A stepanakite solar cell with a stepanakite alkaloid as an additive and a preparation method thereof

Abstract

The application provides a perovskite solar cell with Stephania alkaloids as an additive and a preparation method thereof. The perovskite solar cell with Stephania alkaloids as an additive comprises a perovskite light-absorbing layer, and the perovskite light-absorbing layer comprises an additive selected from at least one of sinomine, fangchinoline and berberramine. The perovskite solar cell with Stephania alkaloids as an additive provided by the application has a perovskite light-absorbing layer with high film forming quality, and the open-circuit voltage, fill factor and photoelectric conversion efficiency of the perovskite solar cell are obviously increased. Moreover, the Stephania alkaloid material used is derived from natural products in nature, is non-toxic and is friendly to the environment.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more specifically, to a perovskite solar cell using alkaloids from the genus *Cephalotaxus* as an additive and its preparation method. Background Technology

[0002] With increasing energy demand and growing emphasis on environmental protection, clean and renewable green energy has become a research hotspot. Solar cell devices, which directly convert solar energy into electricity using the photovoltaic effect, have attracted significant attention. Perovskite solar cells offer advantages such as simple fabrication processes, low cost, and diverse types, and their photoelectric conversion efficiency (PCE) has grown rapidly over the past decade. Currently, the PCE of perovskite solar cells has reached a certified 25.7%, comparable to mature silicon solar cells, meeting commercial efficiency requirements. The perovskite light-absorbing layer in perovskite solar cell devices is the site of photogenerated exciton separation, and the quality of the perovskite thin film significantly affects the photoelectric performance of perovskite solar cells. Due to the presence of organic cations in the perovskite composition, it decomposes relatively quickly under external factors (such as light, humidity, stress, and temperature). Furthermore, perovskite has a polycrystalline structure, and the photoactive layer possesses numerous crystal defects, which become recombination sites for photogenerated carriers and channels for water and oxygen penetration, reducing the stability and photoelectric performance of the solar cell. Therefore, high-quality perovskite thin films are a necessary condition for excellent perovskite photovoltaic devices.

[0003] By adding suitable additives to the perovskite precursor solution, the additive molecules interact with the perovskite components, effectively passivating defects and improving the quality of the perovskite thin film. This is of great significance for improving the photoelectric performance and stability of perovskite solar cells. Biomolecules have advantages such as being environmentally friendly, low-cost, widely available, and diverse, making them advantageous as additives for improving the photoelectric performance and stability of perovskite solar cells. Some biomolecular additives have been disclosed in existing technologies. However, although these biomolecular additives can passivate perovskite crystal defects, they are difficult to enrich at perovskite grain boundaries, leading to the accumulation of uncoordinated Pb at the perovskite grain boundaries. 2+ The passivation effect of Pb cluster defects is limited, thus its effect on improving the performance of perovskite solar cells is not good. Summary of the Invention

[0004] The technical problem solved by this invention is to further improve the effect of biomolecular additives on the crystallinity and internal defects of perovskites, while ensuring that the additives effectively improve the crystallinity and internal defects of perovskites, thereby enhancing the effect of the additives on uncoordinated Pb at the grain boundaries of perovskites. 2+The passivation effect of Pb cluster defects effectively improves the thin film quality of the perovskite light-absorbing layer, reduces non-radiative recombination sites and photogenerated carrier losses, thereby further enhancing the performance of perovskite solar cells.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A perovskite solar cell using *Tetrandrine* alkaloids as additives includes a perovskite light-absorbing layer, wherein the perovskite light-absorbing layer contains additives selected from at least one of *Tetrandrine*, fangchinorline, and berberine.

[0007] Preferably, the perovskite solar cell with *Euphorbia lathyris* alkaloids as additives further includes a conductive substrate, a tin oxide electron transport layer, a Spiro-OMeTAD hole transport layer, and an electrode layer, wherein the conductive substrate, the tin oxide electron transport layer, the perovskite light-absorbing layer, the Spiro-OMeTAD hole transport layer, and the electrode layer are arranged sequentially from bottom to top.

[0008] Preferably, the perovskite solar cell with *Euphorbia lathyris* alkaloids as additives further includes a conductive substrate, a SAM hole transport layer, a PCBM electron transport layer, a BCP electron modification layer, and an electrode layer, wherein the conductive substrate, the SAM hole transport layer, the perovskite light-absorbing layer, the PCBM electron transport layer, the BCP electron modification layer, and the electrode layer are arranged sequentially from bottom to top.

[0009] This invention also provides a method for preparing a perovskite solar cell using *Euphorbia lathyris* alkaloids as an additive, as described above, comprising the following steps:

[0010] Step S1: After cleaning and drying the conductive substrate and treating it with ultraviolet ozone, spin-coating tin oxide solution onto the conductive substrate and annealing it to obtain a tin oxide electron transport layer.

[0011] Step S2: Additives are incorporated into the perovskite precursor solution, heated and stirred to obtain a perovskite precursor solution containing additives; the perovskite precursor solution containing additives is spin-coated onto the tin oxide electron transport layer and annealed to obtain a perovskite light-absorbing layer.

