Tin-lead perovskite solar cell based on guanidine sulfide passivator and preparation method of tin-lead perovskite solar cell

Abstract

The invention discloses a tin-lead perovskite solar cell based on a guanidine sulfide passivator and a preparation method of the tin-lead perovskite solar cell, and belongs to the technical field of solar cells. The tin-lead perovskite solar cell based on the guanidine sulfide passivator comprises a conductive substrate, a hole transport layer, a first passivation layer, a tin-lead perovskite absorption layer, a second passivation layer, an electron transport layer, a buffer layer and a metal electrode layer which are sequentially stacked from bottom to top, the hole transport layer is made of poly (3, 4-ethylenedioxythiophene)-poly (styrene sulfonate); the first passivation layer and the second passivation layer are made of guanidine sulfide passivators; and the tin-lead perovskite absorption layer is made of a mixture of a tin-lead perovskite material and a guanidine sulfide passivator. The invention also discloses a preparation method of the tin-lead perovskite solar cell based on the guanidine sulfide passivator. According to the invention, the problems of bulk phase defects and poor interface stability between the hole transport layer and perovskite of the existing tin-lead perovskite solar cell can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and particularly relates to a tin-lead perovskite solar cell based on a guanidine sulfide passivator and a preparation method thereof. Background Art

[0002] Perovskite solar cells have rapidly emerged in recent years and attracted extensive attention from scientists worldwide. The organic-inorganic hybrid perovskite semiconductor material contained therein is the core of perovskite solar cells. These materials not only have excellent light absorption ability and electron migration performance, but also can be prepared by low-temperature processes such as solution method and spraying method, having the advantages of low production cost and suitability for large-scale production. In addition, due to the emergence of the band bending effect, the band gap of tin-lead perovskite solar cells has become the solar cell that can theoretically be closest to the S-Q limit.

[0003] At present, the efficiency of the most efficient tin-lead perovskite solar cells has already broken through the 23% mark; however, further research and breakthroughs are still needed in terms of the stability of the materials and environmental friendliness (especially the lead pollution problem). In recent years, tin-lead perovskite solar cells still face multiple challenges in terms of achieving higher photoelectric conversion efficiency and long-term stability in the bulk phase and at the interface.

[0004] In the bulk material, tin (Sn 2+ ) is easily oxidized to Sn 4+ resulting in a high background hole concentration and uncontrollable p-type doping, which not only exacerbates non-radiative recombination, but also causes lattice distortion and phase separation problems; at the same time, the toxicity limitation of lead (Pb) and the crystallization kinetics of the tin-lead ratio regulation are difficult to balance, and it is easy to form a non-uniform film layer with a dense defect state. In terms of interface problems, the energy level mismatch and chemical interaction between the perovskite and the charge transport layer will induce interface recombination, and the traditional passivation strategy is significantly insufficient for the defects of the tin-lead system; in addition, the ion migration and interface reaction between the metal electrode and the perovskite accelerate the device performance degradation. These bulk phase and interface problems interact with each other, seriously restricting the improvement of device efficiency and the commercialization process, and it is urgent to achieve breakthroughs through component engineering, defect passivation and new interface material design. The traditional methods often optimize the bulk phase or interface in isolation, resulting in limited performance gain; the development of multifunctional materials that can simultaneously regulate the bulk phase and interface characteristics is crucial for promoting the development of tin-lead perovskite solar cells. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a tin-lead perovskite solar cell based on a guanidine sulfide passivator and a preparation method thereof, so as to solve the problems of bulk phase defects existing in the existing tin-lead perovskite solar cells and poor interface stability between the hole transport layer and the perovskite.

[0006] The technical solution adopted to solve its technical problems is to provide a tin-lead perovskite solar cell based on a guanidine thiourea passivator. The tin-lead perovskite solar cell based on a guanidine thiourea passivator includes a conductive substrate, a hole transport layer, a first passivation layer, a tin-lead perovskite absorption layer, a second passivation layer, an electron transport layer, a buffer layer, and a metal electrode layer, which are stacked in sequence from bottom to top; The material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate); the materials of the first passivation layer and the second passivation layer are both guanidine thiourea passivators; the material of the tin-lead perovskite absorption layer is a mixture of tin-lead perovskite material and guanidine thiourea passivator.

