ultrasonic cleaning with deionized water, acetone, and isopropyl alcohol in sequence. After drying with nitrogen, the glass surface was placed in ultraviolet ozone for 20 minutes before use.

[0038] On the treated FTO glass substrate, a hole transport layer 2 was deposited by solution spin coating. This layer, consisting of a MeO-2PACz material layer, was formed by spin coating a MeO-2PACz ethanol solution with a concentration of 0.5 mg / mL at a spin coater speed of 4000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes.

[0039] The perovskite film 3 is spin-coated on the hole transport layer 2. The specific method is as follows:

[0040] Perovskite solution: 15.2 mg of MACI, 12.5 mg of PbCI₂, 19.5 mg of CsI₂, 245 mg of FAI, and 691.5 mg of PbI₂ were dissolved in 1 mL of a 1:4 volume ratio of DMSO and DMF. The solution was stirred to dissolve and filtered through a 0.45 μm PTFE filter before use. Perovskite films were prepared in a glove box by spin coating at 2000 rpm for 10 s followed by 4000 rpm for 20 s. In the last ten seconds, 150 μL of 0.6 mg / mL pyrophosphoryl chloride in chlorobenzene was added dropwise. The film was then transferred to a 120°C hotplate for annealing for 30 min to complete the crystallization of the perovskite film.

[0041] The perovskite film was then passivated and a 0.5 mg / mL isopropanol solution of 1,3-diaminopropane dihydroiodide (PDAI2) was deposited on the perovskite film at a spin coating speed of 4000 rpm for 30 s, followed by annealing at 100 °C for 5 min.

[0042] The electron transport layer 4 is formed on the perovskite film 3 by:

[0043] Vacuum thermal evaporation was used to deposit C with a thickness of 30 nm. 60 layer and a 6 nm TPBi layer.

[0044] A layer of silver is deposited on the electron transport layer 4 by vacuum evaporation as the electrode 5 with a thickness of 100 nm.

[0045] See Figure 2 , which is a comparison of the H NMR spectra of the present invention before and after the reaction of pyrophosphoryl chloride and DMSO. It can be seen that the H in DMSO exhibits a distinct strong peak at 2.58 ppm. However, after the addition of pyrophosphoryl chloride, the 2.58 ppm peak completely disappears, indicating that DMSO is completely removed. A relatively weak peak appears at 2.30 ppm, corresponding to the H in dimethyl chlorosulfonium chloride, the product of the reaction between DMSO and pyrophosphoryl chloride.

[0046] See Figure 3 , which are pictures of the upper and lower surfaces and cross-sectional morphology of the perovskite film in the presence and absence of chlorobenzene containing pyrophosphoryl chloride. Figure 3 (a) Surface morphology of perovskite films prepared with and without chlorobenzene containing pyrophosphoryl chloride as an antisolvent. It can be seen that some holes are generated on the surface of the perovskite film prepared with chlorobenzene as an antisolvent, while the perovskite film prepared with chlorobenzene containing pyrophosphoryl chloride as an antisolvent has almost no holes on the surface and the crystal quality is significantly improved. Residual DMSO causes holes to form on the surface of the perovskite film. Figure 3(b) The bottom interface morphology of the perovskite film prepared with and without chlorobenzene containing pyrophosphoryl chloride as the antisolvent. The residual DMSO is mainly at the bottom interface, so the holes at the bottom interface are more serious than those at the upper interface. Compared with the traditional chlorobenzene antisolvent, the bottom interface morphology of the film prepared with chlorobenzene containing pyrophosphoryl chloride is more uniform and smooth, and the holes are significantly reduced, indicating that pyrophosphoryl chloride can effectively remove the residual DMSO in the perovskite film, obtaining a more uniform, dense, and better crystallized perovskite film. Figure 3 The cross-sectional morphology in (c) also supports the above view.

[0047] See Figure 4 The following are performance curves for perovskite solar cell devices prepared with and without chlorobenzene containing pyrophosphoryl chloride as an antisolvent. Performance testing of the prepared perovskite solar cells revealed that the device with pyrophosphoryl chloride as an antisolvent significantly outperformed the device without pyrophosphoryl chloride, achieving a photoelectric conversion efficiency of 26.14%, an open-circuit voltage of 1.182 V, and a fill factor of 84.52%.

[0048] Example 2

[0049] The structure of the perovskite solar cell device is the same as that in Example 1, and the preparation method is as follows:

[0050] A 2.5 cm×2.5 cm glass etched with ITO was used as substrate 1. The glass surface was cleaned by ultrasonic cleaning with deionized water, acetone, and isopropyl alcohol in sequence. After drying with nitrogen, the glass surface was placed in ultraviolet ozone for 20 minutes before use.

[0051] On the treated ITO glass substrate, a hole transport layer 2 was deposited by solution spin coating. This layer, composed of 4PADCB, was formed by spin coating a 0.5 mg / mL 4PADCB solution in ethanol at a spin coater speed of 4000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes.

