A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride

Abstract

The present invention belongs to the field of solar cell technology, and relates to perovskite solar cells, and in particular to a perovskite solar cell passivation method based on 4 ethynylpiperidine hydrochlorides, wherein the present invention adds 4 ethynylpiperidine hydrochlorides in a perovskite precursor or spin-coats 4 ethynylpiperidine hydrochlorides on a perovskite surface. In perovskite film forming process, by introducing 4 ethynylpiperidine hydrochlorides in a precursor, the perovskite crystalline phase of the FA system is preferentially grown in one direction during crystallization, and then presents a layered structure, thereby enhancing the ability of perovskite to resist moisture, and the humidity stability of perovskite light absorbing layer is greatly improved. Meanwhile, it can be passivated by the defect with the surface when used for surface treatment, and then significantly improves the opening pressure of the device, so the present invention both promotes the directional growth of crystal, and can passivate perovskite surface defects, ultimately achieving the improvement of device stability and efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells and relates to a perovskite solar cell, and in particular to a passivation method for a perovskite solar cell based on 4-ethynylpiperidine hydrochloride. Background Art

[0002] Perovskite (PVSK) materials offer advantages such as high light absorption coefficient, long carrier lifetime, tunable bandgap, easy processing, and low cost. In just 10 years, the efficiency of perovskite solar cells has increased from 3% to 25.5%, approaching the efficiency of crystalline silicon solar cells achieved decades ago. However, perovskite solar cells also face several pressing challenges. In particular, perovskite cells are prone to severe decomposition in complex environments such as high temperature and high humidity, leading to device failure and a major factor limiting their commercialization.

[0003] In organic-inorganic hybrid lead-based perovskites, the carboxamidino group (CH(NH2)2 + ,FA + Perovskites have attracted widespread attention due to their near-ideal band gap (1.45-1.51 eV) and excellent thermal stability. However, FAPbI3 perovskites are more sensitive to moisture at room temperature, placing significantly higher demands on the phase deformation nucleus and preparation process. Water erosion can easily cause the crystal structure to collapse, leading to decreased battery performance and stability. Therefore, improving the ability of the α-FAPbI3 phase to resist water erosion is crucial for improving the stability of perovskite batteries.

[0004] Studies have shown that the surface and grain boundaries of perovskites are the most vulnerable sites to decomposition. To solve this problem, researchers have tried many strategies. Common methods are to chemically passivate the perovskite with organic molecules or polymers, or to physically cover structural defects with hydrophobic organic materials to passivate surface defects. These passivation effects are generally achieved by passivating the cations of the perovskite through Lewis acids or Lewis bases and ammonium ion groups. Although they have a certain effect on the stability of the perovskite, they do not improve the stability of the perovskite crystal itself. In addition, the secondary bonds between the passivating molecules and the perovskite surface are usually weak, and their passivation effect is also relatively limited. Therefore, it is particularly important to find a method that can both improve the stability of the perovskite crystal itself and passivate free ions on the surface. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride (4EPHC), which adds 4-ethynylpiperidine hydrochloride to the perovskite precursor or spin-coates 4-ethynylpiperidine hydrochloride on the perovskite surface, thereby promoting the directional growth of crystals and passivating the surface defects of the perovskite, ultimately achieving improved device stability and efficiency.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The present invention provides a perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride. Specifically, when preparing the perovskite solar cell, 4-ethynylpiperidine hydrochloride is dissolved in a perovskite precursor solution to prepare a perovskite film and / or the 4-ethynylpiperidine hydrochloride solution is coated on the surface of the perovskite film to prepare the final perovskite film.

[0008] Preferably, the concentration of 4-ethynylpiperidine hydrochloride in the perovskite precursor solution is 20-100 mg / mL. Further, the concentration of 4-ethynylpiperidine hydrochloride in the perovskite precursor solution is 20 mg / mL or 100 mg / mL.

[0009] Preferably, the concentration of the 4-ethynylpiperidine hydrochloride solution is 0.01-4 mg / mL. Further, the concentration of the 4-ethynylpiperidine hydrochloride solution is 4 mg / mL.

[0010] The molecular formula of the 4-ethynylpiperidine hydrochloride is C7H 12 ClN, the structural formula is as follows:

[0011]

[0012] The present invention's 4EPHC-based perovskite solar cell passivation method can achieve directional crystal growth in organic-inorganic hybrid perovskites, resulting in highly oriented grains. This stabilizes the perovskite phase and improves the stability of the solar cell device. Furthermore, dropwise addition of 4EPHC to the perovskite surface exhibits a passivation effect. This method not only enhances crystallinity during perovskite crystal nucleation but also reacts in situ with exposed ions on the perovskite surface. Experimental results demonstrate that 4-ethynylpiperidine hydrochloride both stabilizes the perovskite phase and passivates perovskite surface defects, thereby simultaneously improving device stability and efficiency.

