Perovskite solar cell based on 2-(diethanolamine) ethanesulfonic acid modification and preparation method and application thereof

Abstract

The invention relates to a perovskite solar cell based on 2-(diethanolamine) ethanesulfonic acid modification and a preparation method and application thereof. The perovskite solar cell sequentially comprises a conductive substrate, a tin dioxide electron transport layer, a 2-(diethanolamine) ethanesulfonic acid (EBS) interface passivation layer, a perovskite light absorption layer, a hole transport layer and a metal electrode layer from bottom to top. Compared with the prior art, the EBS interface passivation layer is constructed between the stannic oxide electron transport layer and the perovskite light absorption layer, so that the dual passivation effect is achieved; the oxygen vacancy defect is passivated through tight combination of a hydroxyl group and the stannic oxide layer; the sulfonic acid group is combined with the perovskite layer to passivate Pb and I ion defects, so that the conductivity of the electron transport layer is improved, energy level matching is promoted, the loss caused by non-radiative recombination is reduced, the residual stress of the perovskite layer is released, and the overall performance of the device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, its preparation method and application. Background Art

[0003] In a typical n-i-p device structure, tin dioxide (SnO2) is used as the electron transport layer. With its advantages such as low-temperature manufacturing characteristics, wide bandgap, high electron mobility, and long-term irradiation stability, it has successfully replaced titanium dioxide and become the core material for constructing high-efficiency n-i-p structure devices. However, the mismatch between the crystal structure and energy levels of tin dioxide and the perovskite layer results in numerous defects at the interface. These defects, as non-radiative recombination centers, seriously affect the recombination of carriers and the interfacial charge transfer efficiency, thereby restricting the performance of the device. In addition, problems such as differences in thermal expansion coefficients, lattice mismatch, and residual stress caused by external stress further exacerbate the decline in the crystallization quality of perovskite, having an adverse impact on the overall performance of the device. Therefore, optimizing the perovskite-tin dioxide interface and solving the interface defect and stress problems have become an urgent need and research focus for improving the performance of perovskite solar cells. Through means such as interface engineering, it is expected to achieve more efficient and stable perovskite solar cells and promote the further development of photovoltaic technology.

[0004] For example, Chinese Patent CN113193124A discloses a perovskite solar cell modified with triethylamine hydrochloride and its preparation method. A triethylamine hydrochloride layer is provided between the tin dioxide electron transport layer and the perovskite light-absorbing layer. On the one hand, it reduces the surface roughness of the tin dioxide electron transport layer and improves the poor interfacial contact problem between the tin dioxide electron transport layer and the perovskite absorption layer. On the other hand, the -NR 3+ and Cl - in the triethylamine hydrochloride layer passivate the charge defects on the surface of the tin dioxide electron transport layer and the bottom of the perovskite absorption layer, improving charge transport. However, the problem of residual stress caused by the difference in thermal expansion coefficients between the tin dioxide electron transport layer and the perovskite light-absorbing layer has not been properly solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, its preparation method and application, which passivate the oxygen vacancy defects of tin dioxide and the Pb and I ion defects of perovskite, solve the interface defect and stress problems, and improve the efficiency of perovskite solar cells.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] On the one hand, the present invention provides a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, which sequentially includes a conductive substrate, a tin dioxide electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode layer from bottom to top. A 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer is further provided between the tin dioxide electron transport layer and the perovskite light-absorbing layer.

[0008] Preferably, the chemical formula of the 2-(diethanolamino)ethanesulfonic acid (EBS) is:

[0009]

[0010] More preferably, the 2-(diethanolamino)ethanesulfonic acid includes a sulfonic acid group (SO3 2- ).) and a hydroxyl group (-OH).

[0011] More preferably, the 2-(diethanolamino)ethanesulfonic acid binds to the tin dioxide layer through the hydroxyl group therein to passivate the oxygen vacancy defects in the tin dioxide, and binds to the perovskite layer through the sulfonic acid group to passivate the Pb and I ion defects.