[0052] The perovskite film 3 is spin-coated on the hole transport layer 2. The specific method is as follows:

[0053] Perovskite solution: 3.5 mg KSCN, 5 mg MACI, 15 mg PbCI2, 62.4 mg CsI, 165.12 mg FAI, 221.28 mg PbI2, and 264.24 mg PbBr2 were dissolved in 1 mL of a 1:4 volume ratio of DMSO and DMF. The mixture was stirred to dissolve and filtered through a 0.45 μm filter before use. Perovskite films were prepared in a glove box by spin coating at 1000 rpm for 8 s and 3500 rpm for 32 s. Ten seconds before the end of the spin coating, 110 μL of 0.5 mg / mL anisole containing pyrophosphoryl chloride was added dropwise. The film was then heated on a hot plate at 100°C for 15 min to form the perovskite film.

[0054] The perovskite film was then passivated and post-treated by depositing a 1 mg / mL 1,3-diaminopropane dihydroiodide isopropanol solution on the perovskite film at a spin coating speed of 4000 rpm for 30 s, followed by annealing at 100 °C for 5 min.

[0055] The electron transport layer 4 is formed on the perovskite film 3 by:

[0056] Vacuum thermal evaporation was used to deposit C with a thickness of 30 nm. 60 layer and a 6 nm TPBi layer.

[0057] A layer of silver is deposited on the electron transport layer 4 by vacuum evaporation as the electrode 5 with a thickness of 100 nm.

[0058] See Figure 5 The performance curves for 1.78 eV wide-bandgap perovskite solar cells prepared using anisole with and without pyrophosphoryl chloride as an antisolvent are shown in Figure 2. The perovskite solar cells were tested for performance, and the pyrophosphoryl chloride-based antisolvent device significantly outperformed the blank device, achieving a power-to-electricity conversion efficiency of 20.86%, an open-circuit voltage of 1.376 V, and a fill factor of 85.08%.

Claims

1. A perovskite solar cell based on chemical removal of solvent, characterized in that: The perovskite solar cell includes: a bottom electrode, a hole transport layer, a perovskite thin film layer, an electron transport layer and a metal electrode layer stacked in sequence. The chemical method of removing the solvent is to use an anti-solvent doped with an acyl chloride concentration of 0.1-2 mg / mL to remove the residual solvent DMSO of the perovskite, wherein the acyl chloride is one or more of oxalyl chloride and pyrophosphoryl chloride.

2. The perovskite solar cell based on chemical solvent removal according to claim 1, characterized in that: The perovskite thin film layer is various perovskite materials ABX3, wherein A is one or more of cesium ions, methylamine ions and formamidine ions, B is one or more of lead ions, tin ions and germanium ions, and X is one or more of halogen anions and thiocyanate ions.

3. The perovskite solar cell based on chemical solvent removal according to claim 1, characterized in that: The bottom electrode is made of conductive glass indium tin oxide or fluorine-doped tin dioxide conductive glass.

4. The perovskite solar cell based on chemical solvent removal according to claim 1, characterized in that: The hole transport layer is one or more of nickel oxide, poly[3-(4-carboxybutyl)thiophene-2,5-diyl], poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], [2-(9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl]phosphonic acid, 4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid and (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid.

5. The perovskite solar cell based on chemical solvent removal according to claim 1, characterized in that: The electron transport layer is C 60 and one or more of PCBM.

6. The perovskite solar cell based on chemical solvent removal according to claim 1, characterized in that: The metal electrode layer is any one or more of aluminum, titanium, palladium, nickel, chromium, copper, gold and silver.

7. A method for preparing a perovskite solar cell by chemically removing solvents, characterized in that: The method for preparing a perovskite solar cell according to any one of claims 1 to 6 comprises the following steps: Providing a glass substrate for etching ITO or FTO; forming a hole transport layer on the substrate; and forming the perovskite thin film layer on the hole transport layer; and forming an electron transport layer on the perovskite thin film; and A metal electrode layer is formed on the electron transport layer; wherein, The formation of the perovskite thin film layer specifically includes: Dissolving AX and BX in a solvent of N,N-dimethylformamide (DMF) and DMSO in a molar ratio of 4:1, and stirring until the solutes are completely dissolved to obtain a perovskite precursor solution; wherein A is one or more of cesium ion, methylamine ion, and formamidinium ion, B is one or more of lead ion, tin ion, and germanium ion, and X is one or more of halogen anion and thiocyanate ion; In a glove box, use a spin coater to spin coat the perovskite precursor solution on the hole transport layer at a speed of 3000-5000 rpm for 30-50 seconds, and then add 20-40 μL / cm2 of the solution at the last 10-15 seconds. 2 The anti-solvent containing acyl chloride is then treated on a heating platform at 100-130°C for 15-20 minutes to form a perovskite thin film layer; wherein the acyl chloride is one or more of oxalyl chloride and pyrophosphoryl chloride, and the anti-solvent is chlorobenzene or anisole.

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