Preparation method of passivated inorganic perovskite solar cell based on S-(2-aminoethyl) isothiourea bromide onium hydrobromide field

Abstract

A preparation method for passivating an inorganic perovskite solar cell based on an S-(2-aminoethyl) isothiourea bromine onium hydrobromide field is characterized in that S-(2-aminoethyl) isothiourea bromine onium hydrobromide is used as a passivation material to be applied to the surface of an inorganic perovskite thin film, and a uniform passivation layer is formed on the surface of perovskite; the electric field distribution between the perovskite layer and the electron transport layer is significantly improved, the separation and transport of carriers are promoted, and non-radiative recombination is inhibited. Amino groups and thiourea groups in S-(2-aminoethyl) isothiourea bromine onium hydrobromide molecules can form stable coordinate bonds with uncoordinated lead ions on the surface of perovskite, so that the S-(2-aminoethyl) isothiourea bromine onium hydrobromide molecules are effectively anchored on the surface. Meanwhile, bromine ions in the S-(2-aminoethyl) isothiourea bromide onium hydrobromide can fill halogen vacancies in perovskite crystal lattices, so that the defect density is further reduced. And the interface characteristic between the perovskite and the electron transport layer is obviously improved, so that the photoelectric conversion efficiency and the stability of the cell are improved.

Description

Technical Field

[0001] The invention belongs to the field of new energy, and specifically relates to a preparation method of an inorganic perovskite solar cell based on S-(2-aminoethyl)isothiourea bromonium hydrobromide field passivation. Background Art

[0002] With the increasing use of fossil fuels, the environmental problems facing mankind are becoming increasingly prominent. Solar energy resources can continue to last for 60 billion years, which is inexhaustible for the existence of mankind. The excellent photoelectric conversion efficiency and low manufacturing cost of perovskite have made it one of the most popular research hotspots. As a major category of perovskite solar cells, inorganic perovskite solar cells have more advantages than organic-inorganic hybrid perovskite solar cells in terms of long-term operating stability. However, there is a large gap between the photoelectric conversion efficiency (PCE) of inorganic perovskite solar cells and that of organic-inorganic hybrid perovskite solar cells. One of the key factors is the large opening voltage loss of inorganic perovskite cells, which is mainly attributed to the following aspects:

[0003] 1. High defect density: Lead halide vacancies, interstitial atoms and other defects are easily formed in inorganic perovskite crystals. These defects act as non-radiative recombination centers, greatly reducing the carrier lifetime and causing voltage loss.

[0004] 2. Interface recombination: The interface energy levels between the inorganic perovskite and the charge transport layer are mismatched or the interface state density is high, causing the carriers to recombine at the interface instead of being effectively extracted.

[0005] 3. Band structure limitation: Some inorganic perovskites have wide band gaps, but the actual open circuit voltage is affected by non-ideal factors and cannot reach the theoretical limit. In addition, non-ideal band arrangement may lead to low charge extraction efficiency.

[0006] 4. Preparation process challenges: The high-temperature preparation process may introduce grain boundary and surface defects. The defect state density is higher than that of organic-inorganic hybrid perovskite, which aggravates non-radiative recombination.

[0007] In addition, inorganic perovskite films also have the following problems: the large difference in thermal expansion coefficients between the substrate and the perovskite during the annealing process leads to compressive stress in the perovskite, and the higher annealing temperature of the inorganic perovskite leads to greater thermal stress. The presence of stress can lead to lattice distortion and defects, thereby accelerating the decomposition of the perovskite. Solar cells are prone to decomposition under high humidity working conditions.

[0008] In summary, the problems existing in existing inorganic perovskite solar cells are mainly severe open-circuit voltage loss and poor humidity stability. Summary of the invention

[0009] The object of the present invention is to overcome the above-mentioned deficiencies existing in the prior art, and to provide a preparation method of an inorganic perovskite solar cell based on S-(2-aminoethyl)isothiouronium bromide hydrobromide for field passivation.

[0010] To achieve the object of the present invention, the present invention proposes to spin-coat an S-(2-aminoethyl)isothiouronium bromide hydrobromide passivation molecule on the surface of a perovskite film. The sulfur element and amino group in one end of the molecule have strong interaction forces with lead in the inorganic perovskite and are anchored on the perovskite surface. This end is the negative end, and the other end amino group is exposed on the surface layer. This end is the positive end, which accelerates the extraction of charges. It also has a certain surface reconstruction effect, improves the crystallinity of the perovskite surface layer grains and the film quality, effectively passivates the defects of the perovskite grain boundaries, reduces non-radiative recombination, promotes the effective transport of carriers, and obtains a higher open-circuit voltage.

