Trans-fabricated perovskite solar cell based on integrated passivation strategy and preparation method thereof

Abstract

The application relates to the technical field of photovoltaic solar cells, in particular to a transverse perovskite solar cell based on an integrated passivation strategy and a preparation method, the structure of the solar cell comprises, from bottom to top, an electrically conductive substrate layer, a hole transport layer, a perovskite active layer, an electron transport layer and a back electrode layer; the perovskite active layer contains a passivation agent molecule, and the passivation agent molecule is selected from any one or several of dimethyl acetonyl phosphonate, methyl acetoacetate, dimethyl ethyl phosphonate, methyl diethyl phosphonate and trimethyl phosphonate. In the application, the passivation molecule is directly introduced into a perovskite precursor solution, and the growth mechanism of the perovskite light-absorbing layer from top to bottom is used, so that the passivation molecule is finally distributed on the upper surface, the bulk phase and the lower surface of the perovskite thin film, and integrated passivation is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic solar cells, in particular to a transverse perovskite solar cell based on an integrated passivation strategy and a preparation method thereof. BACKGROUND

[0002] Perovskite materials are considered as ideal solar energy light absorption materials due to their high absorption coefficient, long carrier lifetime, high carrier mobility, high defect tolerance, and low-temperature solution preparation. In the past decade, the photoelectric conversion efficiency of perovskite cells has been continuously rising, and the certified efficiency has reached 26.1%, which is basically the same as that of single-crystal silicon solar cells. Therefore, perovskite cells are considered as the most promising new generation of photovoltaic technology, and are attracting attention from academia and industry.

[0003] The stability problem of perovskite cells limits their outdoor application. This is because the perovskite material with ionic characteristics inevitably produces various charged defects, such as V I , Pb i , I i , Pb I , I Pb , etc. in the bulk, grain boundary, and surface during the low-temperature solution preparation and rapid nucleation process. These defects not only cause non-radiative recombination processes (Shockley-Read-Hall recombination) in the device, reducing the photoelectric conversion efficiency of the device, but also induce ion migration, causing the device to degrade severely under conditions of temperature, humidity, oxygen, and light, which is not conducive to the stability of the device. Therefore, developing an effective defect passivation strategy is an inevitable choice to achieve high-efficiency and stable perovskite cells.

[0004] So far, various defect passivation strategies have been reported, mainly relying on the formation of coordination bonds, ionic bonds, hydrogen bonds, or two-dimensional / three-dimensional heterojunctions between passivation molecules such as Lewis acids, Lewis bases, ionic liquids, and organic ammonium salts and perovskite materials to achieve defect passivation. In these passivation strategies, there are two ways to introduce passivation molecules: 1) adding them directly to the perovskite precursor solution to achieve bulk defect passivation; 2) forming a thin film of passivation molecules at the interface by means of spin coating, evaporation, and other steps to achieve defect passivation at the upper / lower interface. However, these methods are difficult to achieve defect passivation in the bulk, upper interface, and lower interface at the same time by one introduction method, and these organic passivation molecules can usually only combine with a single active site on the perovskite surface, with weak binding ability. SUMMARY

[0005] To address the shortcomings of existing technologies, this invention provides an inverted perovskite solar cell and its fabrication method based on an integrated passivation strategy. This invention directly introduces passivation molecules into the perovskite precursor solution, and through the top-down growth mechanism of the perovskite light-absorbing layer, ultimately distributes the passivation molecules on the upper surface, bulk phase, and lower surface of the perovskite thin film, achieving integrated passivation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an inverted perovskite solar cell based on an integrated passivation strategy. The structure of the solar cell, from bottom to top, includes: a conductive substrate layer, a hole transport layer, a perovskite active layer, an electron transport layer, and a back electrode layer. The perovskite active layer contains passivating agent molecules, which are selected from any one or more of dimethyl pyruvate, methyl acetoacetate, dimethyl ethyl phosphonoacetate, diethyl phosphonoacetate, and trimethyl phosphate acetate.