[0007] The beneficial effects of the present invention adopting the above technical solution are as follows: The present invention has developed a highly efficient and stable tin-lead perovskite solar cell based on a guanidine thiourea passivator, and through the multi-functional synergistic passivation strategy of the guanidine thiourea passivator, a "triple-in-one" synergistic effect is achieved. First, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), as the most commonly used hole transport layer in tin-based perovskite solar cells, its inherent acidity and hygroscopicity will accelerate the oxidation and degradation of the perovskite structure. In the present invention, the guanidine thiourea passivator forms a unique bifunctional modification layer at the PEDOT:PSS interface. Its guanidine functional group can precisely regulate the work function of PEDOT:PSS to 5.0 - 5.2 eV, achieving an ideal match with the valence band energy level of perovskite; at the same time, the thiourea group in the molecule can selectively neutralize the acidic sites of PEDOT:PSS, reducing the interfacial corrosion rate without affecting conductivity, and realizing the interfacial synergistic regulation effect. Second, the guanidine thiourea passivator realizes the selective hierarchical passivation of perovskite defects through the differentiated functional groups in the molecule: the guanidine group preferentially passivates deep-level defects (>0.3 eV), while the thiourea group mainly passivates shallow-level defects (<0.3 eV). This hierarchical passivation reduces the interfacial state density by one order of magnitude. At the same time, the guanidine thiourea passivator forms a dynamic passivation network in-situ during the perovskite crystallization process, which not only guides the crystal orientation growth but also synchronously passivates new-born defects, increasing the film grain size while reducing the grain boundary defect density, realizing the crystallization-passivation synergistic effect; in addition, the guanidine group and thiourea group in the guanidine thiourea passivator molecule respectively form strong coordination bonds with Sn 2+ / Pb 2+ in the perovskite bulk phase, effectively inhibiting Sn 2+ oxidation and passivating deep-level defects; after being modified by the guanidine thiourea passivator, an ordered molecular arrangement is formed at the interface, constructing a low-loss carrier transport path, significantly improving the hole extraction efficiency and reducing the interfacial recombination velocity constant.

[0008] Preferably, the guanidine thiourea passivator is 1-ethyl-3-guanylthiourea hydrochloride.

[0009] Preferably, the material of the conductive substrate is ITO conductive glass; the tin-lead perovskite material in the tin-lead perovskite absorption layer is FA 0.3 MA 0.6 CS 0.1 Sn 0.5 Pb 0.5 I3; the material of the electron transport layer is C 60 ; the material of the buffer layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; the material of the metal electrode layer is copper metal; the thickness of the conductive substrate is 2-4 mm, the thickness of the hole transport layer is 30-50 nm, the thickness of the first passivation layer is 3-6 nm, the thickness of the tin-lead perovskite absorption layer is 650-760 nm, the thickness of the second passivation layer is 4-8 nm, the thickness of the electron transport layer is 20-30 nm, the thickness of the buffer layer is 5-7 nm, and the thickness of the metal electrode layer is 90-110 nm.

[0010] More preferably, the thickness of the conductive substrate is 3 mm, the thickness of the hole transport layer is 40 nm, the thickness of the first passivation layer is 4 nm, the thickness of the tin-lead perovskite absorption layer is 720 nm, the thickness of the second passivation layer is 5 nm, the thickness of the electron transport layer is 25 nm, the thickness of the buffer layer is 6 nm, and the thickness of the metal electrode layer is 100 nm.

[0011] The present invention also provides a method for preparing the above-mentioned tin-lead perovskite solar cell based on the guanidine sulfur passivator, including the following steps: (1) Spin-coat a solution of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) on a pre-cleaned conductive substrate and anneal to obtain a hole transport layer; (2) Dissolve the guanidine sulfur passivator in an organic solvent to obtain a passivation layer solution; (3) Co-dissolve the guanidine sulfur passivator and the raw materials of the tin-lead perovskite material in an organic solvent to obtain a tin-lead perovskite absorption layer solution; (4) Under an inert atmosphere, spin-coat the passivation layer solution onto the hole transport layer and let it stand, then spin-coat the tin-lead perovskite absorption layer solution and anneal to sequentially obtain a first passivation layer and a tin-lead perovskite absorption layer; (5) Spin-coat the passivation layer solution on the tin-lead perovskite absorption layer again and anneal to obtain a second passivation layer; (6) Use vacuum thermal evaporation deposition to sequentially deposit an electron transport layer, a buffer layer, and a metal electrode layer on the surface of the second passivation layer, and then perform encapsulation to obtain the product.

[0012] Preferably, in step (1), the spin-coating speed is 4000-6000 rpm, and the time is 20-40 s; the annealing temperature is 100-200 °C, and the time is 15-30 min.

[0013] More preferably, in step (1), the spin coating speed is 5000 rpm and the time is 30 s; the annealing temperature is 150 °C and the time is 20 min.

[0014] Preferably, in step (2), the organic solvent is a mixed solution of toluene and isopropyl alcohol mixed at a volume ratio of 1~2:1~2; the mass concentration of the passivation layer solution is 0.2~0.4 mg / mL.

[0015] More preferably, in step (2), the organic solvent is a mixed solution of toluene and isopropyl alcohol mixed at a volume ratio of 1:1; the mass concentration of the passivation layer solution is 0.375 mg / mL.