[0011] The technical solution of the present invention is as follows:

[0012] A preparation method of an upper interface passivation layer of an inorganic perovskite solar cell, spin-coating a molecular solution with a certain concentration statically on the perovskite surface; the molecule is S-(2-aminoethyl)isothiouronium bromide hydrobromide; the concentration of the molecular solution is 0.5-1.0 mg / mL.

[0013] A preparation method of an inorganic perovskite solar cell based on S-(2-aminoethyl)isothiouronium bromide hydrobromide for field passivation, the method comprising:

[0014] (1) Cleaning a transparent conductive substrate and preparing a hole transport layer on the transparent conductive substrate;

[0015] (2) Spin-coating an inorganic perovskite precursor solution on the hole transport layer and annealing to prepare a perovskite absorption layer;

[0016] (3) Spin-coating a passivation solution containing S-(2-aminoethyl)isothiouronium bromide hydrobromide molecules on the perovskite absorption layer and annealing to prepare an upper interface passivation layer;

[0017] (4) Preparing an electron transport layer on the upper interface passivation layer;

[0018] (5) Preparing a metal electrode on the electron transport layer;

[0019] Wherein the upper interface passivation layer is prepared by the method described above in the present invention.

[0020] The transparent conductive substrate described in step (1) is one of FTO and ITO conductive glasses;

[0021] The hole transport layer described in step (1) is one of NiO x , SAM, and PTAA;

[0022] The solvent of the perovskite precursor solution described in step (2) is a mixed solution of dimethylformamide and dimethyl sulfoxide, and the solute is inorganic perovskite; the concentration of the solute is 0.6 - 0.8 mol / L; the volume ratio of dimethylformamide to dimethyl sulfoxide is 1:1.

[0023] The perovskite absorption layer described in step (2) is prepared by spin-coating the perovskite precursor solution followed by annealing. The spin-coating speed is 3000 - 5000 rpm / min, and the time is 90 - 110 s; the annealing conditions are annealing at 180 - 200 °C in ambient air for 10 - 15 min.

[0024] The solvent of the upper interface passivation agent solution described in step (3) is a mixed solution of isopropanol:ethanol = 1:1, and the concentration is 0.5 - 1.0 mg / mL.

[0025] The upper interface passivation layer described in step (3) is obtained by static spin-coating the upper interface passivation agent solution and annealing at 70 - 90 °C for 5 - 10 min. The spin-coating speed is 3000 - 5000 rpm / min, and the time is 30 - 50 s.

[0026] The electron transport layer described in step (4) is one of PCBM, SnO2, C 60 among them;

[0027] The metal electrode described in step (5) is a metal wire or metal grid line of silver, copper, or gold deposited by vacuum evaporation with a thickness of 80 - 100 nm.

[0028] The preparation method of the S-(2-aminoethyl)isothiouronium hydrobromide field-passivated inorganic perovskite solar cell of the present invention is not only applicable to inorganic perovskite, but also applicable to organic-inorganic hybrid perovskite and crystalline silicon / perovskite tandem solar cells. The light-absorbing layer prepared by this method can be applied to the following structural devices:

[0029] a. Inorganic perovskite single-junction solar cell;

[0030] b. Hybrid perovskite single-junction solar cell;

[0031] c. Inorganic perovskite / tin-lead perovskite tandem solar cell;

[0032] d. Inorganic perovskite / crystalline silicon tandem solar cell;

[0033] e. Hybrid perovskite / crystalline silicon tandem solar cell.

[0034] The advantages and positive effects of the present invention are:

[0035] The core innovation of the present invention lies in utilizing the unique molecular structure of S-(2-aminoethyl)isothiouronium hydrobromide to achieve field-effect passivation of inorganic perovskite thin films through its multifunctional functional groups, thereby significantly improving the performance and stability of perovskite solar cells. The following is a detailed elaboration of the focus and technical details of the present invention:

[0036] 1. Enhancement of field-effect passivation. ① One end binds and the other end is exposed: The amino (-NH2) functional group and S element at one end of the molecule can form stable and strong coordination bonds with the uncoordinated Pb 2 + defects on the perovskite surface, thus tightly binding, and the other end is exposed on the surface to form a molecular dipole layer. This structure can generate an internal electric field on the perovskite surface, optimize the separation and transport of carriers, and inhibit non-radiative recombination, thereby enhancing the field passivation effect. ② Increase in molecular dipole moment: The sulfur (S) and amino (-NH2) functional groups in the molecule have high electronegativity, increasing the molecular dipole moment and further enhancing the field passivation effect.