[0013] Preferably, the solar cell consists of a metal electrode, a hole transport layer, a perovskite thin film light absorption layer, an electron transport layer and ITO conductive glass from top to bottom.

[0014] Preferably, the thickness of the perovskite light absorbing layer is 150-800 nm.

[0015] Preferably, the perovskite precursor solution containing 4-ethynylpiperidine hydrochloride is prepared into a perovskite film by spin coating, and the spin coating speed is 4000-6000 rpm / min and the acceleration is 2000 rpm / s. 2 , the spin coating time is 30s, and 10-40μL of perovskite precursor solution is added per square centimeter.

[0016] Preferably, the 4-ethynylpiperidine hydrochloride solution is spin-coated on the perovskite film by spin coating, with a spin coating speed of 2000-5000 r / min, a time of 10-40 s, and a volume of 20-50 uL of the 4-ethynylpiperidine hydrochloride solution added per square centimeter.

[0017] Preferably, the perovskite film is an organic-inorganic hybrid lead-based perovskite of APbX3, and A is selected from CH3NH 3+ (MA + ), CH(NH2) 2+ (FA + ) and Cs + One or more of, X is selected from one or more of Cl-, Br- and I-.

[0018] Furthermore, the perovskite film is a FAPbI3 organic-inorganic hybrid lead-based perovskite; the preparation method of the perovskite film is: dissolving a mixed powder of 0.8-2.0mmol formamidine hydroiodide (FAI), 0.8-2.0mmol lead iodide (PbI2) and 0.05-0.5mmol formamidine hydrochloride (FACl) in 1mL of a mixed solvent, the volume ratio of the mixed solvent is V(DMF):V(DMSO)=8:1, shaking and stirring at room temperature for 30min to prepare a perovskite precursor solution, and then spin coating to prepare a film.

[0019] More preferably, the hole transport layer is made of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) and has a thickness of 100-300 nm.

[0020] Furthermore, the preparation method of the hole transport layer is: spin-coating the Spiro-OMeTAD hole transport layer precursor liquid onto the perovskite light absorption layer, at a spin coating speed of 2000-6000 rpm and a spin coating time of 20-60s, and adding 10-40 μL of the hole transport layer precursor liquid per square centimeter of the glass sheet.

[0021] 1 mL of the Spiro-OMeTAD hole transport layer precursor solution includes 50-100 mg of Spiro-OMeTAD powder, 5-50 μL of acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide with a concentration of 400-600 mg / L, and 5-50 μL of 4-tert-butylpyridine. The solvent is chlorobenzene.

[0022] More preferably, the ITO conductive glass has a sheet resistance of 5-25Ω and a transmittance of 70-95%.

[0023] More preferably, the ITO conductive glass is firstly ultrasonically cleaned with glass cleaning agent, water, acetone and ethanol in sequence for 10-20 minutes before use, and then treated with ultraviolet ozone for 5-60 minutes after drying.

[0024] More preferably, the electron transport layer material is SnO2, and the film thickness is 10-80 nm.

[0025] Furthermore, the electron transport layer is prepared by spin coating. First, a 15% SnO2 colloidal aqueous solution is diluted to a concentration of 1%-10%, and then spin coated onto the ITO conductive glass. 2 10-80 μL of SnO2 aqueous solution was dropped onto the glass slide, the spin coating speed was 4000 rpm, and the spin coating time was 30 s; after spin coating, the glass slide was placed on a heating table at 180°C for annealing for 30 min.

[0026] More preferably, the metal electrode includes but is not limited to gold and silver, and has a thickness of 50-300 nm. Further, the metal electrode is gold with a purity of 9.9999%.

[0027] More preferably, the metal electrode is prepared by evaporation, and the vacuum degree reaches 1×10 -5 -8×10 -4 Pa after the start of evaporation, Evaporation rate deposition.