[0016] Preferably, in step (3), the organic solvent is a mixed solution of dimethyl sulfoxide and N,N-dimethylformamide mixed at a volume ratio of 1:(2~3); the raw materials of the tin-lead perovskite material include NH4SCN, GlyHCl, SnF2, CsI, MAI, FAI, SnI2 and PbI2; the mass ratio of the guanidine thiocyanate passivator to SnI2 in the raw materials of the tin-lead perovskite material is (0.1~0.5):100.

[0017] More preferably, in step (3), the organic solvent is a mixed solution of dimethyl sulfoxide and N,N-dimethylformamide mixed at a volume ratio of 1:3; the mass ratio of the guanidine thiocyanate passivator to SnI2 in the raw materials of the tin-lead perovskite material is 0.224:100.

[0018] More preferably, the mass ratio of NH4SCN, GlyHCl and SnI2 is (0.5~2):(0.5~2):100.

[0019] More preferably, the mass ratio of NH4SCN, GlyHCl and SnI2 is 0.817:1.199:100.

[0020] Preferably, in step (4), the rotation speed of spin coating the passivation layer solution is 3000~5000 rpm and the time is 10~30 s; the standing time is 1~3 min; spin coating the tin-lead perovskite absorption layer solution and annealing includes the following steps: accelerating the tin-lead perovskite absorption layer solution from 200~400 rpm to 1000~1400 rpm at an acceleration of 200~400 rpm for the first spin coating for 5~15 s, annealing at 90~110 °C for 6~8 min, then accelerating from 900~1100 rpm to 4000~5000 rpm at an acceleration of 900~1100 rpm for the second spin coating for 45~55 s, dropping chlorobenzene at the 15th s of the second spin coating, and annealing at 60~70 °C for 7~9 min after the second spin coating ends.

[0021] More preferably, in step (4), the rotation speed of spin-coating the passivation layer solution is 4000 rpm, and the time is 20 s; the standing time is 2 min; spin-coating the tin-lead perovskite absorption layer solution and annealing include the following steps: accelerating the tin-lead perovskite absorption layer solution to 1200 rpm at an acceleration of 300 rpm for the first spin-coating for 10 s, annealing at 100 °C for 7 min, then accelerating to 4500 rpm at an acceleration of 1000 rpm for the second spin-coating for 50 s, dropping chlorobenzene at the 15th s of the second spin-coating, and annealing at 65 °C for 8 min after the second spin-coating ends.

[0022] More preferably, in step (5), the spin-coating speed is 4000 - 6000 rpm, and the time is 20 - 40 s; the annealing temperature is 90 - 110 °C, and the time is 4 - 6 min; the volume ratio of the passivation layer solutions in step (4) and step (5) is (7 - 9):(10 - 11).

[0023] More preferably, in step (5), the spin-coating speed is 5000 rpm, and the time is 30 s; the annealing temperature is 100 °C, and the time is 5 min; the volume ratio of the passivation layer solutions in step (4) and step (5) is 8:10.

[0024] Preferably, in step (6), the vacuum degree of the vacuum thermal evaporation deposition method is 4×10 -4 ~6×10 -4 Pa, and the deposition rate is 0.1 - 0.2 Å.

[0025] More preferably, in step (6), the vacuum degree of the vacuum thermal evaporation deposition method is 5×10 -4 Pa, and the deposition rate is 0.1 Å.

[0026] The present invention has the following beneficial effects: (1) In the tin-lead perovskite solar cell prepared by the present invention based on the guanidinium thiocyanate passivator, the guanidinium thiocyanate passivator is used to synergistically passivate the hole transport layer / perovskite absorption layer interface, the perovskite absorption layer bulk phase, and the perovskite absorption layer / electron transport layer interface, realizing the synergistic effects of bulk phase defect passivation, interface stability improvement, and carrier transport enhancement, effectively solving the problems of bulk phase defects and poor interface stability existing in the existing tin-lead perovskite solar cells; (2) The tin-lead perovskite solar cell prepared by the present invention based on the guanidinium thiocyanate passivator has good photoelectric conversion efficiency, open circuit voltage, short circuit current, and fill factor. It has less loss in the process of converting light energy into electrical energy, high overall energy conversion efficiency, and good performance stability during long-term operation. Description of the Drawings

[0027] Figure 1It is a structural diagram of a tin-lead perovskite solar cell device; among them, (a) is the tin-lead perovskite solar cell of Comparative Example 1; (b) is the tin-lead perovskite solar cell based on guanidine sulfur passivator of Example 1. Figure 2 It is a comparison chart of the photoelectric conversion efficiency of the tin-lead perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 3 It is a comparison chart of the open-circuit voltage of the tin-lead perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 4 It is a comparison chart of the short-circuit current of the tin-lead perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 5 It is a comparison chart of the fill factor of the tin-lead perovskite solar cells prepared in Example 1 and Comparative Example 1. Figure 6 It is for the tin-lead perovskite solar cells prepared in Example 1 and Comparative Example 1 J-V curve graph. Detailed implementation manners

[0028] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained by purchasing in the market. 1-Ethyl-3-guanylthiourea hydrochloride is from Macklin Reagent with a purity of 98%. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution is from Heraeus with the specification of PVP AI 4083.