[0012] In the present invention, a chemical bridge is constructed between the tin dioxide electron transport layer and the perovskite light-absorbing layer by using 2-(diethanolamino)ethanesulfonic acid. The hydroxyl group can bind to the uncoordinated Sn 4+ on the surface of the tin dioxide to passivate the oxygen vacancy defects; the sulfonic acid group can react with the perovskite layer to passivate the Pb and I ion defects; thereby reducing the defects at the buried interface and achieving a dual passivation effect.

[0013] Preferably, the conductive substrate includes FTO, ITO conductive glass, or a PET flexible conductive substrate, and its thickness is 300-800 nm.

[0014] Preferably, the thickness of the tin dioxide electron transport layer is 15-180 nm.

[0015] Preferably, the thickness of the 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer is 10-100 nm.

[0016] Preferably, the perovskite light-absorbing layer includes FAPbI3, MAPbI3, (FA 0.95 MA 0.05 ) 0.95 Cs 0.05 Pb(I 0.95 Br 0.05 )3, Cs 0.05 FA 0.9 MA 0.05 PbI3, FA 0.95 Cs 0.05 PbI3, CsPbI 0.95Br 0.5 、CsPbI2Br, CsPbI3, with a thickness of 200 - 500 nm.

[0017] Preferably, the hole transport layer includes 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, with a thickness of 50 - 200 nm.

[0018] Preferably, the metal electrode layer includes gold, silver or copper, with a thickness of 80 - 120 nm.

[0019] Preferably, the perovskite solar cell is an n-i-p type perovskite solar cell.

[0020] In a second aspect, the present invention provides a method for preparing the perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, comprising the following steps:

[0021] S1: Pretreat the etched conductive substrate;

[0022] S2: Prepare a tin dioxide electron transport layer on the surface of the pretreated conductive substrate;

[0023] S3: Spin-coat and prepare a 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer on the surface of the tin dioxide electron transport layer;

[0024] S4: Spin-coat and prepare a perovskite light-absorbing layer on the surface of the 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer;

[0025] S5: Spin-coat and prepare a hole transport layer on the surface of the perovskite light-absorbing layer;

[0026] S6: Use vacuum evaporation to prepare a metal electrode layer on the surface of the hole transport layer, and the perovskite solar cell is prepared.

[0027] Preferably, in step S1, the pretreatment means: ultrasonically clean the etched conductive substrate in deionized water, absolute ethanol, and isopropanol in sequence, dry it with nitrogen, and then clean it with an ultraviolet ozone cleaner, and the cleaning time of the ultraviolet ozone is 10 - 20 min.

[0028] Further preferably, in step S1, ultrasonically clean in deionized water, absolute ethanol, and isopropanol for 10 - 20 min each.

[0029] Preferably, in step S2, the preparation process of the tin dioxide electron transport layer includes chemical bath deposition, thermal evaporation, atomic layer deposition, and spin-coating. After the tin dioxide electron transport layer is prepared, annealing treatment is required.

[0030] Further preferably, in step S2, the temperature of the annealing treatment is 150 - 200 °C, and the time is 20 - 40 min.

[0031] Further preferably, in step S2, the spin coating method refers to spin coating tin dioxide colloidal nanoparticles to prepare a tin dioxide electron transport layer.

[0032] Preferably, in step S3, the specific process of spin coating the 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer is as follows: Dissolve 2-(diethanolamino)ethanesulfonic acid in a solvent to obtain a 2-(diethanolamino)ethanesulfonic acid solution, spin coat it on the tin dioxide electron transport layer, and perform annealing treatment.

[0033] Further preferably, in step S3, the concentration of the 2-(diethanolamino)ethanesulfonic acid solution is 0.1 - 2 mg / mL, and the solvent is water, ethanol, or isopropanol.

[0034] Further preferably, in step S3, the conditions for spin coating include: the spin coating speed is 2000 - 4000 rpm, and the spin coating time is 20 - 40 s.

[0035] Further preferably, in step S3, the temperature of the annealing treatment is 80 - 120 °C, and the time is 5 - 15 min.