[0028] The present invention also provides a perovskite solar cell, which consists of a metal electrode, a hole transport layer, a perovskite thin film light absorption layer, an electron transport layer and ITO conductive glass from top to bottom, and the perovskite thin film light absorption layer is prepared by the above method.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention discloses a perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride, that is, adding 4-ethynylpiperidine hydrochloride to a perovskite precursor or spin-coating 4-ethynylpiperidine hydrochloride on the perovskite surface. Compared with perovskite solar cells that are not doped or surface-treated with 4EPHC, the present invention provides a method that can promote crystal orientation growth at room temperature and can be applied to surface defect passivation. During the perovskite film formation process, by introducing 4-ethynylpiperidine hydrochloride into the precursor, the perovskite crystal phase of the FA system preferentially grows in one direction during crystallization, thereby presenting a layered structure, thereby enhancing the ability of the perovskite to resist moisture and greatly improving the humidity stability of the perovskite light absorption layer. At the same time, when used for surface treatment, it can be passivated by the defects on the surface, thereby significantly improving the device's opening voltage. Therefore, the present invention not only promotes the directional growth of crystals, but also passivates the defects on the perovskite surface, ultimately achieving improved device stability and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 XRD patterns of perovskite films prepared without 4EPHC treatment and after 4EPHC treatment;

[0032] Figure 2 Surface morphologies of perovskite films prepared without 4EPHC treatment (a, b), with 1% 4EPHC added to the precursor (c, d), and with 0.5 mg / mL 4EPHC spin-coated on the surface (e, f).

[0033] Figure 3 The changes of perovskite films prepared without 4EPHC treatment (control) and after adding 1% mol and 5% mol 4EPHC to the precursor under 75% high humidity conditions over time before encapsulation;

[0034] Figure 4 Current-voltage (JV) curves of perovskite solar cells prepared without 4EPHC treatment (Control), with 1% 4EPHC added to the precursor, and with 0.5 mg / mL 4EPHC spin-coated on the surface. DETAILED DESCRIPTION

[0035] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0036] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0037] Example 1 A method for passivating perovskite solar cells by adding 4EPHC to a precursor

[0038] The structure of the battery includes an ITO conductive substrate layer, a SnO2 electron transport layer, an FA system perovskite light absorption layer, a Spiro-OMeTAD hole transport layer and an Au electrode. The specific preparation method includes the following steps:

[0039] (1) Selecting an ITO conductive glass substrate with a square resistance of 5-25Ω, a transmittance of 70-95%, and a size of 1.5 cm × 1.5 cm as the substrate, the ITO conductive substrate was sequentially treated with glass cleaner (2% detergent aqueous solution), deionized water, acetone, and anhydrous ethanol for 15 minutes, then blown dry with nitrogen, and then placed in a UV ozone cleaning machine for UV ozone pretreatment. The UV lamp irradiation wavelength was 185nm, the treatment time was 30 minutes, and then set aside;

[0040] (2) Preparation of electron transport layer

[0041] Dilute a 15% SnO2 colloidal solution six-fold with deionized water and mix thoroughly. For spin coating, drop the diluted SnO2 solution onto the ozone-treated ITO conductive glass and spread the solution completely with a pipette. Spin coat at 4000 rpm for 30 seconds to obtain a 100nm dense SnO2 layer. Anneal the layer at 180°C for 30 minutes, cool naturally to room temperature, and then clean it in a UV-ozone cleaner for 30 minutes before use.

[0042] (3) Preparation of 4EPHC-treated perovskite films

[0043] 1.4 mmol of FAI powder, 1.4 mmol of PbI2 powder, and 0.28 mmol of FACl powder were dissolved in 890 uL of N,N-dimethylformamide (DMF) and 110 uL of dimethyl sulfoxide (DMSO) and stirred at room temperature to prepare a FAPbI3 perovskite precursor solution (where FACl acts as a passivating agent for grain boundaries). Then, 20 mg / mL (1% mol, relative to the concentration of FAI powder) and 100 mg / mL (5% mol, relative to the concentration of FAI powder) of 4EPHC (CAS No. 550378-30-8) solution (solvent: isopropanol) were uniformly mixed with the perovskite solution in a volume ratio of 9:1. Then, 50 μL of the perovskite precursor solution containing 4EPHC was added dropwise onto the SnO2 dense layer and spin-coated at a high speed in a glove box at a spin coating speed of 5000 rpm / min and an acceleration of 2000 rpm / s. 2 After the spin coating, the film was annealed at 150°C for 10 min, and the ambient humidity during annealing was maintained at 20%. After annealing, a 550nm thick perovskite film was obtained, and its surface morphology (SEM test) was as follows Figure 2 As shown in b and c.