[0029] Example 1 A tin-lead perovskite solar cell based on guanidine sulfur passivator, including a conductive substrate made of ITO conductive glass with a thickness of 3 mm, a hole transport layer made of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) with a thickness of 40 nm, a first passivation layer made of 1-ethyl-3-guanylthiourea hydrochloride with a thickness of 4 nm, a tin-lead perovskite absorption layer with a thickness of 720 nm, a second passivation layer made of 1-ethyl-3-guanylthiourea hydrochloride with a thickness of 5 nm, a material of C 60 and an electron transport layer with a thickness of 25 nm, a buffer layer made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with a thickness of 6 nm and a metal electrode layer made of copper metal with a thickness of 100 nm; Among them, the material of the tin-lead perovskite absorption layer is FA 0.3 MA 0.6 CS 0.1Sn 0.5 Pb 0.5 A mixture of I3 and 1-ethyl-3-guanylthiourea hydrochloride.

[0030] The device structure of a tin-lead perovskite solar cell based on a guanidine sulfur passivator is as Figure 1 (b) shown.

[0031] In this embodiment, a method for preparing a tin-lead perovskite solar cell based on a guanidine sulfur passivator is also provided, including the following steps: (1) Place the ITO conductive glass with a preset pattern sputtered by laser into a cleaning rack, wash it with deionized water and glass cleaning solution for 1 h, and then rinse it with deionized water until the glass cleaning solution on its surface is completely removed; then place the ITO conductive glass in deionized water and absolute ethanol in turn for 2 ultrasonic treatments, each treatment for 15 min, and then dry it with a nitrogen gun and put it into an ultraviolet-ozone machine for ozone treatment for 15 min to obtain a pre-cleaned conductive substrate; (2) Use a medical sterile syringe to suck 1 mL of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution, and then use a filter head to evenly coat the pre-cleaned conductive substrate, and spin-coat it at a speed of 5000 rpm for 30 s. After the spin-coating is completed, anneal it on a heating table at 150 °C for 20 min to obtain a hole transport layer; (3) Weigh 0.75 mg of 1-ethyl-3-guanylthiourea hydrochloride and add it to a 2 mL mixed solution of toluene and isopropanol mixed in a volume ratio of 1:1, and then place it in a shaker for shaking and dissolving for 3 h to obtain a colorless passivation layer solution with a mass concentration of 0.375 mg / mL; (4) Weigh 0.75 mg of 1-ethyl-3-guanylthiourea hydrochloride, 2.74 mg of NH4SCN, 4.02 mg of GlyHCl, 14.10 mg of SnF2, 46.77 mg of CsI, 85.84 mg of MAI, 185.73 mg of FAI, 335.27 mg of SnI2 and 484.91 mg of PbI2 in a glove box filled with nitrogen, mix them and add them to a 1 mL mixed solution of dimethyl sulfoxide and N,N-dimethylformamide mixed in a volume ratio of 1:3, and then place it in a shaker for shaking and dissolving for 3 h to obtain a light yellow tin-lead perovskite absorption layer solution; (5) Place the conductive substrate with a hole transport layer prepared in step (2) stably in a petri dish and transfer it into a nitrogen glove box; under a nitrogen atmosphere, spin-coat 80 μL of the passivation layer solution on the surface of the hole transport layer at a speed of 4000 rpm for 20 s, and let it stand for 2 min; then accelerate 70 μL of the tin-lead perovskite absorber layer solution from 300 rpm to 1200 rpm for the first spin-coating for 10 s, anneal at 100 °C for 7 min, and then accelerate from 1000 rpm to 4500 rpm for the second spin-coating for 50 s. At the 15th s of the second spin-coating, add 600 μL of chlorobenzene, and after the second spin-coating is completed, anneal at 65 °C for 8 min to successively prepare the first passivation layer and the tin-lead perovskite absorber layer; (6) Spin-coat 100 μL of the passivation layer solution on the tin-lead perovskite absorber layer again at a speed of 5000 rpm for 30 s and anneal at 100 °C for 5 min to obtain the second passivation layer; (7) Place the conductive substrate with the second passivation layer prepared in step (6) into a container. After the evaporation equipment is filled with gas, place the container on the mask plate and then transfer it to the evaporation equipment. Use a mechanical pump and a molecular pump to reduce the vacuum degree in the chamber to 5×10 -4 Pa, then slowly heat it up at an average rate of 20 °C / min. When the deposition rate reaches 0.1 Å and stabilizes, open the baffle, and appropriately adjust according to the evaporation thickness and sequentially evaporate C 60 , 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline and copper metal; after the device preparation is completed, use UV curable glue to bond the encapsulation glass and the solar cell device in the glove box to obtain it.