[0036] Further preferably, after the 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer is prepared in step S3, it is treated with an ultraviolet ozone cleaning machine for 10 - 15 min, and then placed in a nitrogen glove box for standby.

[0037] Preferably, in step S4, the specific process of spin coating the perovskite light-absorbing layer is as follows: Weigh the corresponding raw materials according to the molar ratio of each element in the perovskite chemical formula, dissolve them in a solvent to prepare the perovskite precursor solution, spin coat the perovskite precursor solution on the 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer, and perform annealing treatment.

[0038] Further preferably, in step S4, the solvent includes N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or a mixed solution of both.

[0039] Further preferably, in step S4, the conditions for spin coating include: 800 - 1200 rpm, for 5 - 15 s; 4000 - 6000 rpm, for 20 - 40 s.

[0040] Further preferably, in the last 10 - 15 seconds of the spin coating process in step S4, an anti-solvent is dropped in, and the anti-solvent includes chlorobenzene.

[0041] Further preferably, in step S4, the temperature of the annealing treatment is 70 - 200 °C, and the time is 10 - 60 min.

[0042] Preferably, in step S5, weigh 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene powder (Spiro-OMeTAD) and dissolve it in a solvent, add additives and mix evenly, heat and stir at 30 - 50 °C for 5 - 7 h to prepare a hole transport layer solution, and then spin-coat it on the perovskite light-absorbing layer.

[0043] Further preferably, in step S5, in the hole transport layer solution, the concentration of 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene is 5 - 8 mmol / L.

[0044] Further preferably, in step S5, in the hole transport layer solution, the concentration of the additive is 400 - 600 mg / mL.

[0045] Further preferably, in step S5, the additive is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), tert-butylpyridine (TBP), and tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tris(bis(trifluoromethane)sulfonimide) (FK209).

[0046] Further preferably, in step S5, the solvent includes chlorobenzene.

[0047] Further preferably, in step S5, the conditions for spin-coating include: the spin-coating speed is 3000 - 5000 rpm, and the spin-coating time is 20 - 40 s.

[0048] Preferably, in step S6, the parameters for vacuum evaporation are as follows: the evaporation rate is 0.8 - 1.2 Å / s, and the deposition time is 700 - 2000 s.

[0049] In a third aspect, the present invention provides an application of the perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid in the field of solar cells.

[0050] The present invention proposes a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid. The specific method is to introduce an EBS molecule containing hydroxyl and sulfonic acid groups to bridge the tin dioxide electron transport layer and the perovskite light-absorbing layer. The hydroxyl group in the EBS molecule is tightly bound to the tin dioxide electron transport layer, and the hydroxyl group at the other end binds to the perovskite light-absorbing layer. On the one hand, the present invention passivates the oxygen vacancy defects in the tin dioxide electron transport layer, improves its conductivity and carrier transport efficiency, and reduces the energy loss caused by non-radiative recombination; on the other hand, it promotes the good crystallization of the perovskite light-absorbing layer and releases the residual stress, further improving the optoelectronic performance and stability of the device.

[0051] The present invention combines material design, interfacial physical chemistry analysis and device engineering to construct a trinity optimization system of "defect passivation - stress regulation - energy level matching", promoting the leap of perovskite solar cells from the laboratory to practical applications. The present invention uses 2-(diethanolamino)ethanesulfonic acid (EBS) to construct a chemical bridge between the tin dioxide electron transport layer and the perovskite light-absorbing layer. The 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer has a more matching energy level structure with the perovskite light-absorbing layer, promoting the transport efficiency of carriers at the interface; the interfacial engineering simultaneously passivates the defects at the interface of the tin dioxide electron transport layer and the perovskite light-absorbing layer, improving the fill factor of the overall device; the interfacial engineering releases the residual stress of the perovskite light-absorbing layer, further improving the optoelectronic performance and stability of the device.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The present invention uses 2-(diethanolamino)ethanesulfonic acid to bridge the tin dioxide electron transport layer and the perovskite light-absorbing layer, and prepares a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, which can simultaneously passivate the oxygen vacancy defects of tin dioxide and the Pb and I ion defects of perovskite, solve the interface defect and stress problems, and improve the efficiency of perovskite solar cells.