[0012] Step S3: Spin-coat Spiro-OMeTAD solution onto the perovskite light-absorbing layer to obtain a Spiro-OMeTAD hole transport layer;

[0013] Step S4: Add an electrode layer to the Spiro-OMeTAD hole transport layer to obtain a perovskite solar cell.

[0014] Preferably, in step S2, the additive is styrax, and the doping amount of the additive in the perovskite precursor solution containing the additive is 0.1-2.5 mg / mL.

[0015] Preferably, in step S2, the perovskite precursor solution comprises a perovskite material and a precursor solvent, wherein the perovskite material comprises methylamine lead bromide and formamidin lead iodine.

[0016] Preferably, in step S3, a cobalt salt is added to the Spiro-OMeTAD solution.

[0017] Preferably, in step S1, the annealing temperature is 150-180℃ and the annealing time is 10-30 minutes.

[0018] Preferably, in step S2, an antisolvent is added dropwise during the spin-coating of the perovskite precursor solution containing the additive onto the tin oxide electron transport layer.

[0019] This invention also provides a method for preparing a perovskite solar cell using *Euphorbia lathyris* alkaloids as an additive, as described above, comprising the following steps:

[0020] Step M1: After cleaning and drying the conductive substrate and treating it with ultraviolet ozone, spin-coating the SAM solution onto the conductive substrate and annealing it to obtain the SAM hole transport layer.

[0021] Step M2: Additives are incorporated into the perovskite precursor solution, heated and stirred to obtain a perovskite precursor solution containing additives; the perovskite precursor solution containing additives is spin-coated onto the SAM hole transport layer and annealed to obtain a perovskite light-absorbing layer.

[0022] Step M3: Spin-coat PCBM solution onto the perovskite light-absorbing layer and anneal it to obtain the PCBM electron transport layer;

[0023] Step M4: Spin-coat BCP solution onto the PCBM electron transport layer and anneal it to obtain the BCP electron modification layer;

[0024] Step M5: Add an electrode layer to the BCP electronic modification layer to obtain a perovskite solar cell.

[0025] The perovskite solar cell using *Tetrandrine* alkaloids as additives provided by this invention has the advantage over existing technologies in that it dops the perovskite light-absorbing layer with *Tetrandrine*, fangchinorline, or berberine. The oxygen in the molecular structures of *Tetrandrine*, fangchinorline, and berberine interacts with the perovskite component elements, effectively passivating uncoordinated Pb in the perovskite light-absorbing layer. 2+By eliminating Pb cluster defects, reducing photogenerated carrier losses in perovskite solar cells, and improving the morphology and crystallinity of the perovskite film, the photoelectric conversion efficiency of perovskite solar cells is effectively enhanced. Compared with perovskite solar cells without doping with berberine, fangchinorline, or berberine, the perovskite light-absorbing layer in this invention has higher film quality, and the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the perovskite solar cell are significantly increased. Furthermore, the berberine alkaloids used as additives are derived from natural products, are non-toxic, and environmentally friendly. Compared with other biomolecular additives used in the prior art, berberine, fangchinorline, or berberine, as additives, can effectively passivate internal defects in perovskite crystals. Due to their larger molecular size, relatively few of these additives enter the perovskite crystal lattice, with most molecules accumulating at the grain boundaries, thus more effectively passivating uncoordinated Pb at the grain boundaries. 2+ The removal of Pb cluster defects further reduces the loss of photogenerated carriers in perovskite solar cells, while also improving the photoelectric conversion efficiency and operational stability of perovskite solar cells, which is more conducive to improving the performance of perovskite solar cells. Attached Figure Description

[0026] Figure 1 This is a process flow diagram for preparing positive perovskite solar cells in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of a positive perovskite solar cell in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of the inverted perovskite solar cell in an embodiment of the present invention;

[0029] Figure 4 The JV curves are shown for the positive perovskite solar cells of Examples 1, 4-8 and Comparative Example 1 in this invention.

[0030] Figure 5 The PL spectra of the perovskite absorbing layers of Example 1 and Comparative Example 1 of this invention are shown.

[0031] Figure 6 These are SEM images of the perovskite light-absorbing layers of Example 1 and Comparative Example 1 of the present invention.

[0032] Figure 7 The images show the AFM images of the perovskite light-absorbing layers of Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] It should be noted that, unless otherwise specified, the features in the embodiments of this invention can be combined with each other. The terms "comprising," "including," "containing," and "having" are non-limiting, meaning that other steps and other components that do not affect the results can be added. The above terms cover the terms "composed of" and "substantially composed of." Unless otherwise specified, the materials, equipment, and reagents are commercially available.

[0035] This invention provides a perovskite solar cell using *Lysimachia* alkaloids as additives, comprising a perovskite light-absorbing layer. The perovskite light-absorbing layer contains additives selected from at least one of *Lysimachia* alkaloids, fangchinorline, and berberine. *Lysimachia* alkaloids, fangchinorline, and berberine are all *Lysimachia* alkaloids.