[0032] Example 2 A tin-lead perovskite solar cell based on a guanidine sulfur passivator has the same structure and materials as in Example 1.

[0033] In this example, a preparation method of a tin-lead perovskite solar cell based on a guanidine sulfur passivator is also provided, including the following steps: (1) Place the ITO conductive glass with a preset pattern sputtered by laser into a cleaning rack, clean it with deionized water and glass cleaning solution for 1 h, and then rinse it with deionized water until the glass cleaning solution on its surface is completely removed; then place the ITO conductive glass in deionized water and absolute ethanol respectively for 2 times of ultrasonic treatment, each treatment for 15 min, then blow it dry with a nitrogen gun and put it into an ultraviolet-ozone machine for ozone treatment for 15 min to obtain a pre-cleaned conductive substrate; (2) Use a medical sterile syringe to aspirate 1 mL of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution, and then use a filter head to evenly coat it on a pre-cleaned conductive substrate, and spin-coat it at a speed of 4000 rpm for 40 s. After spin-coating, place it on a heating table at 100 °C and anneal it for 30 min to obtain a hole transport layer; (3) Weigh 0.4 mg of 1-ethyl-3-guanylthiourea hydrochloride and add it to a mixed solution of 2 mL of toluene and isopropanol mixed in a volume ratio of 2:1, and then place it in a shaker and shake it for 3 h to dissolve it, obtaining a colorless passivation layer solution with a mass concentration of 0.2 mg / mL; (4) Respectively weigh 0.34 mg of 1-ethyl-3-guanylthiourea hydrochloride, 1.68 mg of NH4SCN, 1.68 mg of GlyHCl, 14.10 mg of SnF2, 46.77 mg of CsI, 85.84 mg of MAI, 185.73 mg of FAI, 335.27 mg of SnI2 and 484.91 mg of PbI2 in a glove box filled with nitrogen, mix them and add them to a mixed solution of 1 mL of dimethyl sulfoxide and N,N-dimethylformamide mixed in a volume ratio of 1:3, and then place it in a shaker and shake it for 3 h to dissolve it, obtaining a light yellow tin-lead perovskite absorption layer solution; (5) Place the conductive substrate with the hole transport layer prepared in step (2) stably in a petri dish and transfer it to a nitrogen glove box; under a nitrogen atmosphere, spin-coat 80 μL of the passivation layer solution on the surface of the hole transport layer at a speed of 3000 rpm for 30 s, and let it stand for 1 min; then spin-coat 70 μL of the tin-lead perovskite absorption layer solution at an acceleration of 200 rpm to 1000 rpm for the first spin-coating for 5 s, perform annealing at 90 °C for 8 min, and then spin-coat it at an acceleration of 900 rpm to 4000 rpm for the second spin-coating for 45 s. At the 15th s of the second spin-coating, add 600 μL of chlorobenzene, and perform annealing at 60 °C for 9 min after the second spin-coating to sequentially obtain a first passivation layer and a tin-lead perovskite absorption layer; (6) Spin-coat 100 μL of the passivation layer solution on the tin-lead perovskite absorption layer again at a speed of 4000 rpm for 20 s and anneal it at 90 °C for 6 min to obtain a second passivation layer; (7) Place the conductive substrate with the second passivation layer prepared in step (6) into a container. After the evaporation equipment is filled with gas, place its container on the mask plate and then transfer it to the evaporation equipment. Use a mechanical pump and a molecular pump to reduce the vacuum degree in the chamber to 4×10 -4Pa, and then slowly heat it up at an average rate of 20 °C / min. After the deposition rate reaches 0.1 Å and stabilizes, open the baffle, and appropriately adjust according to the evaporation thickness and evaporate C, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and copper metal in sequence; after the device is prepared, use UV curable glue to bond the encapsulation glass to the solar cell device in a glove box to obtain the product. 60 、2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and copper metal; after the device is prepared, use UV curable glue to bond the encapsulation glass to the solar cell device in a glove box to obtain the product.

[0034] Example 3 A tin-lead perovskite solar cell based on guanidine sulfur passivator, whose structure and materials are the same as those in Example 1.