[0037] 2. Improvement of stability. The abundant -NH2 and -NH functional groups in the molecule provide more hydrogen bond formation sites, enabling the construction of a stable hydrogen bond network on the perovskite surface. This hydrogen bond network not only enhances the mechanical stability of the passivation layer but also further inhibits ion migration and the generation of defects, thereby improving the overall stability of the device. The bromide ions (Br-) in the molecule can fill the halogen vacancies in the perovskite lattice, thus improving the overall stability of the device.

[0038] 3. Improvement of photoelectric conversion efficiency: Through the synergistic effect of field-effect passivation and chemical passivation, this molecule significantly reduces the surface defect density of the perovskite thin film, optimizes the carrier transport and separation efficiency, and thus greatly improves the photoelectric conversion efficiency of the battery.

[0039] The technology of the present invention is not only applicable to wide and narrow-bandgap inorganic perovskite solar cells but also effective in wide and narrow-bandgap organic-inorganic hybrid cells and perovskite / silicon tandem solar cells. It can also be extended to other perovskite optoelectronic devices such as perovskite light-emitting diodes (PeLEDs) and perovskite photodetectors. The low cost and high efficiency of this technology make it have broad application prospects in large-scale commercial production. Description of the Drawings

[0040] Figure 1 is a schematic structural diagram of the inorganic perovskite solar cell of the present invention;

[0041] Figure 2 is a schematic process diagram of the preparation method of the passivated inorganic perovskite-based solar cell of the present invention;

[0042] Figure 3 is a schematic process diagram of the preparation method of the passivation layer of the present invention;

[0043] Figure 4 is the volt - ampere characteristic curve of the inorganic perovskite solar cell with the upper surface of perovskite passivated by S-(2 - aminoethyl)isothiouronium bromide hydrobromide passivator at a concentration of 0.5 mg / mL in the specific embodiment of the present invention;

[0044] Figure 5 is the volt - ampere characteristic curve of the inorganic perovskite solar cell with the upper surface of perovskite passivated by S-(2 - aminoethyl)isothiouronium bromide hydrobromide passivator at a concentration of 0.75 mg / mL in the specific embodiment of the present invention;

[0045] Figure 6 is the volt - ampere characteristic curve of the inorganic perovskite solar cell with the upper surface of perovskite passivated by S-(2 - aminoethyl)isothiouronium bromide hydrobromide passivator at a concentration of 1.0 mg / mL in the specific embodiment of the present invention;

[0046] Figure 7 is the structural schematic diagram of the inorganic perovskite solar cell without modification by S-(2 - aminoethyl)isothiouronium bromide hydrobromide passivator in the comparative embodiment of the present invention;

[0047] Figure 8 is the volt - ampere characteristic curve of the inorganic perovskite solar cell without modification by S-(2 - aminoethyl)isothiouronium bromide hydrobromide passivator in the comparative embodiment of the present invention; Specific Embodiment

[0048] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] The present invention provides a preparation method of an inorganic perovskite solar cell based on S-(2 - aminoethyl)isothiouronium bromide hydrobromide field passivation; using S-(2 - aminoethyl)isothiouronium bromide hydrobromide to perform surface reconstruction on the perovskite surface, while playing a role in field passivation, effectively improving the efficiency and stability of the perovskite solar cell. The cell structure is stacked from bottom to top in sequence as a transparent conductive substrate, a hole - transporting layer, a perovskite absorption layer, an upper - interface passivation layer, an electron - transporting layer, and a metal electrode.

[0050] A preparation method of an inorganic perovskite solar cell based on S-(2 - aminoethyl)isothiouronium bromide hydrobromide field passivation of the present invention includes the following steps:

[0051] (1) Prepare a hole - transporting layer on the transparent conductive substrate;

[0052] (2) The inorganic perovskite CsPbI 3-x Br xThe precursor solution is spin-coated on the hole transport layer, and after annealing, a perovskite absorption layer is prepared, with a thickness of 300 nm - 800 nm;

[0053] (3) Spin-coat a passivation solution containing S-(2-aminoethyl)isothiouronium bromide hydrobromide molecules on the perovskite absorption layer, and after annealing, prepare an upper interface passivation layer;

[0054] (4) Prepare an electron transport layer on the upper interface passivation layer;

[0055] (5) Prepare a metal electrode on the electron transport layer.

[0056] In the present invention, the upper interface passivation layer is prepared by spin-coating and annealing a passivating agent solution. The spin-coating speed is 3000 - 5000 rpm / min, and the time is 30 - 50 s; the annealing conditions are: annealing at 70 - 90 °C for 5 - 10 min in a nitrogen environment. The concentration of the upper interface passivation layer molecular solution is 0.5 - 1.0 mg / mL, and the solvent of the molecular solution is a mixed solution of isopropanol:ethanol = 1:1.