[0036] The perovskite solar cell using *Tetrandrine* alkaloids as additives provided by this invention has the advantage over existing technologies in that it dops the perovskite light-absorbing layer with *Tetrandrine*, fangchinorline, or berberine. The oxygen in the molecular structure of these substances interacts with the perovskite components, effectively passivating uncoordinated Pb in the perovskite light-absorbing layer. 2+ By eliminating Pb cluster defects, reducing photogenerated carrier losses in perovskite solar cells, and improving the morphology and crystallinity of the perovskite film, the photoelectric conversion efficiency of perovskite solar cells is effectively enhanced. Compared with perovskite solar cells without doping with berberine, fangchinorline, or berberine, the perovskite light-absorbing layer in the perovskite solar cell using berberine alkaloids as additives in this invention has higher film quality, and the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the perovskite solar cell are significantly increased. Furthermore, the additive materials used are derived from natural products, are non-toxic, and environmentally friendly. Compared with other biomolecular additives used in existing technologies, berberine, fangchinorline, or berberine, as additives, can effectively passivate internal defects in perovskite crystals. However, due to their larger molecular size, relatively fewer molecules of these additives enter the perovskite crystal lattice, with most molecules accumulating at the grain boundaries, thus more effectively passivating uncoordinated Pb at the grain boundaries. 2+The removal of Pb cluster defects further reduces photogenerated carrier losses in perovskite solar cells, while simultaneously improving their photoelectric conversion efficiency and operational stability, thus enhancing their overall performance. In existing technologies, additives doped into the perovskite absorber layer primarily utilize the electronegativity of oxygen, chlorine, and nitrogen atoms. Enhanced electronegativity strengthens intermolecular chemical bonds, resulting in better passivation. The berberine, tetrandrine, or berberine used in this invention primarily utilize the electronegativity of oxygen atoms. Oxygen atoms are more electronegative than chlorine and nitrogen atoms, thus effectively removing uncoordinated Pb from the perovskite absorber layer. 2+ It has a better passivation effect on Pb cluster defects.

[0037] In this invention, there are two types of perovskite solar cells using *Euphorbia lathyris* alkaloids as additives: one is a positive perovskite solar cell containing the aforementioned perovskite light-absorbing layer, and the other is an inverse perovskite solar cell containing the aforementioned perovskite light-absorbing layer. For example, as... Figure 2 As shown, the positive perovskite solar cell comprises, from bottom to top, a conductive substrate, a tin oxide electron transport layer, a perovskite light-absorbing layer, a 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD) hole transport layer, and an electrode layer. Exemplarily, as... Figure 3 As shown, the inverted perovskite solar cell comprises, from bottom to top, a conductive substrate, a self-assembled monolayer (SAM) hole transport layer, a perovskite light-absorbing layer, an [6,6]-phenyl-C61-butyrate isomethyl ester (PCBM) electron transport layer, a 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline (BCP) electron modification layer, and an electrode layer.

[0038] like Figure 1 As shown, this embodiment of the invention provides a method for fabricating the above-mentioned positive perovskite solar cell, comprising the following steps:

[0039] Step S1: After cleaning and drying the conductive substrate and treating it with ultraviolet ozone, spin-coating tin oxide solution onto the conductive substrate and annealing it to obtain a tin oxide electron transport layer.

[0040] Step S2: Additives are incorporated into the perovskite precursor solution, heated and stirred to obtain a perovskite precursor solution containing additives; the perovskite precursor solution containing additives is spin-coated onto the tin oxide electron transport layer and annealed to obtain a perovskite light-absorbing layer.

[0041] Step S3: Spin-coat Spiro-OMeTAD solution onto the perovskite light-absorbing layer to obtain a Spiro-OMeTAD hole transport layer;

[0042] Step S4: Add an electrode layer to the Spiro-OMeTAD hole transport layer to obtain a perovskite solar cell.

[0043] In the method for preparing a positive perovskite solar cell in this embodiment of the invention, alkaloids such as berberine, tetrandrine, or berberine are doped into the perovskite light-absorbing layer of the perovskite solar cell. The interaction between the oxygen in the molecular structure of these alkaloids and the perovskite component elements effectively passivates the uncoordinated Pb in the perovskite light-absorbing layer. 2+ By eliminating Pb cluster defects, the photogenerated carrier loss in perovskite solar cells is reduced, the morphology and crystallinity of the perovskite film are improved, and the photoelectric conversion efficiency of perovskite solar cells is effectively enhanced.

[0044] In an embodiment of the present invention, after spin-coating the tin oxide solution onto the conductive substrate in step S1, a further annealing treatment is required. The annealing temperature is 150-180°C, and the annealing time is 10-30 minutes. Since the electron transport layer solution contains water, high-temperature annealing is necessary to rapidly evaporate the water and promote crystal crystallization, forming a smooth and dense electron transport layer. Therefore, an annealing treatment of 10-30 minutes at 150-180°C is chosen.