[0035] In this example, a preparation method of a tin-lead perovskite solar cell based on guanidine sulfur passivator is also provided, including the following steps: (1) Place the ITO conductive glass with a preset pattern sputtered by laser into a cleaning rack, clean it with deionized water and glass cleaning solution for 1 h, and then rinse it with deionized water until the glass cleaning solution on its surface is completely removed; then place the ITO conductive glass in deionized water and absolute ethanol respectively for 2 times of ultrasonic treatment, each treatment for 15 min, then dry it with a nitrogen gun and put it into an ultraviolet-ozone machine for ozone treatment for 15 min to obtain a pre-cleaned conductive substrate; (2) Use a medical sterile syringe to suck 1 mL of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution, and then use a filter head to evenly coat the pre-cleaned conductive substrate, and spin-coat it at a speed of 6000 rpm for 20 s. After the spin-coating is completed, place it on a heating table at 200 °C for annealing for 15 min to obtain a hole transport layer; (3) Weigh 0.8 mg of 1-ethyl-3-guanidinium thiourea hydrochloride and add it to a 2 mL mixed solution of toluene and isopropanol mixed at a volume ratio of 1:2, and then place it in a shaker for shaking and dissolving for 3 h to obtain a colorless passivation layer solution with a mass concentration of 0.4 mg / mL; (4) Weigh 0.75 mg of 1-ethyl-3-guanidinium thiourea hydrochloride, 6.7 mg of NH4SCN, 6.7 mg of GlyHCl, 14.10 mg of SnF2, 46.77 mg of CsI, 85.84 mg of MAI, 185.73 mg of FAI, 335.27 mg of SnI2, and 484.91 mg of PbI2 respectively in a glove box filled with nitrogen and add them to a 1 mL mixed solution of dimethyl sulfoxide and N,N-dimethylformamide mixed at a volume ratio of 1:3, and then place it in a shaker for shaking and dissolving for 3 h to obtain a light yellow tin-lead perovskite absorption layer solution; (5) Place the conductive substrate with a hole transport layer prepared in step (2) steadily in a petri dish and transfer it into a nitrogen glove box. Under a nitrogen atmosphere, spin-coat 80 μL of the passivation layer solution on the surface of the hole transport layer at a speed of 5000 rpm for 10 s, and let it stand for 3 min. Then, accelerate 70 μL of the tin-lead perovskite absorption layer solution from 400 rpm to 1400 rpm for the first spin-coating for 15 s, anneal at 110 °C for 6 min, and then accelerate from 1100 rpm to 5000 rpm for the second spin-coating for 55 s. At the 15th s of the second spin-coating, add 600 μL of chlorobenzene, and after the second spin-coating is completed, anneal at 70 °C for 7 min to obtain the first passivation layer and the tin-lead perovskite absorption layer in sequence. (6) Spin-coat 100 μL of the passivation layer solution on the tin-lead perovskite absorption layer again at a speed of 6000 rpm for 40 s and anneal at 110 °C for 4 min to obtain the second passivation layer. (7) Place the conductive substrate with the second passivation layer prepared in step (6) into a container. After the evaporation equipment is filled with gas, place the container on the mask plate and then transfer it into the evaporation equipment. Use a mechanical pump and a molecular pump to reduce the vacuum degree in the chamber to 6×10 -4 Pa, and then slowly heat it up at an average rate of 20 °C / min. When the deposition rate reaches 0.1 Å and stabilizes, open the baffle, and appropriately adjust according to the evaporation thickness and evaporate C 60 , 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline and copper metal in sequence. After the device preparation is completed, use UV curable glue to bond the encapsulation glass and the solar cell device in the glove box to obtain the product.

[0036] Comparative Example 1 A tin-lead perovskite solar cell, comprising a conductive substrate made of ITO conductive glass with a thickness of 3 nm, a hole transport layer made of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) with a thickness of 40 nm, a tin-lead perovskite absorption layer with a thickness of 720 nm, an electron transport layer made of C 60 with a thickness of 25 nm, a buffer layer made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with a thickness of 6 nm, and a metal electrode layer made of copper metal with a thickness of 100 nm; Among them, the material of the tin-lead perovskite absorption layer is FA 0.3 MA 0.6 CS 0.1 Sn 0.5 Pb 0.5 I3.

[0037] The device structure of the tin-lead perovskite solar cell is as Figure 1 (a) shown.