[0044] (4) Preparation of hole transport layer

[0045] 72.3 mg of Spiro-OMeTAD, 17.5 μL of 520 mg / mL acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide, and 28.8 μL of 4-tert-butylpyridine were dissolved in 1 mL of chlorobenzene to obtain the Spiro-OMeTAD hole transport layer precursor solution. 60 μL of the precursor solution was then dropped onto the perovskite film at a spin coating speed of 3000 rpm and an acceleration of 1500 rpm / s. 2 , time is 30s, prepare a 100nm hole transport layer, and place it in a nitrogen environment to prepare for blade coating and evaporation (i.e., use a blade to scrape off the thin film at the common electrode, then install the device into a 5×5 evaporation template, place the evaporation template into the evaporation chamber, and evaporation after vacuuming);

[0046] (5) Preparation of metal electrodes

[0047] When the vacuum degree of the evaporation chamber reaches 5×10 -4 After Pa, turn on the heating power and The deposition rate was 80 nm, and the effective area of ​​the cell evaporated by the evaporation template was 0.06 cm 2 , and finally a perovskite solar cell was prepared.

[0048] Example 2 A method for surface treatment of calcium perovskite solar cells based on 4EPHC

[0049] Except for step (3), the remaining preparation steps and methods are the same as those in Example 1.

[0050] Step (3) of this embodiment is: preparing a perovskite solar cell treated with 4EPHC surface

[0051] 1.4 mmol of FAI powder, 1.4 mmol of PbI2 powder, and 0.28 mmol of FACl powder were dissolved in 890 μL of N,N-dimethylformamide (DMF) and 110 μL of dimethyl sulfoxide (DMSO) and stirred at room temperature to prepare a FAPbI3 perovskite precursor solution (where FACl acts as a passivating agent for the grain boundaries). 50 μL of the perovskite precursor solution was then added to the dense SnO2 layer and spin-coated in a glove box at a speed of 5000 rpm / min and an acceleration of 2000 rpm / s. 2 , time is 30s; after the spin coating is completed, annealing is carried out at 150℃ for 10min, and the ambient humidity during annealing is maintained at 20%. After annealing, a perovskite film is obtained.

[0052] After the perovskite film is cooled, 4EPHC surface treatment is performed: 4EPHC is dissolved in isopropanol to prepare a 4EPHC solution with a concentration of 4 mg / mL, and then the 4EPHC solution is spin-coated on the surface of the perovskite film. That is, 20uL of 4EPHC solution is added to the surface of the perovskite film at the 10th second of spin coating. The spin coating speed is 4000rpm / min and the spin coating time is 20s. After spin coating, it is stored in dry air or nitrogen. The surface morphology (SEM test) is as follows Figure 2 As shown in e and f.

[0053] Comparative Example 1 Preparation method of perovskite solar cell without 4EPHC treatment

[0054] Except for step (3), the remaining preparation steps and methods are the same as those in Example 1.

[0055] The step (3) of this comparative example is: preparing the perovskite light absorbing layer

[0056] 1.4 mmol of FAI powder, 1.4 mmol of PbI2 powder, and 0.28 mmol of FACl powder were dissolved in 890 μL of N,N-dimethylformamide (DMF) and 110 μL of dimethyl sulfoxide (DMSO) and stirred at room temperature to prepare a FAPbI3 perovskite precursor solution (where FACl acts as a passivating agent for the grain boundaries). 50 μL of the perovskite precursor solution was then added to the dense SnO2 layer and spin-coated in a glove box at a speed of 5000 rpm / min and an acceleration of 2000 rpm / s. 2After the spin coating, the film was annealed at 150°C for 10 min, and the ambient humidity during annealing was maintained at 20%. After annealing, a perovskite film was obtained, and its surface morphology (SEM test) was as follows Figure 2 As shown in a and b.

[0057] Depend on Figure 2 Comparing images c and d with images a and b clearly shows that Example 1 has significantly improved crystallinity, with clearer grains, improved conductivity, a distinct layered structure, and strong orientation. Comparing images e and f with images a and b shows that many fine particles appear on the surface of Example 2, indicating that 4EPHC has a passivating effect on the perovskite crystal surface.

[0058] At the same time, the perovskite film of comparative example 1 without 4EPHC treatment was used as a control, and the perovskite film prepared by adding 4EPHC to the precursor of example 1 was subjected to XRD test. Figure 1 It can be seen that the characteristic peak intensity of the sample without adding 4EPHC is only 20,000. After adding 4EPHC, the characteristic peak intensity at 14° reaches 100,000, that is, the intensity of the characteristic peak of the perovskite crystal is enhanced by 5 times after adding 4EPHC to the precursor.

