Method for improving dispersibility of SAM layer and optimizing perovskite thin film by mixing SAM molecules

Abstract

The invention discloses an innovative method for optimizing the dispersion uniformity of an SAM layer by mixing two different types of SAM molecules in the process of preparing a trans-perovskite solar cell so as to improve the quality of a perovskite thin film and improve the efficiency of a trans-PSC device. According to the method, Me-4Pacz SAM molecules and N-(phosphoric acid methyl) glycine which are independently used originally are mixed to prepare a mixed SAM solution, and through matching of the two different SAM molecules, the self-aggregation tendency of each SAM molecule is reduced, the uniformity of the SAM layer is optimized, and the quality of the perovskite thin film is optimized. In the process, the perovskite thin film obtained by depositing perovskite on a more uniform SAM layer substrate is superior to the perovskite thin film obtained by depositing a single SAM molecular substrate in grain size and distribution. And the grain size and distribution are optimized, so that effective extraction and transmission of photon-generated carriers at an interface are ensured, and recombination of the carriers is reduced. By virtue of the excellent characteristics, the photoelectric conversion efficiency of the perovskite device is improved from 21.89% to 23.20% by virtue of a mixed SAM molecular strategy. The research provides a new thought and direction for preparing a uniform and high-quality perovskite solar cell from trans-SAM-based perovskite through a simple method, and the practical application of the perovskite technology is facilitated.

Description

Technical Field

[0001] The present invention relates to the development and application fields of inverted perovskite solar cells. Specifically, it involves improving the dispersibility of the SAM layer by mixing two different types of SAM molecules, enhancing the quality of the perovskite thin film prepared by subsequent spin coating, and improving the photoelectric conversion efficiency of the fabricated device. Background Art

[0002] In 2019, a team led by Steve Albrecht developed a self-assembled monolayer (SAM) containing phosphonic acid and carbazole groups and applied it as a p-type functional layer in inverted perovskite solar cells. Experiments found that such SAMs could replace or supplement traditional poly(triarylamine) (PTAA) and NiO x . The introduction of self-assembled monolayers (SAMs) has greatly promoted the progress of inverted perovskite solar cell technology. The SAM layer optimizes the contact between the traditional perovskite layer and the solid-state p-type hole transport layer, while improving the energy level matching at their interface, thereby enhancing the efficiency of hole extraction. However, the uneven distribution and poor coverage of the substrate surface caused by the amphiphilicity of SAM molecules may lead to uneven nucleation and growth of the perovskite layer, increase interface defects, increase the probability of non-radiative recombination, reduce the open-circuit voltage and fill factor of the battery, and cause inconsistencies in battery performance, affecting the long-term stability of the battery. These drawbacks seriously affect the photoelectric conversion efficiency and reliability of perovskite solar cells and greatly limit the industrialization process of SAM-based inverted PSCs.

[0003] Therefore, regulating the dispersibility of SAM molecules in solvents to prepare a more uniform SAM layer is crucial for the deposition of high-quality perovskite thin films. Summary of the Invention

[0004] In view of this, the present invention aims to provide a new strategy for improving the dispersion uniformity of the SAM layer, thereby enhancing the quality of the perovskite thin film and increasing the efficiency of inverted PSC devices during the preparation of inverted perovskite solar cells. A uniform SAM layer can promote the uniform adsorption and crystallization of the perovskite precursor solution, reduce defects and pinholes in the thin film, thereby improving the crystallization quality and photoelectric properties of the perovskite thin film. In addition, a uniform SAM layer can also improve the interfacial contact between the perovskite layer and the hole transport layer, reduce the defect density at the interface, and reduce carrier recombination losses, thereby enhancing the efficiency and stability of inverted perovskite solar cells. To achieve the above goals, the present invention includes the following steps:

[0005] Step 1: NiO configured and ultrasonically homogenized xThe aqueous solution was spin-coated evenly on the ITO conductive glass. After the annealing was completed, it was naturally cooled to room temperature to obtain the hole transport layer;

[0006] Step 2: In a nitrogen glove box, the prepared improved SAM solution was spin-coated on the NiO x layer. After the annealing was completed, it was cooled to the ambient temperature to obtain the hole transport layer;

[0007] Step 3: In a nitrogen glove box, the prepared perovskite precursor solution was statically spread on the SAM layer, and an antisolvent was injected by dynamic spin-coating during the window period to prepare the perovskite thin film to obtain the active layer;

[0008] Step 4: In a nitrogen glove box, the prepared upper surface passivator PipI was dynamically spin-coated on the perovskite layer. After annealing, the upper surface passivation layer was obtained;

[0009] Step 5: In a nitrogen glove box, the prepared PCBM solution was statically spread on the PipI layer, spin-coated and annealed, and cooled to the ambient temperature to obtain the electron transport layer;

[0010] Step 6: In a nitrogen glove box, the prepared BCP solution was statically spread on the PCBM layer, spin-coated and annealed, and cooled to the ambient temperature to obtain the hole blocking layer;

[0011] Step 7: Ag was evaporated on the surface of the hole blocking layer (BCP) in Step 6 above as the electrode to prepare the perovskite solar cell.