[0038] In this comparative example, a preparation method of a tin-lead perovskite solar cell is also provided, including the following steps: (1) Place the ITO conductive glass with a preset pattern sputtered by laser into a cleaning rack, clean it with deionized water and glass cleaning solution for 1 h, and then rinse it with deionized water until the glass cleaning solution on its surface is completely removed; then place the ITO conductive glass in deionized water and anhydrous ethanol respectively for 2 times of ultrasonic treatment, 15 min each time, then dry it with a nitrogen gun and put it into an ultraviolet-ozone machine for ozone treatment for 15 min to obtain a pre-cleaned conductive substrate; (2) Use a medical sterile syringe to suck 1 mL of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution, and then use a filter head to evenly coat the pre-cleaned conductive substrate, and spin-coat it at a speed of 5000 rpm for 30 s. After the spin-coating is completed, anneal it on a heating table at 150 °C for 20 min to obtain a hole transport layer; (3) Weigh 2.74 mg of NH4SCN, 4.02 mg of GlyHCl, 14.10 mg of SnF2, 46.77 mg of CsI, 85.84 mg of MAI, 185.73 mg of FAI, 335.27 mg of SnI2 and 484.91 mg of PbI2 respectively in a glove box filled with nitrogen, mix them and add them to a mixed solution of 1 mL of dimethyl sulfoxide and N,N-dimethylformamide mixed in a volume ratio of 1:3, and then place it in a shaker for 3 h of shaking dissolution to obtain a tin-lead perovskite absorption layer solution; (4) Place the conductive substrate with the hole transport layer prepared in step (2) stably in a petri dish and transfer it into a nitrogen glove box; under a nitrogen atmosphere, spin-coat 70 μL of the tin-lead perovskite absorption layer solution on the surface of the hole transport layer at an acceleration of 300 rpm to 1200 rpm for the first time for 30 s, anneal at 100 °C for 7 min, and then spin-coat at an acceleration of 1000 rpm to 4500 rpm for the second time for 50 s. Drop 600 μL of chlorobenzene at the 15th s of the second spin-coating. After the second spin-coating is completed, anneal at 65 °C for 8 min to obtain a tin-lead perovskite absorption layer; (5) Place the conductive substrate with the tin-lead perovskite absorption layer prepared in step (4) into a container. After the evaporation equipment is inflated, place its container on the mask plate and then transfer it into the evaporation equipment. Use a mechanical pump and a molecular pump to reduce the vacuum degree in the chamber to 5×10 -4Pa, and then slowly heated at an average rate of 20 °C / min. After the deposition rate reached 0.1 Å and stabilized, the shutter was opened, and C was evaporated in sequence after appropriate adjustment according to the evaporation thickness. 60 , 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and copper metal; after the device was prepared, the encapsulation glass was bonded to the solar cell device with UV curable glue in a glove box, and thus obtained.

[0039] Experimental Example The tin-lead perovskite solar cells prepared in Example 1 and Comparative Example 1 were tested. The specific method was as follows: 20 sets of tin-lead perovskite solar cell devices of Example 1 and 20 sets of Comparative Example 1 were prepared using the same preparation means; in a glove box filled with nitrogen, a Keysight B2901A source meter was used to measure J-V the curve, and the scanning speed and holding time were 0.08 V / s and 100 ms respectively. In the solar cell test, a mask with an area of 0.0576 cm -2 was used; the light source for testing the battery was calibrated using an Enli Tech (SRC-00331) silicon standard cell and a (SS-F5) solar simulator to simulate AM 1.5G sunlight; for long-term stability, all test equipment was encapsulated with UV curable agent and encapsulation glass sheets, and all test data were measured under N2 atmosphere at room temperature; after the test, the optoelectronic parameters of 20 sets of devices were counted, and the test results were as Figures 2 to 6 shown.

[0040] From Figures 2 to 5 it can be seen that for the tin-lead perovskite solar cell based on guanidine sulfur passivator prepared in Example 1 of the present invention, its photoelectric conversion efficiency, open circuit voltage, short circuit current, and fill factor have all been significantly improved. The tin-lead perovskite solar cell treated with 1-ethyl-3-guanidinium thiocyanate hydrochloride (EGH) is significantly better than the tin-lead perovskite solar cell prepared in Comparative Example 1. From Figure 6 it can be seen that at the same voltage, the tin-lead perovskite solar cell based on guanidine sulfur passivator prepared in Example 1 of the present invention has a higher current density than the tin-lead perovskite solar cell prepared in Comparative Document 1. This indicates that the interface of the tin-lead perovskite solar cell based on sulfur passivator has been optimized. By passivating defects and increasing the carrier transport ability, the open circuit voltage and short circuit current of the solar cell are respectively improved, and finally a high conversion efficiency is achieved.

[0041] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of the present invention.

Claims

1. A tin-lead perovskite solar cell based on a guanidine sulfur passivator, characterized in that, The guanidine thiocyanate passivator-based tin-lead perovskite solar cell includes a conductive substrate, a hole transport layer, a first passivation layer, a tin-lead perovskite absorption layer, a second passivation layer, an electron transport layer, a buffer layer, and a metal electrode layer, which are stacked in sequence from bottom to top; The material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate); the materials of the first passivation layer and the second passivation layer are both guanidine thiocyanate passivator; the material of the tin-lead perovskite absorption layer is a mixture of tin-lead perovskite material and guanidine thiocyanate passivator.

2. The tin-lead perovskite solar cell based on the guanidine sulfur passivator according to claim 1, wherein, The guanidine thiocyanate passivator is 1-ethyl-3-guanylthiourea hydrochloride.