[0054] (2) The 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer adopted by the present invention passivates the oxygen vacancy defects in the tin dioxide layer on the one hand, improves its conductivity and carrier transport efficiency, and reduces the energy loss caused by non-radiative recombination; on the other hand, it promotes the good crystallization of the perovskite layer and releases the residual stress, further improving the optoelectronic performance and stability of the device.

[0055] (3) In the present invention, the roughness of the tin dioxide electron transport layer modified by the 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer is reduced from 7.74 nm to 7.36 nm, improving the interface contact problem between the tin dioxide electron transport layer and the perovskite light-absorbing layer.

[0056] (3) The (n-i-p type) perovskite solar cell prepared by the present invention has a maximum power conversion efficiency of 24.196%; at the same time, its humidity stability (74%) has also been significantly improved.

[0057] (4) The preparation process of the present invention is simple and the cost is low, laying a solid foundation for the efficient and stable commercial application of perovskite solar cells. Description of the Drawings

[0058] Figure 1 It is a schematic diagram of the combination of the EBS molecule as an interfacial passivation layer with the tin dioxide electron transport layer and the perovskite light-absorbing layer in the perovskite solar cell modified by 2-(diethanolamino)ethanesulfonic acid in Example 1 of the present invention.

[0059] Figure 2 It is a schematic diagram of an atomic force microscope (AFM) of the tin dioxide thin film (electron transport layer) and the tin dioxide thin film modified by EBS in the comparative example and Example 1 of the present invention.

[0060] Figure 3 It is a conductivity diagram of the tin dioxide thin film and the tin dioxide thin film modified by EBS in the comparative example and Example 1 of the present invention.

[0061] Figure 4 It is a scanning electron microscope image (SEM) of the perovskite thin film (light-absorbing layer) and the perovskite thin film modified by EBS in the comparative example and Example 1 of the present invention.

[0062] Figure 5 It is a residual stress characterization diagram of the perovskite thin film and the perovskite thin film modified by EBS in the comparative example and Example 1 of the present invention (A-B: GIXRD pattern; C: lattice spacing fitting curve; D: stress change of EBS modification).

[0063] Figure 6 It is the stability tracking of the original perovskite solar cell and the perovskite solar cell modified by EBS at a certain humidity in the comparative example and Example 1 of the present invention.

[0064] Figure 7 It is a volt-ampere characteristic curve (J-V curve) of the original perovskite solar cell and the perovskite solar cell modified by EBS in the comparative example and Example 1 of the present invention. Detailed Embodiments

[0065] This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0066] Unless otherwise specified, the reagents, methods, instruments, and equipment used in the present invention are conventional reagents, methods, instruments, and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0067] A perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, which sequentially includes a conductive substrate, a tin dioxide electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode layer from bottom to top. A 2-(diethanolamino)ethanesulfonic acid interfacial passivation layer is further provided between the tin dioxide electron transport layer and the perovskite light-absorbing layer.

[0068] Its preparation process includes the following steps: cleaning and treating the conductive substrate; preparing the tin dioxide electron transport layer; preparing the EBS (2-(diethanolamino)ethanesulfonic acid) interfacial passivation layer; preparing the perovskite light-absorbing layer; preparing the hole transport layer; preparing the metal electrode layer.

[0069] The present invention will be described in detail below with reference to the accompanying drawings and specific examples.

[0070] Example 1

[0071] A perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, the main preparation steps are as follows:

[0072] (1) Cleaning and treating the conductive substrate: The FTO glass conductive substrate is ultrasonically treated with deionized water, ethanol, and isopropanol in sequence, and the treatment time for each solvent is about 15 minutes to ensure a highly clean state of the substrate surface. After the ultrasonic treatment, the conductive substrate is dried with a nitrogen gas gun to thoroughly remove the residual solvent on the surface. Subsequently, the etched side of the substrate is placed face up and accurately placed in a petri dish for use in subsequent experimental steps. Through the above series of rigorous operation processes, a clean and dry FTO glass conductive substrate that meets the requirements is provided for subsequent experiments.