[0012] In the above preparation method, the ITO glass needs to be pretreated before use. Specifically, it can be: the ITO glass was ultrasonically treated successively with deionized water, acetone, and isopropyl alcohol, then dried with nitrogen and subjected to plasma treatment.

[0013] Preferably in the present invention, the coating method is selected from one or more of dynamic spin-coating, brushing, spraying, and dip-coating; more preferably one or more of dynamic spin-coating, spraying, and dip-coating. In some specific embodiments of the present invention, the coating method is selected as dynamic spin-coating.

[0014] Preferably, the annealing temperature range of NiO in the above Step 1 x is 120 - 130 °C; more preferably 150 - 160 °C; the annealing time corresponds to 20 - 30 min and 10 - 20 min respectively.

[0015] Preferably, in the above step two, the mixing concentration of the mixed SAM (Me-4Pacz: glyphosate) is 0.3 mg Me-4Pacz + 0.1 / 0.3 / 0.5 mg glyphosate per 1 mL; more preferably, 0.3 mg Me-4Pacz + 0.3 mg glyphosate are dissolved in each 1 mL of the SAM solution.

[0016] Preferably, in the above step three, the environmental temperature for dynamic spin coating is 17 - 20 °C; more preferably, it is 18 - 19 °C.

[0017] Preferably, in the above step three, the rotation speed range for dynamic spin coating is 4500 - 6000 rpm; more preferably, it is 5000 - 5500 rpm.

[0018] Preferably, in the above step three, the time for dynamic spin coating is 1000 rpm (1000 rpm / s acceleration) - 10 s - 4500 rpm (1000 rpm / s acceleration) - 40 s; more preferably, it is 1000 rpm (500 rpm / s acceleration) - 10 s - 5000 rpm (2500 rpm / s acceleration) - 40 s.

[0019] Preferably, in the above step four, when preparing the PipI modification layer, the spin coating time is 20 - 40 s, and 80 μL is spin-coated dynamically.

[0020] Preferably, in the above step five, when preparing the PCBM electron transport layer, the concentration is 15 - 25 mg / mL and the spin coating rotation speed is 1800 - 3000 rpm, more preferably the concentration is 20 mg / mL; the spin coating rotation speed is 2000 rpm.

[0021] Preferably, in the above step six, when preparing the BCP hole blocking layer, the concentration is 0.5 mg / mL and the spin coating rotation speed is 3000 - 6000 rpm, more preferably the spin coating rotation speed is 5000 rpm.

[0022] The method for optimizing the dispersion uniformity of the SAM layer and improving the quality of the perovskite film by mixing two different types of SAM molecules only needs to mix different types of SAM molecules in the optimal mass ratio in absolute ethanol and spin coat them on the surface of nickel oxide to complete. The preparation process and equipment are simple, and the preparation conditions are mild.

[0023] The preparation method of the present invention realizes the improvement of the photoelectric conversion efficiency of the perovskite solar cell.

[0024] The present invention has the following advantages and beneficial effects: A new strategy is proposed to optimize the dispersion uniformity of SAM molecules and thus improve the quality of perovskite films by mixing two different types of SAM molecules. This method can be completed by mixing different types of SAM molecules in the optimal mass ratio in absolute ethanol. The preparation process and equipment are simple, and the preparation conditions are mild, which is applicable to large-scale industrial production. This method can simultaneously regulate crystal growth, reduce defect states, and improve the conversion efficiency of perovskite solar cell devices. The invention provides a new idea for improving the quality of SAM-based inverted perovskite films. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the drawings and embodiments.