[0008] The structural formulas of the passivation molecules are as follows:

[0009]

[0010] Preferably, the material of the hole transport layer is selected from nickel oxide (NiOx), cuprous oxide (Cu2O), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), polyethylenedioxythiophene-polystyrene sulfonate (PEDOT:PSS), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACZ), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz), [4-(9H-carbazole-9-yl)butyl]phosphonic acid (4PACz), [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [4-(3,6-dibromo-9H-carbazole-9-yl)butyl]phosphonic acid (Br-4PACz), [2 ... [6-Dichloro-9H-carbazole-9-yl)ethyl]phosphoric acid (Cl-2PACz), [2-(3,6-dibromo-9H-carbazole-9-yl)ethyl]phosphoric acid (Br-2PACz), [2-(3,6-diiodo-9H-carbazole-9-yl)ethyl]phosphoric acid (I-2PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphoric acid (Me-4PACz), [2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl]phosphoric acid (Me-2PACz), (4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazole-7-yl)butyl)phosphonic acid (MeO-4PADBC), [4-(2,7-dibromo-9,9-dimethylacridine)butyl]phosphonic acid (DMAcPA)

[0011] Preferably, the material of the electron transport layer is selected from tin oxide, titanium oxide, zinc oxide, niobium oxide, methyl (6,6)-phenylcarbon-61-butyrate (PCBM), 10-phenanthroline (BCP), and fullerene C. 60 (C 60 Any one or more of the following.

[0012] Preferably, the preparation of the perovskite active layer includes: mixing the precursor liquid with the passivating agent molecules and then spin-coating it onto the hole transport layer, adding an antisolvent during the spin-coating process, and finally annealing to obtain the final product.

[0013] Preferably, the precursor solution comprises a solute and a solvent, wherein the solute is selected from one or more of cesium iodide, rubidium iodide, methylammonium bromide, formamidinium hydroiodate, lead iodide, and bromide iodide.

[0014] Preferably, the mass ratio of the solute to the volume ratio of the passivating agent molecules in the precursor solution is (940-950):(6-12) mg / ul.

[0015] Preferably, the spin coating process of the precursor liquid and the passivating agent molecules being mixed and then spin-coated onto the hole transport layer is as follows: spin coating at an acceleration of 1000 rpm / s and at rotation speeds of 1000 rpm and 4500 rpm for 10 s and 40-50 s, respectively.

[0016] Preferably, the specific process of adding the antisolvent during spin coating is as follows: when there are 10 seconds left in the total spin coating time, the antisolvent is added.

[0017] Preferably, the antisolvent is selected from any one or more of anisole, chlorobenzene, methyl benzoate, ethyl acetate, propyl acetate, o-methyl anisole, and methyl formate.

[0018] Secondly, the present invention provides a method for fabricating an inverted perovskite solar cell based on an integrated passivation strategy, comprising the following steps:

[0019] S1. Process the conductive substrate layer;

[0020] S2. Deposit a hole transport layer on the conductive substrate layer;

[0021] S3. Deposit a perovskite active layer on the hole transport layer: Mix the precursor liquid with the passivating agent molecules and spin-coat it onto the hole transport layer. Add an antisolvent during the spin-coating process and finally anneal to obtain the final product.

[0022] S4. Deposit an electron transport layer on the perovskite active layer;

[0023] S5. Deposit a back electrode layer on the electron transport layer.

[0024] Preferably, the S1 treatment of the conductive substrate layer specifically involves: cleaning the conductive substrate, drying it with a protective atmosphere, and then treating it with ultraviolet ozone.

[0025] Preferably, the precursor solution of S3 includes a solute and a solvent, wherein the solute is selected from one or more of cesium iodide, rubidium iodide, methylammonium bromide, formamidinium hydroiodate, lead iodide, and bromide iodide.

[0026] Preferably, the solvent is selected from DMF and DMSO in a volume ratio of 4:1.