[0073] (2) Preparation of tin dioxide electron transport layer: In this embodiment, the chemical bath deposition (CBD) method is used to prepare the tin dioxide electron transport layer. First, accurately weigh 0.5 g of urea in a beaker and add 60 ml of deionized water to prepare an aqueous urea solution. Then, add 750 μl of hydrochloric acid and 18 μl of mercaptoacetic acid to the aqueous urea solution, mix well, and perform ultrasonic treatment for 5 minutes. Subsequently, weigh another 0.165 g of urea and add it to the above mixture to form a CBD mother liquor. Finally, mix 60 ml of the CBD mother liquor with 300 ml of deionized water, place it in a container, and vertically place the conductive substrate into the container. Place the container in an oven and heat it at 90 °C for 4.5 h to complete the preparation of the tin dioxide electron transport layer. After the preparation is completed, use deionized water and isopropyl alcohol to perform ultrasonic treatment on the deposited film in sequence, and the treatment time for each solvent is 5 minutes. After ultrasonic treatment, dry the film with nitrogen and place it on an annealing table at 150 °C for annealing treatment for 30 minutes. After annealing is completed, wait for the film to cool and then place it in a petri dish for subsequent experiments. Through the above steps, the efficient and precise preparation of the tin dioxide electron transport layer is achieved, providing a high-quality substrate material for subsequent experiments.

[0074] (3) Preparation of EBS interfacial passivation layer: Weigh 0.5 mg of EBS powder and place it in a small bottle with a capacity of 5 ml, add 1 ml of deionized water, and shake it at room temperature for 4 h. Drop 60 μl of the EBS aqueous solution onto the tin dioxide electron transport layer treated in step (2), set the spin coater to 3000 rpm, and the duration is 30 s. After spin coating is completed, place the film on an annealing table at 100 °C for annealing for 10 minutes to obtain the EBS interfacial passivation layer.

[0075] (4) Preparation of perovskite light-absorbing layer: The composition of the perovskite light-absorbing layer prepared in this embodiment is Cs 0.05 FA 0.9 MA 0.05PbI3. First, accurately weigh 0.3688 g of PbI2, 0.1238 g of FAI, 0.006 g of MAI, 0.011 g of CsI, and 0.013 g of MACl. Place the above-mentioned drugs in a small bottle with a capacity of 5 ml. Subsequently, add 400 μl of DMF and 100 μl of DMSO solution to the bottle, and shake for 8 hours at room temperature to form a uniform perovskite precursor solution. The entire process of preparing the perovskite film is carried out in a nitrogen glove box to ensure an anhydrous and oxygen-free environment. First, clean the wafer processed in step (3) with an ultraviolet ozone cleaner for 15 min to remove surface impurities. After cleaning, transfer the wafer to a spin coater inside the glove box. The spin coating process is divided into two stages: the first stage is set at 1000 rpm for 10 s; the second stage is increased to 5000 rpm for 30 s. Before spin coating, statically drop 20 μl of the perovskite precursor solution, and use chlorobenzene (CB) as an anti-solvent, which is dropped in the last 10 seconds of the spin coating process. After spin coating, anneal the wafer at 100 °C for 30 min to finally obtain a dense and uniform perovskite film. Through the above steps, the efficient preparation of the perovskite light-absorbing layer is successfully achieved.

[0076] (5) Preparation of the hole transport layer: First, accurately weigh 45 mg of Spiro-OMeTAD powder and add it to a small bottle with a capacity of 5 ml. Subsequently, add 500 μl of chlorobenzene solution, 20 μl of TBP solution, 20 μl of lithium salt, and 5 μl of cobalt salt to the bottle and mix evenly. Place the mixed solution in an environment of 40 °C, heat and stir for 6 hours to obtain a uniform and stable hole transport layer solution. Then, on the prepared perovskite film (step 4), coat the hole transport layer by dynamic spin coating. Set the spin coater to 4000 rpm and the spin coating time to 30 s. In the last 10 seconds of the spin coating process, drop the pre-prepared hole transport layer solution (Spiro solution). After spin coating, a uniform hole transport layer can be formed on the perovskite film, which shows a purplish-red luster under light. Through the above steps, the efficient and uniform preparation of the hole transport layer is successfully achieved, laying a solid foundation for the construction of subsequent devices.