[0026] Figure 1 It is a process flow chart for preparing a uniform SAM layer by mixing SAM molecules to improve the quality of perovskite films in the present invention;

[0027] Figure 2 It is a scanning electron microscope image and particle size distribution diagram of perovskite films prepared on the original SAM layer and the improved SAM layer in Example 1;

[0028] Figure 3 It is an X-ray diffraction pattern of perovskite films prepared on the original SAM layer and the improved SAM layer in Example 1;

[0029] Figure 4 It is a J-V curve diagram of Cs 0.05 MA 0.1 FA 0.85 PbI3 devices in the dark state;

[0030] Figure 5 It is a steady-state fluorescence spectrum diagram of perovskite films prepared on the original SAM layer and the improved SAM layer in Example 1;

[0031] Figure 6 It is an EIS electrochemical impedance spectrum of Cs 0.05 MA 0.1 FA 0.85 PbI3 devices prepared on the original SAM layer and the improved SAM layer in Example 1;

[0032] Figure 7 Under the condition of simulating sunlight in the atmospheric environment, it is the photo-electrochemical conversion efficiency diagram of Cs 0.05 MA 0.1 FA 0.85 PbI3 devices prepared on the original SAM layer and the improved SAM layer in Example 1. SPECIFIC IMPLEMENTATION MANNER

[0033] To further illustrate this patent, the following describes in detail the method and application of obtaining a uniform SAM layer with a hybrid SAM molecule and preparing a high-quality perovskite solar cell in combination with embodiments.

[0034] Example 1:

[0035] 1. Preparation of the hole transport layer

[0036] In a glove box (water and oxygen content ≤ 0.01 ppm), accurately weigh 10 mg of nickel oxide powder into a reagent bottle. Outside the glove box, add 1 mL of deionized water to prepare a 10 mg / mL nickel oxide solution and seal the bottle mouth with a sealing tape. Sonicate in flowing water for 40 min. Under air conditions, take the filtered (polyethersulfone 0.22 μm water-based filter head) nickel oxide solution and spread it evenly on the substrate. Spin-coat it at a speed of 4000 rpm (acceleration 1000 rpm / s) for 30 s, and place it on a hot stage for annealing at 150 °C for 10 min to prepare a nickel oxide layer. After cooling, transfer it into the glove box.

[0037] In the glove box (water and oxygen content ≤ 0.01 ppm), accurately weigh 0.6 mg of Me-4PACz powder into a reagent bottle, and add 2 mL of absolute ethanol to prepare a 0.3 mg / mL SAM solution; additionally add 0.3 mg of N-(phosphonomethyl)glycine to the improved SAM solution and stir until completely dissolved. In the glove, take the filtered (nylon 66 0.22 μm organic filter head) mixed SAM solution and coat it on the nickel oxide layer. Spin-coat it at a speed of 4000 rpm (acceleration 1000 rpm / s) for 30 s, and place it on a hot stage for annealing at 100 °C for 10 min to prepare a SAM layer.

[0038] 2. Preparation of the perovskite layer

[0039] (1) Prepare the precursor solution: Dissolve (42.34 mg) CsI, (51.83 mg) MAI, (477.6 mg) FAI, (27.51 mg) MACl, and (1.653 g) PbI2 in 2 mL of a mixed solvent of DMF:DMSO at a ratio of 4:1, continuously stir for 6 h, and then filter (nylon 66 0.22 μm organic filter head) for later use;

[0040] (2) In the glove box (water and oxygen content ≤ 0.01 ppm), coat the filtered precursor solution on the SAM layer, and use a multi-step spin-coating procedure to dynamically spin-coat the perovskite at 1000 prm (acceleration 500 rpm / s) for 10 s - 5000 rpm (acceleration 2500 rpm / s) for 40 s, and quickly add 180 μL of CB antisolvent at the 40th second in total time to obtain a liquid film. After the program ends, place it on a hot stage for annealing at 100 °C for 30 min to obtain a perovskite thin film with a thickness of about 600 - 700 nm.

[0041] 3. Preparation of the upper interface passivation layer

[0042] (1) In a glove box (water oxygen value ≤ 0.01 ppm), accurately weigh 1.2 mg of PipI and dissolve it in 4 mL of IPA solution to prepare a 0.3 mg / mL PI interface passivation solution.

[0043] (2) Coat the above solution on the surface of the perovskite layer at a rotation speed of 5000 rpm (acceleration of 1000 rpm / s) for 30 s, and anneal at 100 °C for 10 min to complete the preparation of the interface passivation layer.

[0044] 4. Preparation of the electron transport layer

[0045] (1) In a glove box (water oxygen value ≤ 0.01 ppm), accurately weigh 20 mg of PC 61 BM and dissolve it in 1 mL of chlorobenzene to prepare a 20 mg / mL PCBM solution, stir well, and filter for use.

[0046] (2) Spin-coat the above solution on the surface of the interface passivation layer at a rotation speed of 2000 rpm (acceleration of 1000 rpm / s) for 30 s, and anneal at 100 °C for 5 min to prepare the electron transport layer.