[0027] Preferably, the amount of passivating agent molecules in S3 is 6 to 12 μL. Exemplarily, the amount of passivating agent molecules is any one of 6 μL, 9 μL, or 12 μL, or a value between two of them.

[0028] Preferably, the specific process of adding the antisolvent during the spin coating process in step S3 is as follows: when there are 10 seconds left in the total spin coating time, the antisolvent is added.

[0029] Preferably, the process of depositing the electron transport layer in S4 specifically involves depositing a PCBM layer first, followed by depositing a BCP layer.

[0030] The beneficial effects of this invention are:

[0031] The inverted perovskite solar cell of this invention contains passivating agent molecules in the perovskite active layer. Utilizing the top-down growth mechanism of the perovskite light-absorbing layer, the passivating molecules can be distributed across the upper, bulk, and lower surfaces of the perovskite film, achieving integrated passivation. Simultaneously, the passivating molecules possess multiple binding sites, enhancing their binding affinity to the perovskite light-absorbing layer and improving the passivation effect. Furthermore, it can effectively regulate the crystal growth of the perovskite film, reduce defect state density, and suppress non-radiative recombination, ultimately improving the photoelectric conversion efficiency and stability of the solar cell.

[0032] This invention targets inverted perovskite solar cells as the structure, aiming to improve device stability by combining defect passivation strategies with a more stable device configuration, thereby advancing the commercialization of perovskite solar cells. Attached Figure Description

[0033] Figure 1 TOF-SIMS characterization images of the perovskite films obtained in Example 1 and the reference group (aO - Distribution, bP - Distribution ().

[0034] Figure 2 Electron microscope images of the upper surface of the perovskite thin film obtained in Example 1 and the reference group.

[0035] Figure 3 Electron microscope images of the lower surface of the perovskite thin film obtained in Example 1 and the reference group.

[0036] Figure 4 Fourier transform-infrared spectra of the passivation molecule of Example 3 and the perovskite thin film of Example 3.

[0037] Figure 5 The images show the UV-Vis absorption spectra of the perovskite films obtained in Example 3 and the reference group.

[0038] Figure 6 X-ray diffraction patterns of the perovskite thin films of the reference group and Example 4.

[0039] Figure 7 The reference group and Example 2 are space charge-limited current diagrams based on purely electronic devices.

[0040] Figure 8 The statistical distribution diagram shows the photovoltaic characteristic parameters of 50 sets of devices from Example 1 and the reference group. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solution of the invention, the invention will be further described in detail below with reference to specific embodiments.

[0042] Example 1

[0043] This embodiment provides a method for fabricating an inverted perovskite solar cell based on an integrated passivation strategy, including the following steps:

[0044] (1) Cleaning of transparent conductive substrate: The indium-doped tin oxide (ITO) substrate was ultrasonically treated with deionized water, isopropanol, acetone and anhydrous ethanol in sequence; after 40 min, the substrate was dried with nitrogen and treated with ultraviolet ozone for 25 min.

[0045] (2) Depositing a hole transport layer on a conductive substrate: Sequentially depositing nickel oxide (NiO) on the above-mentioned ITO substrate. x A hole transport layer was obtained by annealing a NiOx solution with a 2-(3,6-dimethoxy-9H-carbazole-9-yl)ethylphosphonic acid (Meo-2PACz) film at 100 °C for 15 min. The NiOx solution was prepared by using water at a concentration of 10 mg / ml and a volume of 15–40 μL. The Meo-2PACz solution was prepared by using isopropanol at a concentration of 0.5 mg / ml and a volume of 15–40 μL.