3. The tin-lead perovskite solar cell based on guanidine sulfur passivator according to claim 1, characterized in that, The material of the conductive substrate is ITO conductive glass; the tin-lead perovskite material in the tin-lead perovskite absorption layer is FA 0.3 MA 0.6 CS 0.1 Sn 0.5 Pb 0.5 I3; the material of the electron transport layer is C 60 ; the material of the buffer layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; the material of the metal electrode layer is copper metal; the thickness of the conductive substrate is 2 - 4 mm, the thickness of the hole transport layer is 30 - 50 nm, the thickness of the first passivation layer is 3 - 6 nm, the thickness of the tin-lead perovskite absorption layer is 650 - 760 nm, the thickness of the second passivation layer is 4 - 8 nm, the thickness of the electron transport layer is 20 - 30 nm, the thickness of the buffer layer is 5 - 7 nm, and the thickness of the metal electrode layer is 90 - 110 nm.

4. The preparation method of the tin-lead perovskite solar cell based on a guanidine sulfur passivator according to any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Spin-coat a poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) solution on a pre-cleaned conductive substrate and anneal to obtain a hole transport layer; (2) Dissolve the guanidine thiocyanate passivator in an organic solvent to obtain a passivation layer solution; (3) Co-dissolve the raw materials of the guanidine thiocyanate passivator and the tin-lead perovskite material in an organic solvent to obtain a tin-lead perovskite absorption layer solution; (4) Under an inert atmosphere, spin-coat the passivation layer solution onto the hole transport layer and let it stand, then spin-coat the tin-lead perovskite absorption layer solution and anneal to sequentially obtain the first passivation layer and the tin-lead perovskite absorption layer; (5) Spin-coat the passivation layer solution on the tin-lead perovskite absorption layer again and anneal to obtain the second passivation layer; (6) Use vacuum thermal evaporation deposition method to sequentially deposit an electron transport layer, a buffer layer, and a metal electrode layer on the surface of the second passivation layer, and then perform encapsulation to obtain the product.

5. The preparation method of the tin-lead perovskite solar cell based on the guanidine thiocyanate passivator according to claim 4, characterized in that, In the step (1), the spin-coating speed is 4000 - 6000 rpm, and the time is 20 - 40 s; the annealing temperature is 100 - 200 °C, and the time is 15 - 30 min.

6. The preparation method of the tin-lead perovskite solar cell based on a guanidine sulfur passivator according to claim 4, characterized in that, In the step (2), the organic solvent is a mixed solution of toluene and isopropyl alcohol with a volume ratio of 1 - 2:1 - 2; the mass concentration of the passivation layer solution is 0.2 - 0.4 mg / mL.

7. The preparation method of the tin-lead perovskite solar cell based on the guanidine thiocyanate passivator according to claim 4, wherein, In the step (3), the organic solvent is a mixed solution of dimethyl sulfoxide and N,N-dimethylformamide with a volume ratio of 1:(2 - 3); the raw materials of the tin-lead perovskite material include NH4SCN, GlyHCl, SnF2, CsI, MAI, FAI, SnI2, and PbI2; the mass ratio of the guanidine thiocyanate passivator to SnI2 in the raw materials of the tin-lead perovskite material is (0.1 - 0.5):

100.

8. The preparation method of the tin-lead perovskite solar cell based on the guanidine sulfur passivator according to claim 4, characterized in that, In the step (4), the rotation speed of spin-coating the passivation layer solution is 3000 - 5000 rpm, and the time is 10 - 30 s; the standing time is 1 - 3 min; the spin-coating of the tin-lead perovskite absorption layer solution and annealing include the following steps: Accelerate the tin-lead perovskite absorption layer solution from 200 - 400 rpm to 1000 - 1400 rpm with an acceleration rate for the first spin-coating for 5 - 15 s, anneal at 90 - 110 °C for 6 - 8 min, then accelerate from 900 - 1100 rpm to 4000 - 5000 rpm with an acceleration rate for the second spin-coating for 45 - 55 s, add chlorobenzene at the 15th s of the second spin-coating, and anneal at 60 - 70 °C for 7 - 9 min after the second spin-coating ends.

9. The preparation method of the tin-lead perovskite solar cell based on guanidine thiocyanate passivator according to claim 4 or 8, characterized in that, In the step (5), the spin coating speed is 4000 - 6000 rpm and the time is 20 - 40 s; the annealing temperature is 90 - 110 °C and the time is 4 - 6 min; in the step (4) and the step (5), the volume ratio of the passivation layer solution is (7 - 9):(10 - 11).

10. The preparation method of the tin-lead perovskite solar cell based on guanidine thiocyanate passivator according to claim 4, characterized in that, In the step (6), the vacuum degree of the vacuum thermal evaporation deposition method is 4×10 -4 ~6×10 -4 Pa, and the deposition rate is 0.1~0.2 Å for both.

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