[0045] Preferably, in step S2, the additive is styrax, and the doping amount of styrax in the perovskite precursor solution containing the additive is 0.1-2.5 mg / mL. Styrax is readily soluble in N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solutions. The doping amount of styrax is controlled at 0.1-2.5 mg / mL to ensure that the styrax passivates the uncoordinated Pb in the perovskite light-absorbing layer. 2+ While mitigating the effects of Pb cluster defects, it does not affect the spreadability of the perovskite precursor solution on the electron transport layer surface, nor does it inhibit the spread of the Spiro-OMeTAD solution on the perovskite layer surface. This ensures that the addition of styrax tinctoria does not adversely affect the electron transport layer and hole transport layer, and ensures that the prepared perovskite solar cell has high open-circuit voltage, current density, fill factor and photoelectric conversion efficiency.

[0046] In embodiments of the present invention, during step S2, when doping the additive into the perovskite precursor solution, the precursor solution needs to be heated and stirred. The heating temperature is 25-70°C, and the stirring time is 15-60 minutes. Stirring the perovskite precursor solution containing the additive for an appropriate time at an appropriate temperature ensures that the additive is completely dissolved in the perovskite precursor solution.

[0047] In an embodiment of the present invention, in step S2, the perovskite precursor solution containing additives is spin-coated onto the tin oxide electron transport layer. Further annealing of the perovskite light-absorbing layer is required. The annealing temperature is 100-150°C, and the annealing time is 30-60 minutes. Annealing at 100-150°C is selected based on the phase transition temperature of the perovskite material.

[0048] In an embodiment of the present invention, in step S2, the perovskite precursor solution comprises perovskite material and a precursor solvent, wherein the perovskite material comprises methylamine lead bromide and formamidinium lead iodide. Compared to perovskite material containing pure formamidinium lead iodide, perovskite material containing methylamine lead bromide and formamidinium lead iodide has a wider band gap due to the introduction of bromine atoms and methylamine ions, which is beneficial for improving the open-circuit voltage. Furthermore, wide band gap perovskites are also suitable for fabricating tandem solar cells, providing more options for fabricating high-efficiency cells. In addition, bromide ions help improve the humidity stability of formamidinium lead iodide, which is beneficial for fabricating perovskite solar cells with better stability.

[0049] In an embodiment of the present invention, in step S2, during the spin-coating of the perovskite precursor solution containing additives onto the tin oxide electron transport layer, an antisolvent is added dropwise. The antisolvent is selected from at least one of diethyl ether, ethyl acetate, chlorobenzene, and anisole. Adding the antisolvent dropwise during the spin-coating of the perovskite light-absorbing layer facilitates the rapid evaporation of the solvent in the precursor solution, thereby accelerating nucleation and crystal growth. This promotes the formation of the black phase in the perovskite crystal and improves the thin film quality, ultimately enhancing the overall performance and air stability of the perovskite solar cell.

[0050] In an embodiment of the present invention, the preparation process of the Spiro-OMeTAD solution in step S3 is as follows: 520 mg Li-TFSI is dissolved in 1 mL acetonitrile to prepare a Li salt solution; 300 mg FK209 Co(III)TFSI is dissolved in 1 mL acetonitrile to prepare a Co salt solution; subsequently, 65-100 mg Spiro-OMe TAD, 30 μL 4-TBP, 18 μL Li salt solution and 10 μL Co salt solution are dissolved in 1 mL chlorobenzene solution to prepare the Spiro-OMe TAD solution.

[0051] The preparation process of the Spiro-OMeTAD solution shows that the prepared Spiro-OMeTAD solution contains Co salt, therefore the Spiro-OMeTAD hole transport layer also contains Co salt. Thus, the Co-based Spiro-OMeTAD hole transport layer can generate [Spiro-OMeTAD]. +The cobalt salt in the hole transport layer of Spiro-OMeTAD can protect the perovskite light-absorbing layer, thereby reducing the adverse effects of commonly used additives such as lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and tributyl phosphate (TBP), thus reducing the concentration of recombination sites; the orbital energy level (HOMO level) of CoII / III(dpzpyr)2 is low enough to thermodynamically prevent hole trapping; Co salt doping also helps to shorten the oxidation time in the fabrication process of positive perovskite solar cell devices.

[0052] In an embodiment of the present invention, in step S2, the perovskite precursor solution containing additives is spin-coated onto the tin oxide electron transport layer. The specific spin-coating process is as follows: the prepared perovskite precursor solution containing styrax is dropped onto the tin oxide electron transport layer. First, spin-coating is performed at 1000 rpm for 10 seconds, then at 5000 rpm for 30 seconds, and 200 μL of chlorobenzene is added as an antisolvent at the 25th second. In this embodiment of the present invention, the spin-coating of the perovskite precursor solution containing additives onto the tin oxide electron transport layer is carried out in two steps. First, spin-coating is performed at 1000 rpm, as this low-speed spin-coating process facilitates solution spreading. Further increasing the spin-coating speed to 5000 rpm results in a more uniform perovskite light-absorbing layer film. Compared to a one-step spin-coating method, this method produces a higher quality perovskite light-absorbing layer film.