[0047] 5. Preparation of the hole blocking layer

[0048] (1) In a glove box (water oxygen value ≤ 0.01 ppm), accurately weigh 1 mg of BCP and dissolve it in 2 mL of IPA to prepare a 0.5 mg / mL BCP solution, stir well, and filter for use.

[0049] (2) Spin-coat the above solution on the surface of the electron transport layer at a rotation speed of 5000 rpm (acceleration of 1000 rpm / s) for 30 s, and anneal at 100 °C for 5 min to prepare the hole blocking layer.

[0050] 6. Preparation of the Ag electrode

[0051] Using a vacuum evaporation device, evaporate 90 nm of Ag on the hole blocking layer as the electrode, and finally prepare a high-quality perovskite solar cell prepared on a mixed SAM substrate.

[0052] Figure 1This is the process flow chart for preparing high-quality perovskite thin films by mixing different SAM molecules in the present invention. The thin film preparation process is divided into three steps. The first step is to spin-coat a nickel oxide layer on the ITO substrate after UV-ozone treatment and anneal it; the second step is to spin-coat a modified mixed SAM solution on the nickel oxide layer and anneal it; the third step is to spin-coat a perovskite solution above the SAM layer and drop an anti-solvent during the window period to prepare a perovskite liquid film and anneal it. After spin-coating, the nickel oxide layer needs to be annealed at 150 °C for 10 min to completely volatilize the solvent, the modified SAM layer needs to be annealed at 100 °C for 10 min to completely volatilize the solvent, and the perovskite layer needs to be annealed at 100 °C for 30 min to completely volatilize the solvent.

[0053] Figure 2 This is the scanning electron microscope image of the perovskite thin films prepared using the original SAM and the modified SAM solvents in Example 1. Analysis found that the perovskite thin films spin-coated on the basis of the original SAM had smaller grains, while the average grain size of the perovskite thin films spin-coated on the basis of Co-SAM increased from 717 nm to 908 nm, and the grains were dense and uniform. It can be determined that the mixed SAM layer can significantly improve the crystal quality of the perovskite thin films. The prepared high-quality thin films can ensure the extraction and transport of photo-generated carriers at the interface.

[0054] Figure 3 This is the X-ray diffraction pattern of the perovskite thin films prepared on the original SAM layer and the mixed SAM layer in Example 1. In the upper surface XRD pattern, the diffraction peaks corresponding to PbI2 and the (110) plane can be observed at 12.93° and 14.01°. The intensity of the PbI2 peak at this position of the perovskite thin film prepared with the mixed SAM layer decreased significantly compared with that of the perovskite thin film prepared on the original SAM layer. At the same time, the intensity of the diffraction peak of the photoactive phase of the (110) plane increased significantly, indicating that the crystallization quality of the perovskite was improved and the phase transition process was more complete. At the same time, the FWHM of the diffraction peak of the photoactive phase (110) plane shows that the 14.01° FWHM of the perovskite prepared with the mixed SAM decreased from 0.1109 to 0.1047 compared with the FWHM of the original SAM layer, and the decrease in FWHM indicates an increase in grain size and an enhancement of the crystallization orientation, which is consistent with Figure 2 the results of the scanning electron microscope image in

[0055] Figure 4 This is the J-V curve graph of the device prepared on the basis of the original SAM and the mixed SAM layer in Example 1 in the dark state. From the data performance of the perovskite device prepared with the mixed SAM layer, we found a relatively low dark current density, which indicates a reduction in carrier recombination.

[0056] Figure 5Steady-state fluorescence spectra of the perovskite film prepared based on the original SAM and hybrid SAM layers in Example 1. The steady-state fluorescence spectra corresponding to the mixing amount of 0.3 mg / mL glyphosate have the lowest intensity. The number of defects in the film decreases, the crystallinity increases, and the carrier recombination is significantly reduced, enabling the holes excited by the perovskite to be rapidly extracted and transported.

[0057] Figure 6 Electrochemical impedance spectroscopy (EIS) of the device prepared based on the original SAM and hybrid SAM layers in Example 1. Compared with the device with the original SAM layer, the recombination resistance (Rec) of the device prepared with the hybrid SAM increased from 1411 Ω of the device prepared with the original SAM to 2121 Ω. The larger the recombination resistance (Rec), the more difficult the carrier recombination at the device interface, effectively reducing the non-radiative recombination loss of carriers.