[0077] (6) Preparation of the electrode layer: First, place the prepared perovskite solar cell in a vacuum coating machine. After ensuring that the equipment sealing performance and the vacuum environment meet the requirements, heat the silver target to a predetermined temperature to evaporate it. Subsequently, by controlling the evaporation rate of 0.8 - 1.2 Å / s and the deposition time of 750 - 2000 s, silver atoms are evenly deposited on the surface of the perovskite cell to form a dense and uniform silver film. During the coating process, monitor the film thickness in real time to ensure that the thickness of the silver film meets the design requirements. When the thickness of the electrode layer reaches 80 nm, turn off the vacuum evaporation machine, and the preparation of the electrode layer is completed.

[0078] Example 2

[0079] This example prepares Cs 0.05 FA 0.9 MA 0.05 PbI3 perovskite solar cells in the same method as in Example 1, except that in step (2), the tin dioxide solution and deionized water are mixed at a volume ratio of 1:3 to obtain a diluted tin dioxide electron transport layer solution, which is spin-coated on FTO, ITO conductive glass or PET flexible conductive substrate by spin coating method, and annealed at 150 - 200 °C for 30 - 60 minutes to form a tin dioxide electron transport layer.

[0080] Example 3

[0081] This example prepares Cs 0.05 FA 0.9 MA 0.05 PbI3 perovskite solar cells in the same method as in Example 1, except that in step (2), high-purity tin dioxide particles are placed in a resistive thermal evaporation source, the pretreated substrate is placed in the corresponding position in the device, the system is evacuated, the tin dioxide particles are heated to evaporate, and the gaseous tin dioxide is deposited on the substrate. After the system cools down, a uniform and dense tin dioxide electron transport layer is obtained.

[0082] Example 4

[0083] This example prepares Cs 0.05 FA 0.9 MA 0.05 PbI3 perovskite solar cells in the same method as in Example 1, except that in step (3), 0.2 mg of EBS powder is weighed and placed in a vial with a capacity of 5 ml, 1 ml of deionized water is added, and shaken at room temperature for 4 h.

[0084] Example 5

[0085] This example prepares Cs 0.05 FA 0.9 MA 0.05 PbI3 perovskite solar cells in the same method as in Example 1, except that in step (3), 0.8 mg of EBS powder is weighed and placed in a vial with a capacity of 5 ml, 1 ml of deionized water is added, and shaken at room temperature for 4 h.

[0086] Example 6

[0087] This example prepares (FA 0.95 MA 0.05 ) 0.95 Cs 0.05 Pb(I 0.95 Br 0.05)3 perovskite solar cells, the difference is only in step (4), where 0.3457 g of PbI2, 0.1164 g of FAI, 0.004 g of MABr, 0.0131 g of PbBr2, and 0.0097 g of CsI are accurately weighed. The above-mentioned drugs are placed in a small bottle with a capacity of 5 ml. Subsequently, 400 ul of DMF and 100 ul of DMSO solution are added to the bottle, and shaken at room temperature for 8 hours to form a uniform perovskite precursor solution.

[0088] Comparative example

[0089] This example prepares Cs by the same method as in Example 1 0.05 FA 0.9 MA 0.05 PbI3 perovskite solar cells, the difference is only that the experimental process in step (3) is directly omitted; this example is used as a standard sample (Control) for comparison with other examples, and other steps remain unchanged.

[0090] The above examples and comparative examples are analyzed and tested as follows:

[0091] The schematic diagram of a perovskite solar cell modified by 2-(diethanolamino)ethanesulfonic acid in Example 1 is as Figure 1 shown, where EBS is used as an interfacial passivation layer, the hydroxyl group binds to tin dioxide to capture oxygen vacancies; the sulfonic acid group binds to the perovskite layer to passivate Pb and I ion defects.