[0053] This invention also provides a method for preparing the above-mentioned inverted perovskite solar cell, comprising the following steps:

[0054] Step M1: After cleaning and drying the conductive substrate and treating it with ultraviolet ozone, spin-coating the SAM solution onto the conductive substrate and annealing it to obtain the SAM hole transport layer.

[0055] Step M2: Additives are incorporated into the perovskite precursor solution, heated and stirred to obtain a perovskite precursor solution containing additives; the perovskite precursor solution containing additives is spin-coated onto the SAM hole transport layer and annealed to obtain a perovskite light-absorbing layer.

[0056] Step M3: Spin-coat PCBM solution onto the perovskite light-absorbing layer and anneal it to obtain the PCBM electron transport layer;

[0057] Step M4: Spin-coat BCP solution onto the PCBM electron transport layer and anneal it to obtain the BCP electron modification layer;

[0058] Step M5: Add an electrode layer to the BCP electronic modification layer to obtain a perovskite solar cell.

[0059] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to the conditions recommended by the manufacturer.

[0060] Example 1

[0061] 1.1 The etched ITO conductive substrate was sequentially ultrasonically cleaned for 30 min each in ultrapure water, ultrapure water, acetone, and isopropanol containing cleaning agents, and then dried with nitrogen. The ITO conductive glass was then treated with ultraviolet ozone for 20 min to obtain a clean ITO conductive substrate. 10 mL of a 15% tin oxide colloidal solution was dissolved in 5 mL of ultrapure water and stirred at room temperature for 2 h to prepare a tin oxide precursor solution. The tin oxide precursor solution was spin-coated onto the ITO conductive substrate at 5000 rpm for 15 s. The ITO substrate coated with the tin oxide solution was annealed at 150 °C for 30 min to obtain a tin oxide electron transport layer.

[0062] 1.2 Prepare a mixed solvent by mixing 900 μL DMF and 100 μL DMSO. Dissolve 0.673 g lead iodide, 0.229 g formamidin iodide, 0.008 g methylammonium bromide and 0.026 g lead bromide in the mixed solvent, and add 0.5 mg of zein as an additive. Stir at 50 °C for 30 min to obtain a perovskite precursor solution containing zein. Take the prepared perovskite precursor solution containing zein and drop it onto the tin oxide electron transport layer. First spin coat at 1000 rpm for 10 s, then spin coat at 5000 rpm for 30 s. At the 25th second, add 200 μL chlorobenzene as an antisolvent. Anneal at 100 °C for 60 min to obtain the perovskite light-absorbing layer.

[0063] 1.3. Dissolve 520 mg Li-TFSI in 1 mL acetonitrile to prepare a Li salt solution; dissolve 300 mg FK 209Co(III)TFSI in 1 mL acetonitrile to prepare a Co salt solution; then dissolve 73 mg Spiro-OMeTAD, 30 μL 4-TBP, 18 μL Li salt solution and 10 μL Co salt solution in 1 mL chlorobenzene solution to prepare a Spiro-OMeTAD solution; drop the prepared Spiro-OMeTAD solution onto the perovskite light-absorbing layer and spin-coat at 4000 rpm for 30 s to obtain the Spiro-OMeTAD hole transport layer.

[0064] 1.4. A 100 nm silver electrode was deposited on the Spiro-OMeTAD hole transport layer using a vacuum thermal evaporation method to obtain a perovskite solar cell.

[0065] Example 2

[0066] 2.1 The etched ITO conductive substrate was sequentially ultrasonically cleaned for 30 min each in ultrapure water, ultrapure water, acetone, and isopropanol containing cleaning agents, and then dried with nitrogen. The ITO conductive glass was then treated with ultraviolet ozone for 20 min to obtain a clean ITO conductive substrate. 10 mL of a 15% tin oxide colloidal solution was dissolved in 5 mL of ultrapure water and stirred at room temperature for 2 h to prepare a tin oxide precursor solution. The tin oxide precursor solution was spin-coated onto the ITO conductive substrate at 5000 rpm for 15 s. The ITO substrate coated with the tin oxide solution was annealed at 165 °C for 20 min to obtain a tin oxide electron transport layer.

[0067] 2.2 Prepare a mixed solvent by mixing 900 μL DMF and 100 μL DMSO. Dissolve 0.673 g lead iodide, 0.229 g formamidin iodide, 0.008 g methylammonium bromide and 0.026 g lead bromide in the mixed solvent, and add 0.5 mg of zein as an additive. Stir at 25 °C for 60 min to obtain a perovskite precursor solution containing zein. Take the prepared perovskite precursor solution containing zein and drop it onto the tin oxide electron transport layer. First spin coat at 1000 rpm for 10 s, then spin coat at 5000 rpm for 30 s. At the 25th second, add 200 μL chlorobenzene as an antisolvent. Anneal at 150 °C for 10 min to obtain the perovskite light-absorbing layer.