[0058] Figure 7 Cs 0.05 MA 0. 1FA 0.85 J-V curve of the device of PbI3 prepared based on the original SAM and hybrid SAM. In the J-V curve measured under simulated air solar radiation, the battery device prepared with the hybrid SAM layer exhibits an optimal conversion efficiency (PCE) of 23.20%. The open-circuit voltage (V oc ) is 1.171, the short-circuit current density (J sc ) is 24.267 mA / cm 2 , and the fill factor (FF) is 81.854%, all of which are superior to the performance of the perovskite device prepared with the original SAM layer.

[0059] The specific implementation manners of this patent do not limit the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a uniform SAM layer by mixing SAM molecules and improving perovskite solar cells, characterized in that Dissolve common SAM molecules such as Me-4Pacz and Co-SAM molecule N-(phosphonomethyl)glycine in 1 mL of absolute ethanol.

2. According to the measure of preparing a uniform SAM layer by mixing SAM molecules and improving perovskite solar cells described in claim 1, the optimal mass ratio of Me-4Pacz and Co-SAM molecule N-(phosphonomethyl)glycine is to dissolve 0.3 mg of Me-4Pacz and 0.3 mg of N-(phosphonomethyl)glycine in 1 mL of absolute ethanol and stir well for 2 hours.

3. A method for preparing a uniform SAM layer with a hybrid SAM molecule and improving a perovskite solar cell, characterized in that, It includes the following steps: 1) Spin-coat the prepared aqueous solution of nickel oxide evenly on ITO. After annealing is completed, cool it naturally to room temperature to obtain a nickel oxide layer; 2) Dissolve Me-4Pacz and N-(phosphonomethyl)glycine with a mass of 0.3 mg + 0.3 mg in 1 mL of absolute ethanol and stir for 2 hours until fully mixed. After filtration, spin-coat it on the nickel oxide layer. After annealing is completed, the preparation of the hole transport layer is completed; 3) In a glove box (water and oxygen value ≤ 0.01 ppm), place the substrate on a spin coater. After statically coating the perovskite precursor solution, start the spin-coating program (1000 rpm - 10 s - 5000 rpm - 40 s). During the window period of the 38th - 40th s of the total time, evenly drop 180 μL of antisolvent CB. Then place the liquid film on a hot plate at 100 °C and anneal for 30 min to obtain a bright perovskite thin film; 4) Spin-coat 0.3 mg / mL PipI interface passivation solution on the surface of the perovskite thin film, and prepare the upper interface passivation layer after annealing; 5) Spin-coat 20 mg / mL PCBM electron transport layer solution on the surface of the interface passivation layer, and prepare the electron transport layer after annealing; 6) Spin-coat 0.5 mg / mL BCP hole blocking layer solution on the surface of the electron transport layer, and prepare the hole blocking layer after annealing; 7) Evaporate Ag on the surface of the hole blocking layer in step 6) above as the electrode to prepare a perovskite solar cell.

4. A measure for preparing a uniform SAM layer by mixing SAM molecules and improving the efficiency of perovskite solar cells according to claim 1, characterized in that Dissolve two different SAM molecules, Me-4Pacz and Co-SAM molecule N-(phosphonomethyl)glycine, with the optimal mass ratio of 0.3 mg of Me-4Pacz and 0.3 mg of N-(phosphonomethyl)glycine in 1 mL of absolute ethanol. After full dissolution, spin-coat to prepare a uniformly distributed SAM layer.

5. A measure for preparing a uniform SAM layer and enhancing a perovskite solar cell by mixing SAM molecules, characterized in that, The coating method selected is one or more of dynamic spin-coating, brushing, spraying, and dip-coating.

6. The measure for preparing a uniform SAM layer and improving a perovskite solar cell by mixing SAM molecules according to claim 3, characterized in that, In step 2), dissolve two different SAM molecules, Me-4Pacz and Co-SAM molecule N-(phosphonomethyl)glycine, with the optimal mass ratio of 0.3 mg of Me-4Pacz and 0.3 mg of N-(phosphonomethyl)glycine in 1 mL of absolute ethanol to prepare a mixed SAM molecule solution; In step 2), the dynamic spin-coating environment is (water and oxygen value ≤ 0.01 ppm); In step 2), the rotational speed range of dynamic spin-coating is 3500 - 5500 rpm; In step 2), the time of dynamic spin-coating is 25 - 35 s; In the step 2), the annealing temperature of the perovskite film is 95 to 110 °C; In the step 2), the annealing time of the perovskite film is 30 to 60 min.

7. A measure for preparing a uniform SAM layer by mixing SAM molecules and improving a perovskite solar cell according to any one of claims 1 to 2 or a measure for preparing a uniform SAM layer by mixing SAM molecules and improving a perovskite solar cell according to any one of claims 3 to 6.

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