[0057] In the present invention, the perovskite absorption layer is prepared by spin-coating and annealing a perovskite precursor solution. The spin-coating speed is 3000 - 5000 rpm / min, and the time is 90 - 110 s; the annealing conditions are annealing at 180 - 200 °C for 10 - 15 min in ambient air. The concentration of the perovskite precursor solution is 0.6 - 0.8 mol / L, the solvent is a mixed solution of dimethylformamide and dimethyl sulfoxide, and the solute is inorganic perovskite. The volume ratio of dimethylformamide to dimethyl sulfoxide is 1:1.

[0058] Example 1:

[0059] The present invention provides a method for preparing an S-(2-aminoethyl)isothiouronium bromide hydrobromide field-passivated inorganic perovskite solar cell, comprising the following steps:

[0060] 1. Ultrasonically clean an ITO conductive glass substrate (2×2 cm 2 ) successively with detergent, deionized water, and isopropanol for 15 - 20 min, dry the moisture with nitrogen, and subject the substrate to ultraviolet ozone treatment for 20 - 30 min to obtain a clean and well-wettable ITO conductive glass substrate;

[0061] 2. Add 10 - 30 mg of NiO x powder to 1 mL of deionized water to obtain a 10 - 30 mg / mL NiO x colloidal solution;

[0062] 3. Take the NiO in step 2 xThe colloidal solution was spin-coated on the ITO conductive glass substrate in Step 1 at a rotational speed of 2000 - 3000 rpm / min for a spin-coating time of 20 - 30 s; then, it was annealed at 100 - 130 °C in ambient air for 15 - 30 min; a hole transport layer was prepared.

[0063] 4. Dissolve CsI, HPbI3, and PbBr2 in a mixed solution of dimethylformamide and dimethyl sulfoxide with a volume ratio of 1:1 in a molar ratio of 3.00:2.85:0.15. Then, heat and stir it in a nitrogen environment until completely dissolved to obtain a perovskite precursor solution with a concentration of 0.6 - 0.8 mol / L.

[0064] 5. Take the perovskite solution obtained in Step 4 and spin-coat it on the hole transport layer obtained in Step 3 at a rotational speed of 3000 - 5000 rpm / min for a spin-coating time of 90 - 110 s; anneal it at 180 - 200 °C in ambient air for 10 - 15 min; a perovskite absorption layer was prepared.

[0065] 6. Add 0.5 mg of S-(2-aminoethyl)isothiouronium bromide hydrobromide to 1 mL of a solvent (ethanol:isopropanol = 1:1) to prepare an upper interface passivation solution with a concentration of 0.5 mg / mL.

[0066] 7. Take the upper interface passivation solution obtained in Step 6 and spin-coat it on the perovskite absorption layer obtained in Step 5 at a rotational speed of 3000 - 5000 rpm / min for a spin-coating time of 30 - 50 s; then anneal it in a nitrogen environment at 70 - 90 °C for 5 - 10 min.

[0067] 8. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution; 9. Use a one-step spin-coating method to spin-coat the electron transport layer precursor solution obtained in Step 8 on the upper interface passivation layer prepared in Step 7 at a spin-coating speed of 3000 - 5000 rpm / min for a spin-coating time of 30 - 50 s to prepare an electron transport layer.

[0068] 10. Evaporate an 80 - 100 nm thick silver film on the electron transport layer in Step 9 to obtain an inorganic perovskite solar cell.

[0069] Experimental results: Perform performance tests on the solar cell, as Figure 4 shown. Under illumination with a standard light intensity of AM1.5, 100 mW / cm 2 the open-circuit voltage of the solar cell prepared in this example is 1.205 V, the short-circuit current density is 19.50 mA / cm 2 , the fill factor is 83.97%, and the efficiency is 19.72%.

[0070] Example 2:

[0071] Provided is a preparation method of an inorganic perovskite solar cell based on S-(2-aminoethyl)isothiouronium bromide hydrobromide for field passivation, comprising the following steps:

[0072] 1. Ultrasonically clean an ITO conductive glass substrate (2×2 cm 2 ) successively with a detergent, deionized water, and isopropanol for 15 - 20 min, dry the moisture with nitrogen, and subject the substrate to ultraviolet ozone treatment for 20 - 30 min to obtain a clean ITO conductive glass substrate with good wettability;

[0073] 2. Add 10 - 30 mg of NiO x powder to 1 mL of deionized water to obtain a NiO x colloidal solution with a concentration of 10 - 30 mg / mL;