[0068] 2.3. 520 mg Li-TFSI was dissolved in 1 mL acetonitrile to prepare a Li salt solution; 300 mg FK 209Co(III)TFSI was dissolved in 1 mL acetonitrile to prepare a Co salt solution; then 100 mg Spiro-OMeTAD, 30 μL 4-TBP, 18 μL Li salt solution and 10 μL Co salt solution were dissolved in 1 mL chlorobenzene solution to prepare a Spiro-OMeTAD solution; the prepared Spiro-OMeTAD solution was dropped onto a perovskite light-absorbing layer and spin-coated at 4000 rpm for 30 s to obtain a Spiro-OMeTAD hole transport layer.

[0069] 2.4. A 100 nm silver electrode was deposited on the Spiro-OMeTAD hole transport layer using a vacuum thermal evaporation method to obtain a perovskite solar cell.

[0070] Example 3

[0071] 3.1 The etched ITO conductive substrate was sequentially ultrasonically cleaned for 30 min each in ultrapure water, ultrapure water, acetone, and isopropanol containing cleaning agent, and then dried with nitrogen. The ITO conductive glass was then treated with ultraviolet ozone for 20 min to obtain a clean ITO conductive substrate. 10 mL of a 15% tin oxide colloidal solution was dissolved in 5 mL of ultrapure water and stirred at room temperature for 2 h to prepare a tin oxide precursor solution. The tin oxide precursor solution was spin-coated onto the ITO conductive substrate at 5000 rpm for 15 s. The ITO substrate coated with the tin oxide solution was annealed at 180 °C for 10 min to obtain a tin oxide electron transport layer.

[0072] 3.2 Prepare a mixed solvent by mixing 900 μL DMF and 100 μL DMSO. Dissolve 0.673 g lead iodide, 0.229 g formamidin iodide, 0.008 g methylammonium bromide and 0.026 g lead bromide in the mixed solvent, and add 0.5 mg of zein as an additive. Stir at 70 °C for 15 min to obtain a perovskite precursor solution containing zein. Take the prepared perovskite precursor solution containing zein and drop it onto the tin oxide electron transport layer. Spin coat at 1000 rpm for 10 s, then spin coat at 5000 rpm for 30 s. Add 200 μL chlorobenzene as an antisolvent at 25 s. Anneal at 125 °C for 45 min to obtain the perovskite light-absorbing layer.

[0073] 3.3 Dissolve 520 mg Li-TFSI in 1 mL acetonitrile to prepare a Li salt solution; dissolve 300 mg FK 209Co(III)TFSI in 1 mL acetonitrile to prepare a Co salt solution; then dissolve 65 mg Spiro-OMeTAD, 30 μL 4-TBP, 18 μL Li salt solution and 10 μL Co salt solution in 1 mL chlorobenzene solution to prepare a Spiro-OMeTAD solution; drop the prepared Spiro-OMeTAD solution onto the perovskite light-absorbing layer and spin-coat at 4000 rpm for 30 s to obtain the Spiro-OMeTAD hole transport layer.

[0074] 3.4. A 100 nm silver electrode was deposited on the Spiro-OMeTAD hole transport layer using a vacuum thermal evaporation method to obtain a perovskite solar cell.

[0075] Example 4

[0076] The difference from Example 1 is that the doping amount of senna is 0.1 mg.

[0077] Example 5

[0078] The difference from Example 1 is that the doping amount of senna is 0.25 mg.

[0079] Example 6

[0080] The difference from Example 1 is that the doping amount of senna is 0.75 mg.

[0081] Example 7

[0082] The difference from Example 1 is that the doping amount of senna is 1 mg.

[0083] Example 8

[0084] The difference from Example 1 is that the doping amount of senna is 2.5 mg.

[0085] Example 9

[0086] 9.1 The etched ITO conductive glass was sequentially ultrasonicated for 30 min each in ultrapure water, ultrapure water, acetone, and isopropanol with added cleaning agent. After drying with nitrogen, it was treated with ultraviolet ozone for 20 min to obtain a clean ITO conductive glass substrate. SAM solution was spin-coated onto the ITO conductive substrate, wherein SAM is [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), the SAM solution concentration is 0.5 mg / ml, the spin-coating speed is 3000 rpm, the spin-coating time is 40 s, and the substrate is annealed at 100℃ for 20 min to obtain the SAM hole transport layer.

[0087] 9.2. Prepare a mixed solvent by mixing 900 μL DMF and 100 μL LDMSO. Dissolve 0.673 g lead iodide, 0.229 g formamidin iodide, 0.008 g methylammonium bromide and 0.026 g lead bromide in the mixed solvent, and add 0.5 mg of zein as an additive. Stir at 25 °C for 60 min to obtain a perovskite precursor solution containing zein. Take the prepared zein-doped perovskite precursor solution and drop it onto the SAM hole transport layer. Spin coat at 1000 rpm for 10 s, then spin coat at 5000 rpm for 30 s. Add 200 μL chlorobenzene as an antisolvent at 25 s. Anneal the substrate coated with the perovskite wet film at 100 °C for 60 min to obtain the perovskite light-absorbing layer.