[0046] (3) Depositing a perovskite active layer on the hole transport layer: 19.5 mg cesium iodide (CsI), 15.9 mg rubidium iodide (RbI), 8.4 mg methylammonium bromide (MABr), 219.5 mg formamidinium hydroiodate (FAI), 656.9 mg lead iodide (PbI2), and 27.5 mg bromide iodide (PbBr2) were dissolved in 1 ml of... A mixed solution of DMF and DMSO (volume ratio 4:1) was stirred for 1 hour. 6 μL of dimethyl acetone phosphonate passivating agent molecules were added to the stirred solution, and stirring continued for 6 hours. After filtering with an organic filter head with a pore size of 0.22 μm, the substrate was spin-coated at an acceleration of 1000 rpm / s and rotation speeds of 1000 rpm and 4500 rpm for 10 seconds and 40 seconds, respectively. At a total spin-coating time of 40 seconds, 110 μL of the anti-solvent anisole was added dropwise. At the end of the spin-coating time, the substrate was placed on a hot plate at 110 °C for annealing for 20 minutes.

[0047] (4) Deposit an electron transport layer on the above perovskite active layer: Take 20 μL of PCBM (2,9-dimethyl-4,7-biphenyl-1)-chlorobenzene solution with a concentration of 20 mg / mL and spin-coat it onto the surface of the perovskite active layer cooled to room temperature. The spin-coating speed is 3000 rpm, the acceleration is 1500 rpm / s, and the spin-coating time is 30 s. Take 50 μL of BCP (10-phenanthroline)-isopropanol solution with a concentration of 0.5 mg / mL and spin-coat it onto the PCBM film. The spin-coating speed is 6000 rpm, the acceleration is 4000 rpm / s, and the spin-coating time is 40 s.

[0048] (5) A 100 nm silver (Ag) layer is deposited on the electron transport layer as a back electrode, with a vacuum degree <1×10⁻⁶. -4 Pa, speed is

[0049] Example 2

[0050] Same as Example 1, except that the volume of dimethyl acetone phosphonate used in step (3) of Example 1 is 9 μL.

[0051] Example 3

[0052] Same as Example 1, except that the volume of dimethyl acetone phosphonate used in step (3) of Example 1 is 12ul.

[0053] Example 4

[0054] Same as Example 1, except that in step (3) of Example 1, acetone phosphonate dimethyl ester is replaced with acetoacetate methyl ester.

[0055] Example 5

[0056] Same as Example 1, except that in step (3) of Example 1, acetone phosphonate dimethyl ester is replaced with ethylphosphonoacetic acid dimethyl ester.

[0057] Example 6

[0058] Same as Example 1, except that in step (3) of Example 1, dimethyl acetone phosphonate is replaced with diethylphosphonoacetate.

[0059] Example 7

[0060] Same as Example 1, except that in step (3) of Example 1, acetone phosphonate dimethyl ester is replaced with trimethyl phosphate acetate.

[0061] Example 8

[0062] Same as Example 1, except that: in step (3) of Example 1, dimethyl acetone phosphonate was replaced with dimethyl ethyl phosphonoacetate; the perovskite solution was filtered with an organic filter head with a pore size of 0.22 μm and then spin-coated at an acceleration of 1000 rpm / s and rotation speeds of 1000 rpm and 4500 rpm for 10 s and 50 s respectively; when the total spin-coating time was 50 s, 110 μL of the anti-solvent anisole was added; when the spin-coating time was over, the substrate was placed on a hot plate at 110 °C for annealing for 20 min.

[0063] Reference group

[0064] Same as Example 1, except that: no acetone dimethyl phosphonate passivating agent molecule was added in step (3).

[0065] Example 1: Characterization of integrated passivation performance

[0066] The perovskite films obtained in Example 1 and the reference group were characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS) to obtain the elemental distribution, see [link to relevant documentation]. Figure 1 .Depend on Figure 1 O in a - The distribution of these features can help distinguish the approximate locations of the upper surface, bulk phase, and lower surface (Buried Interface) of the perovskite film. Figure 1 As can be seen from b, compared with the reference group (without added dimethyl acetone phosphonate), the phosphorus strength in Example 1 is stronger, and it is distributed on the upper surface, bulk phase and lower surface of the perovskite, and shows an enriched distribution on the lower surface. This indicates that after introducing passivating molecules, it is possible to passivate defects on the upper surface, bulk phase and lower surface of the perovskite at the same time.