[0092] Atomic force microscopy (AFM) tests were carried out on the tin dioxide thin film (SnO2) and the EBS-modified tin dioxide thin film (SnO2 / EBS) in the comparative example and Example 1 of the present invention, as Figure 2 shown, the roughness of the EBS-modified tin dioxide thin film is lower, reaching 7.36 nm, while the roughness of the original tin dioxide thin film is 7.74 nm. The construction of the EBS interfacial molecular bridge (passivation layer) improves the interfacial contact problem between the tin dioxide electron transport layer and the perovskite light-absorbing layer.

[0093] Conductivity tests were carried out on the tin dioxide thin film, the EBS-modified tin dioxide thin film in the comparative example and Example 1 of the present invention. As Figure 3 shown, the results show that the conductivity of the EBS-modified thin film has been significantly improved, which increases the carrier mobility and thus effectively reduces the resistance of the thin film.

[0094] Scanning electron microscopy (SEM) tests were carried out on the perovskite thin film, the EBS-modified perovskite thin film in the comparative example and Example 1 of the present invention, as Figure 4 shown, the grain size of the EBS-modified perovskite thin film increases and the grain boundaries decrease, proving the promoting effect of the EBS interfacial molecular bridge on the perovskite layer.

[0095] The perovskite thin films in the comparative example and Example 1 of the present invention, and the perovskite thin films after EBS modification were tested for grazing-incidence X-ray diffraction (GIXRD) patterns. As Figure 5 shown, the diffraction peak of the original perovskite thin film at 31.6° shifted significantly towards a lower angle, proving the existence of residual stress. After EBS modification, the change in the lattice spacing of the perovskite thin film decreased, indicating that EBS molecules effectively alleviated the lattice strain in the PVK thin film; at the same time, specific stress values could be obtained through the fitted line of the lattice spacing, further confirming the improvement effect on lattice strain after EBS modification.

[0096] The stability tracking of the original perovskite solar cells in the comparative example and Example 1, and the perovskite solar cells after EBS modification at a certain humidity is as Figure 6 shown. The efficiency of the modified device could still maintain 74% of the original data after 800 h, while the original device was only 53.7%.

[0097] The current-voltage characteristic curves (J-V curves) of the original perovskite solar cells in the comparative example and Example 1, and the perovskite solar cells after EBS modification are as Figure 7 shown. The power conversion efficiency of the modified device was significantly improved, reaching 24.196%.

[0098] The above description of the embodiments is for enabling those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid, characterized in that: The invention comprises, from bottom to top, a conductive substrate, a tin dioxide electron transport layer, a perovskite light absorption layer, a hole transport layer and a metal electrode layer. A 2-(diethanolamine)ethanesulfonic acid interface passivation layer is also arranged between the tin dioxide electron transport layer and the perovskite light absorption layer.

2. A perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 1, characterized in that: The chemical formula of the 2-(diethanolamino)ethanesulfonic acid is: The 2-(diethanolamino)ethanesulfonic acid combines with the tin dioxide layer through the hydroxyl group therein to passivate the oxygen vacancy defects in the tin dioxide, and combines with the perovskite layer through the sulfonic acid group to passivate the Pb and I ion defects.

3. A perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 1, characterized in that: The conductive substrate includes FTO, ITO conductive glass or PET flexible conductive substrate, and its thickness is 300-800nm; The thickness of the tin dioxide electron transport layer is 15-180 nm; The thickness of the 2-(diethanolamino)ethanesulfonic acid interface passivation layer is 10-100 nm; The perovskite light absorbing layer includes FAPbI3, MAPbI3, (FA 0.95 MA 0.05 ) 0.95 Cs 0.05 Pb(I 0.95 Br 0.05 )3. Cs 0.05 FA 0.9 MA 0.05 PbI3、FA 0.95 Cs 0.05 PbI3、CsPbI 0.95 Br 0.5 , CsPbI2Br, CsPbI3, the thickness of which is 200-500nm; The hole transport layer includes 2,2'7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene and has a thickness of 50-200 nm; The metal electrode layer includes gold, silver or copper, and has a thickness of 80-120 nm.