[0088] 9.3 Prepare a PCBM solution with a concentration of 25 mg / ml, spin-coat the PCBM solution onto the perovskite light-absorbing layer, and anneal at 100℃ for 5 min to obtain the PCBM electron transport layer. The spin-coating speed is 3000 rpm and the spin-coating time is 40 s.

[0089] 9.4 Prepare a BCP solution with a concentration of 0.8 mg / ml, spin-coat the BCP solution onto the PCBM electron transport layer, and anneal at 100℃ for 5 min to obtain a BCP electron-modified layer. The spin-coating speed is 4000 rpm and the spin-coating time is 30 s.

[0090] 9.5. A silver electrode is deposited on the surface of the BCP electronic modification layer to obtain a perovskite solar cell with an electrode thickness of 100 nm.

[0091] Example 10

[0092] The difference from Example 9 is that the additive is fentanyl alkaloid, and the doping amount of fentanyl alkaloid is 0.5 mg.

[0093] Example 11

[0094] The difference from Example 9 is that the additive is berberine, and the doping amount of berberine is 0.5 mg.

[0095] Comparative Example 1

[0096] The difference from Example 1 is that the doping amount of senna is 0.

[0097] Comparative Example 2

[0098] The difference from Example 9 is that the doping amount of senna is 0.

[0099] Experimental Example

[0100] Under standard test conditions (AM 1.5G illumination), the JV characteristics of the positive perovskite solar cells prepared in Examples 1, 4-8, and Comparative Example 1 were tested, and the JV curves were obtained, as shown below. Figure 4 As shown, the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the positive perovskite solar cells prepared in Examples 1, 4-8, and Comparative Example 1 were analyzed, and the data comparison is shown in Table 1. From the above data, it can be seen that the positive perovskite solar cells prepared in Examples 1 and 4-8 of the present invention have higher photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor compared with the positive perovskite solar cell in Comparative Example 1, exhibiting superior performance.

[0101] Table 1. Performance comparison of positive perovskite solar cells prepared in Examples 1, 4-8 and Comparative Example 1.

[0102]

[0103]

[0104] The perovskite absorbing layers prepared in Example 1 and Comparative Example 1 were characterized by PL spectroscopy, SEM, and AFM, respectively. Figure 5 The image shows the PL spectra of the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1. The PL intensity of Example 1 is significantly increased compared to Comparative Example 1, indicating that the chemical interaction between perovskite and styraxin effectively passivates the grain boundary trap states in the perovskite film. Figure 6 These are scanning electron microscope (SEM) images of the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1, wherein... Figure 6 (A) corresponds to Example 1. Figure 6 The response ratio for China (B) is 1, by Figure 6 As can be seen in Figure (B), the perovskite film in Comparative Example 1 contains white crystals (i.e., excess lead iodide). (Comparison) Figure 6 (A) and Figure 6 As can be seen in (B), no white crystals (excess lead iodide) appeared in the perovskite film in Example 1. This is because in Example 1, after the addition of styrax, the excess lead iodide further participated in the perovskite crystallization, thus the lead iodide completely disappeared. This indicates that the perovskite film doped with styrax crystallized more fully and had higher crystal quality. (Comparison) Figure 6 (A) and Figure 6 In Example 1 (B), it can also be seen that the crystal size is more uniform, there are no small holes at the grain boundaries as in Comparative Example 1, the surface of the perovskite film is smoother, and the quality of the perovskite film is higher. Figure 7 Atomic force microscopy (AFM) images of the perovskite absorbing layers prepared in Example 1 and Comparative Example 1, wherein... Figure 7 (A) corresponds to Example 1. Figure 7 China (B) corresponds to a ratio of 1, in comparison. Figure 7 (A) and Figure 7 As can be seen in (B), compared with Comparative Example 1, the surface roughness of the perovskite film in Example 1 is significantly reduced, the film quality is improved, which is beneficial to the improvement of the performance of perovskite solar cells.

[0105] Under standard test conditions (AM 1.5G illumination), the JV characteristics of the inverted perovskite solar cells prepared in Examples 9-11 and Comparative Example 2 of the present invention were tested. The photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of Examples 9-11 and Comparative Example 2 were obtained. The data comparison is shown in Table 2. It can be seen from the data in Table 2 that the inverted perovskite solar cells prepared in Examples 9-11 of the present invention have higher photoelectric conversion efficiency, open-circuit voltage, and fill factor than the inverted perovskite solar cells in Comparative Example 2, and their performance is superior.