[0059] Experimental Example 1 Performance Test

[0060] (1) Humidity stability test

[0061] Taking the perovskite film of comparative example 1 without 4EPHC treatment as the control, the perovskite film prepared by adding 1% mol and 5% mol 4EPHC to the precursor in Example 1 was subjected to humidity stability test (water immersion test), that is, the perovskite film prepared by adding 1% mol and 5% mol 4EPHC to the precursor in Example 1 and the perovskite film sample of comparative example 1 without 4EPHC treatment were immersed in water at the same time, and the different decomposition conditions of the film were observed within 0-25h (4.5h, 9.5h, 22h, 25h). The results are shown in FIG. Figure 3 shown.

[0062] Depend on Figure 3 It can be seen that after 9.5 hours, the film obtained without 4EPHC treatment has undergone significant decomposition, while the film obtained with 4EPHC addition is still intact; after 22 hours, the film obtained without 4EPHC treatment has completely decomposed, while the film obtained with 4EPHC addition is mostly intact. This shows that the moisture stability of the perovskite film has been significantly improved after the addition of the precursor 4EPHC. In addition, uniform and dense perovskite films can be obtained after adding different concentrations of 4EPHC to the precursor solution, indicating that different concentrations of 4EPHC treatment have little effect on the film formation of perovskite.

[0063] (2) Photoelectric performance test

[0064] Under the simulated AM1.5G standard sunlight conditions (light intensity of 100mW / cm 2 ) The current-voltage curve (JV) and photoelectric conversion efficiency of the perovskite solar cells prepared in Examples 1, 2, and 3 were tested respectively. The reverse scanning voltage during the test was 1.3V→-0.1V, and the scanning interval was 20mV. The results are shown in Tables 1 and Figure 4 .

[0065] from Figure 4 From the JV curve, it can be seen that after adding 1% 4EPHC to the precursor or spin-coating 0.5 mg / mL 4EPHC on the surface, the open circuit voltage (V oc ) and fill factor (FF) have been significantly improved. Among them, the cell with 1% 4EPHC added to the precursor has the most significant improvement in efficiency and better performance.

[0066] As shown in Table 1, the photovoltaic performance parameters of the devices in Examples 2 and 3 are superior to those in Comparative Example 1. The photovoltaic efficiencies of the cells treated with 4EPHC in Examples 2 and 3 are 18.55% and 19.33%, respectively, while the photovoltaic efficiency of the untreated cell in Comparative Example 1 is 17.61%.

[0067] Table 1 Photoelectric performance parameters of various perovskite solar cell devices

[0068]

[0069] Note: J sc is the short-circuit current density, V oc is the open circuit voltage, FF is the fill factor, and PCE is the photoelectric conversion efficiency.

[0070] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride, characterized in that: When preparing a perovskite solar cell, 4-ethynylpiperidine hydrochloride is dissolved in a perovskite precursor solution to prepare a perovskite film and / or the 4-ethynylpiperidine hydrochloride solution is coated on the surface of the perovskite film to prepare a final perovskite film; the perovskite film is an organic-inorganic hybrid lead-based perovskite of APbX3, and A is selected from CH3NH3 + (MA + )、CH(NH2)2 + (FA + ) and Cs + One or more of, X is selected from Cl - Br - and I - One or more of .

2. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 1, characterized in that, The concentration of the 4-ethynylpiperidine hydrochloride in the perovskite precursor solution is 20-100 mg / mL.

3. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 1, characterized in that: The concentration of the 4-ethynylpiperidine hydrochloride solution is 0.01-4 mg / mL.

4. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 1, characterized in that: The solar cell consists of a metal electrode, a hole transport layer, a perovskite film light absorption layer, an electron transport layer and ITO conductive glass from top to bottom.

5. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 1, characterized in that: The perovskite precursor solution containing 4-ethynylpiperidine hydrochloride was prepared into a perovskite film by spin coating at a speed of 4000-6000 rpm / min and an acceleration of 2000 rpm / s. 2 The spin coating time was 30 s, and 10-40 μL of perovskite precursor solution was added per square centimeter.

6. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 1, characterized in that: The 4-ethynylpiperidine hydrochloride solution is spin-coated on the perovskite film by spin coating, the spin coating speed is 2000-5000 r / min, the time is 10-40 s, and the volume of the 4-ethynylpiperidine hydrochloride solution added per square centimeter is 20-50 uL.

7. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 4, characterized in that: The hole transport layer is made of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene.

8. A perovskite solar cell passivation method based on 4-ethynylpiperidine hydrochloride according to claim 4, characterized in that: The ITO conductive glass has a square resistance of 5-25 Ω and a transmittance of 70-95%.

9. A perovskite solar cell, characterized in that: The solar cell consists of a metal electrode, a hole transport layer, a perovskite thin film light absorption layer, an electron transport layer and ITO conductive glass from top to bottom, and the perovskite thin film light absorption layer is prepared by the method according to claim 1.

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