[0067] Figure 2 and Figure 3 Electron microscopy images of the upper and lower surfaces of the perovskite films obtained in Example 1 and the reference group, respectively. Figure 2 and Figure 3 It is evident that the film particle size in Example 1 is larger and more uniform than that in the reference group, and the film surface is smoother. Therefore, it can be concluded that the present invention achieves integrated passivation.

[0068] Example 2: Characterization of passivation molecular binding properties

[0069] Fourier transform infrared spectroscopy (FTIR) can be used to test the interaction between passivation molecules and perovskite films. The interaction between the passivation molecules and perovskite in Example 3 was collected and verified using FTIR, such as... Figure 4 As shown, on the one hand, dimethyl pyruvate at 1257 cm⁻¹ -1The characteristic tensile vibration peak of P=O appears at a certain point. When this peak is introduced into perovskite materials, the vibration wavenumber of P=O shifts to 1244 cm⁻¹. -1 Furthermore, the peak value significantly decreased; on the other hand, the C=O group of the dimethyl pyruvate molecule at 1716 and 1648 cm⁻¹... -1 Symmetric and asymmetric tensile vibrations will occur. When this passivation molecule is introduced into perovskite materials, these two characteristic peaks shift to 1709 and 1625 cm⁻¹, respectively. -1 The vibrational peaks of the aforementioned groups shift to lower wavenumbers due to a partial electron cloud shift from P=O and C=O to Pb in the perovskite. 2+ The migration indicates that the passivation molecule can chemically interact with the perovskite simultaneously through both C=O and P=O. Therefore, the FTIR results confirm that the passivation molecule has multiple binding sites, enhancing its interaction with the perovskite light-absorbing layer.

[0070] Figure 5 The images show the UV-Vis absorption spectra of the perovskite films obtained in Example 3 and the reference group. It can be seen that the perovskite film with added dimethyl acetone phosphonate exhibits stronger absorption in the 600-800 nm spectral range compared to the reference group, confirming that this passivation molecule can enhance its binding ability with the perovskite light-absorbing layer and significantly improve the light absorption of the perovskite film, thus potentially leading to superior device performance.

[0071] Example 3: Crystal growth and defect state density characterization of perovskite thin films

[0072] Figure 6 The X-ray diffraction (XRD) patterns of the perovskite films from the reference group and Example 4 are shown. Both exhibit characteristic diffraction patterns of cubic FAPbI3, indicating that the introduction of methyl acetoacetate did not affect the crystal structure of the perovskite film. Notably, the ratio of diffraction intensity of the (100) plane (2θ = 14.18°) to the (110) plane (2θ = 20.2°) of the perovskite film in the reference group was 1.47, while the ratio in Example 4 was 0.52. This suggests that the passivating molecules can effectively regulate the crystal growth of the perovskite film. Furthermore, from Figure 3 This conclusion can also be drawn from the increase in morphology and grain size of the perovskite film.

[0073] Figure 7 Examples 2 and the reference group are space charge-limited current maps (SCLC) based on purely electronic devices. The trap fill limit voltage (V) at the inflection point is used. TFL This allows us to obtain the defect state density (N) inside the device. t ):

[0074]

[0075] Where ε0 is the vacuum permittivity, ε is the relative permittivity, e is the elementary charge, and L is the thickness of the perovskite film (700 nm). Figure 7 It can be seen that V of the reference group TFL It is 1.20V, while the V in Example 2 is 1.20V. TFL It is 0.79. According to the formula above, V... TFL The reduction means that the defect state density (N) t The passivation molecules in this invention effectively reduce defect state density and suppress nonradiative recombination.