[0106] Table 2 Comparison of the performance of inverted perovskite solar cells prepared in Examples 9-11 and Comparative Example 2

[0107] Comparative Example 2 24.73 1.09 79.44 21.50 Example 9 24.35 1.13 81.61 22.48 Example 10 24.82 1.13 81.17 22.78 Example 11 24.99 1.12 81.74 22.81

[0108] In summary, compared with perovskite solar cells without additives, the perovskite light-absorbing layer in the perovskite solar cells using *Euphorbia lathyris* alkaloids as additives in the embodiments of the present invention has improved film quality and crystallinity, improved morphology of the perovskite light-absorbing layer, and significantly increased open-circuit voltage, fill factor, and photoelectric conversion efficiency of the perovskite solar cells.

[0109] Furthermore, it should be noted that although the present invention has been disclosed as described above, the scope of protection of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A perovskite solar cell using *Euphorbia pekinensis* alkaloids as an additive, characterized in that, It includes a perovskite light-absorbing layer, the perovskite light-absorbing layer containing an additive selected from at least one of fentanylamine and berberine.

2. The perovskite solar cell using *Euphorbia lathyris* alkaloids as an additive according to claim 1, characterized in that, It also includes a conductive substrate, a tin oxide electron transport layer, a Spiro-OMeTAD hole transport layer, and an electrode layer, wherein the conductive substrate, the tin oxide electron transport layer, the perovskite light-absorbing layer, the Spiro-OMeTAD hole transport layer, and the electrode layer are arranged sequentially from bottom to top.

3. The perovskite solar cell using *Euphorbia lathyris* alkaloids as an additive according to claim 1, characterized in that, It also includes a conductive substrate, a SAM hole transport layer, a PCBM electron transport layer, a BCP electron modification layer, and an electrode layer, wherein the conductive substrate, the SAM hole transport layer, the perovskite light-absorbing layer, the PCBM electron transport layer, the BCP electron modification layer, and the electrode layer are arranged sequentially from bottom to top.

4. A method for preparing a perovskite solar cell using *Euphorbia lathyris* alkaloids as additives, characterized in that, The method for preparing a perovskite solar cell using *Euphorbia tannin* alkaloids as an additive as described in claim 1 or 2 comprises the following steps: Step S1: After cleaning and drying the conductive substrate and treating it with ultraviolet ozone, spin-coating tin oxide solution onto the conductive substrate and annealing it to obtain a tin oxide electron transport layer. Step S2: Additives are incorporated into the perovskite precursor solution, heated and stirred to obtain a perovskite precursor solution containing additives; the perovskite precursor solution containing additives is spin-coated onto the tin oxide electron transport layer and annealed to obtain a perovskite light-absorbing layer. Step S3: Spin-coat Spiro-OMeTAD solution onto the perovskite light-absorbing layer to obtain a Spiro-OMeTAD hole transport layer; Step S4: Add an electrode layer to the Spiro-OMeTAD hole transport layer to obtain a perovskite solar cell.

5. The method for preparing a perovskite solar cell using *Euphorbia lathyris* alkaloids as an additive according to claim 4, characterized in that, In step S2, the additive is senna extract, and the doping amount of the additive in the perovskite precursor solution containing the additive is 0.1-2.5 mg / mL.

6. The method for preparing a perovskite solar cell using *Cephalotaxus fortunei* alkaloids as an additive according to claim 4, characterized in that, In step S2, the perovskite precursor solution comprises perovskite material and precursor solvent, wherein the perovskite material comprises methylamine lead bromide and formamidin lead iodine.

7. The method for preparing a perovskite solar cell using *Cephalotaxus fortunei* alkaloids as an additive according to claim 4, characterized in that, In step S3, cobalt salt is added to the Spiro-OMeTAD solution.

8. The method for preparing a perovskite solar cell using *Cephalotaxus fortunei* alkaloids as an additive according to claim 4, characterized in that, In step S1, the annealing temperature is 150-180℃ and the annealing time is 10-30 minutes.

9. The method for preparing a perovskite solar cell using *Euphorbia lathyris* alkaloids as an additive according to claim 4, characterized in that, In step S2, during the process of spin-coating the perovskite precursor solution containing additives onto the tin oxide electron transport layer, an antisolvent is added dropwise.

10. A method for preparing a perovskite solar cell using *Euphorbia lathyris* alkaloids as additives, characterized in that, The method for preparing a perovskite solar cell using *Euphorbia tannin* alkaloids as an additive as described in claim 1 or 3 includes the following steps: Step M1: After cleaning and drying the conductive substrate and treating it with ultraviolet ozone, spin-coating the SAM solution onto the conductive substrate and annealing it to obtain the SAM hole transport layer. Step M2: Additives are incorporated into the perovskite precursor solution, heated and stirred to obtain a perovskite precursor solution containing additives; the perovskite precursor solution containing additives is spin-coated onto the SAM hole transport layer and annealed to obtain a perovskite light-absorbing layer. Step M3: Spin-coat PCBM solution onto the perovskite light-absorbing layer and anneal it to obtain the PCBM electron transport layer; Step M4: Spin-coat BCP solution onto the PCBM electron transport layer and anneal it to obtain the BCP electron modification layer; Step M5: Add an electrode layer to the BCP electronic modification layer to obtain a perovskite solar cell.

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