4. A method for preparing a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1: pre-processing the etched conductive substrate; S2: preparing a tin dioxide electron transport layer on the surface of the pretreated conductive substrate; S3: Spin coating a 2-(diethanolamino)ethanesulfonic acid interface passivation layer on the surface of the tin dioxide electron transport layer; S4: Spin coating the perovskite light absorbing layer on the surface of the 2-(diethanolamino)ethanesulfonic acid interface passivation layer; S5: Spin coating on the surface of the perovskite light absorbing layer to prepare a hole transport layer; S6: preparing a metal electrode layer on the surface of the hole transport layer by a vacuum evaporation method to obtain the perovskite solar cell.

5. The method for preparing a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 4, characterized in that: In step S1, the pretreatment refers to: ultrasonically cleaning the etched conductive substrate in deionized water, anhydrous ethanol, and isopropanol in sequence, drying with nitrogen, and then cleaning it with an ultraviolet ozone cleaning machine, and the ultraviolet ozone cleaning time is 10-20 minutes.

6. The method for preparing a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 4, characterized in that: In step S2, the preparation process of the tin dioxide electron transport layer includes chemical bath deposition, thermal evaporation, atomic layer deposition, and spin coating. After the tin dioxide electron transport layer is prepared, annealing treatment is required; Wherein, the annealing treatment temperature is 150-200°C and the time is 20-40min.

7. The method for preparing a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 4, characterized in that: In step S3, the specific process of preparing the 2-(diethanolamino)ethanesulfonic acid interface passivation layer by spin coating is as follows: dissolving 2-(diethanolamino)ethanesulfonic acid in a solvent to obtain a 2-(diethanolamino)ethanesulfonic acid solution, spin coating the 2-(diethanolamino)ethanesulfonic acid solution on the tin dioxide electron transport layer, and performing annealing treatment; Wherein, the concentration of the 2-(diethanolamino)ethanesulfonic acid solution is 0.1-2 mg / mL, and the solvent is water or ethanol or isopropanol; The spin coating conditions include: a spin coating speed of 2000-4000 rpm and a spin coating time of 20-40 s; The annealing treatment is performed at a temperature of 80-120° C. and for a time of 5-15 minutes.

8. The method for preparing a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 4, characterized in that: In step S4, the specific process of preparing the perovskite light absorbing layer by spin coating is as follows: weighing the corresponding raw materials according to the molar ratio of each element in the perovskite chemical formula, dissolving them in a solvent to prepare the perovskite precursor solution, spin coating the perovskite precursor solution on the 2-(diethanolamino)ethanesulfonic acid interface passivation layer, and performing annealing treatment; Wherein, the solvent includes N,N-dimethylformamide, dimethyl sulfoxide or a mixed solution of the two; The spin coating conditions include: 800-1200 rpm, for 5-15 s; 4000-6000 rpm, for 20-40 s; The annealing treatment is carried out at a temperature of 70-200° C. and for a time of 10-60 min.

9. The method for preparing a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid according to claim 4, characterized in that: In step S5, the specific process of preparing the hole transport layer by spin coating is as follows: weigh 2,2'7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene powder and dissolve it in a solvent, add additives and mix well, heat and stir at 30-50° C. for 5-7 hours to obtain a hole transport layer solution, and then spin coat it on the perovskite light absorption layer; Wherein, in the hole transport layer solution, the concentration of 2,2'7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene is 5-8mmol / L, the concentration of the additive is 400-600mg / mL, and the solvent includes chlorobenzene; The additive is one or more of lithium bis(trifluoromethanesulfonyl imide), tert-butylpyridine, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris(trifluoromethanesulfonyl imide); The spin coating conditions include: a spin coating speed of 3000-5000 rpm and a spin coating time of 20-40 s.

10. Application of a perovskite solar cell modified with 2-(diethanolamino)ethanesulfonic acid as claimed in any one of claims 1 to 3 in the field of solar cells.

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