[0076] Example 4: Battery Performance and Stability Test

[0077] Figure 8 This is a statistical distribution diagram of the photovoltaic characteristic parameters of 50 sets of devices from Example 1 and the reference group. The current-voltage test conditions for the devices were: room temperature and pressure, nitrogen atmosphere, and AM 1.5G test spectrum. It can be seen that, compared to the reference group, the open-circuit voltage (V) in Example 1 is significantly lower. OC Fill factor (FF), current density (J) SC Both the photoelectric conversion efficiency (PCE) and the related parameters are significantly improved, and the statistical distribution of the parameters is narrower, which fully demonstrates that the solar cell prepared by this invention has better performance.

[0078] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An inverted perovskite solar cell based on an integrated passivation strategy, wherein the structure of the solar cell comprises, from bottom to top: The invention comprises a conductive substrate layer, a hole transport layer, a perovskite active layer, an electron transport layer, and a back electrode layer, characterized in that the perovskite active layer contains a passivating agent molecule, wherein the passivating agent molecule is selected from any one or more of dimethyl acetone phosphonate, methyl acetoacetate, dimethyl ethyl phosphonoacetate, diethyl phosphonoacetate, and trimethyl phosphate acetate.

2. The inverted perovskite solar cell according to claim 1, characterized in that, The hole transport layer is made of NiO. x Any one or more of Cu2O, PTAA, PEDOT:PSS, MeO-2PACZ, MeO-4PACz, 4PACz, 2PACz, Br-4PACz, Cl-2PACz, Br-2PACz, I-2PACz, Me-4PACz, Me-2PACz, MeO-4PADBC, and DMAcPA.

3. The inverted perovskite solar cell according to claim 1, characterized in that, The electron transport layer is made of materials selected from tin oxide, titanium oxide, zinc oxide, niobium oxide, PCBM, BCP, and C. 60 Any one or more of them.

4. The inverted perovskite solar cell according to any one of claims 1 to 3, characterized in that, The preparation of the perovskite active layer includes: mixing the precursor liquid with the passivating agent molecules and then spin-coating it onto the hole transport layer, adding an antisolvent during the spin-coating process, and finally annealing to obtain the final product.

5. The inverted perovskite solar cell according to claim 4, characterized in that, The precursor solution includes a solute and a solvent, wherein the solute is selected from one or more of cesium iodide, rubidium iodide, methylammonium bromide, formamidinium hydroiodate, lead iodide, and bromide iodide.

6. The inverted perovskite solar cell according to claim 4, characterized in that, The mass ratio of the solute to the volume ratio of the passivating agent molecules in the precursor solution is (940-950):(6-12) mg / ul.

7. The inverted perovskite solar cell according to claim 4, characterized in that, The spin coating process of the precursor liquid and the passivating agent molecules being mixed and then spin-coated onto the hole transport layer is as follows: spin coating is performed at an acceleration of 1000 rpm / s and at rotation speeds of 1000 rpm and 4500 rpm for 10s and 40-50s, respectively.

8. The inverted perovskite solar cell according to claim 4, characterized in that, The specific process of adding the antisolvent during spin coating is as follows: when there are 10 seconds left in the total spin coating time, add the antisolvent.

9. The inverted perovskite solar cell according to claim 4, characterized in that, The antisolvent is selected from any one or more of anisole, chlorobenzene, methyl benzoate, ethyl acetate, propyl acetate, o-methyl anisole, and methyl formate.

10. A method for fabricating an inverted perovskite solar cell based on an integrated passivation strategy, characterized in that, Includes the following steps: S1. Process the conductive substrate layer; S2. Deposit a hole transport layer on the conductive substrate layer; S3. Deposit a perovskite active layer on the hole transport layer: Mix the precursor solution with the passivating agent molecules and spin-coat it onto the hole transport layer. Add an antisolvent during the spin-coating process and finally anneal to obtain the passivating agent molecule. The passivating agent molecule is selected from any one or more of dimethyl pyruvate, methyl acetoacetate, dimethyl ethyl phosphonoacetate, diethyl phosphonoacetate, and trimethyl phosphate acetate. S4. Deposit an electron transport layer on the perovskite active layer; S5. Deposit a back electrode layer on the electron transport layer.

Images