[0074] 3. Spin - coat the NiO x colloidal solution in step 2 on the ITO conductive glass substrate in step 1 at a rotation speed of 2000 - 3000 rpm / min for a spin - coating time of 20 - 30 s; then, anneal at 100 - 130 °C in ambient air for 15 - 30 min; prepare a hole - transporting layer;

[0075] 4. Dissolve CsI, HPbI3, and PbBr2 in a mixed solution of dimethylformamide and dimethyl sulfoxide with a volume ratio of 1:1 at a molar ratio of 3.00:2.85:0.15. Then, heat and stir in a nitrogen environment until completely dissolved to obtain a perovskite precursor solution with a concentration of 0.6 - 0.8 mol / L;

[0076] 5. Spin - coat the perovskite solution obtained in step 4 on the hole - transporting layer obtained in step 3 at a rotation speed of 3000 - 5000 rpm / min for a spin - coating time of 90 - 110 s; anneal at 180 - 200 °C in ambient air for 10 - 15 min; prepare a perovskite absorption layer;

[0077] 6. Add 0.75 mg of S-(2 - aminoethyl)isothiouronium bromide hydrobromide to 1 mL of a solvent (ethanol:isopropanol = 1:1) to prepare an upper - interface passivation solution with a concentration of 0.75 mg / mL.

[0078] 7. Spin - coat the upper - interface passivation solution obtained in step 6 on the perovskite absorption layer obtained in step 5 at a rotation speed of 3000 - 5000 rpm / min for a spin - coating time of 30 - 50 s; then anneal at 70 - 90 °C in a nitrogen environment for 5 - 10 min.

[0079] 8. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution. 9. Spin-coat the electron transport layer precursor solution obtained in step 8 on the upper interface passivation layer prepared in step 7 by one-step spin-coating method, with a spin-coating speed of 3000 - 5000 rpm / min and a spin-coating time of 30 - 50 s to prepare an electron transport layer.

[0080] 10. Evaporate an 80 - 100 nm thick silver film on the electron transport layer in step 9 to obtain an inorganic perovskite solar cell.

[0081] Experimental results: Perform performance tests on the solar cell, as Figure 5 shown. Under the illumination of standard light intensity of AM1.5, 100 mW / cm 2 , the open-circuit voltage of the solar cell prepared in this example is 1.245 V, the short-circuit current density is 19.69 mA / cm 2 , the fill factor is 84.83%, and the efficiency is 20.80%.

[0082] Example 3:

[0083] Provide a preparation method of an S-(2-aminoethyl)isothiouronium hydrobromide field-passivated inorganic perovskite solar cell, including the following steps:

[0084] 1. Ultrasonically clean the ITO conductive glass substrate (2×2 cm 2 ) with detergent, deionized water, and isopropanol in sequence for 15 - 20 min, dry the moisture with nitrogen, and subject the substrate to ultraviolet ozone treatment for 20 - 30 min to obtain a clean and well-wettable ITO conductive glass substrate;

[0085] 2. Add 10 - 30 mg of NiO x powder to 1 mL of deionized water to obtain a 10 - 30 mg / mL NiO x colloidal solution;

[0086] 3. Take the NiO x colloidal solution in step 2 and spin-coat it on the ITO conductive glass substrate in step 1 at a speed of 2000 - 3000 rpm / min for 20 - 30 s; then, anneal it at 100 - 130 °C in ambient air for 15 - 30 min; prepare a hole transport layer;

[0087] 4. Dissolve CsI, HPbI3, and PbBr2 in a mixed solution of dimethylformamide and dimethyl sulfoxide with a volume ratio of 1:1 at a molar ratio of 3.00:2.85:0.15. Then, heat and stir in a nitrogen environment until completely dissolved to obtain a perovskite precursor solution with a concentration of 0.6 - 0.8 mol / L;

[0088] 5. Spin-coat the perovskite solution obtained in step 4 on the hole transport layer obtained in step 3 at a rotation speed of 3000 - 5000 rpm / min for 90 - 110 s; anneal at 180 - 200 °C for 10 - 15 min in ambient air; prepare the perovskite absorption layer.

[0089] 6. Add 1.0 mg of S-(2-aminoethyl)isothiouronium bromide hydrobromide to 1 mL of solvent (ethanol:isopropanol = 1:1) to prepare an upper interface passivation solution with a concentration of 1.0 mg / mL.

[0090] 7. Spin-coat the upper interface passivation solution obtained in step 6 on the perovskite absorption layer obtained in step 5 at a rotation speed of 3000 - 5000 rpm / min for 30 - 50 s; then anneal at 70 - 90 °C for 5 - 10 min in a nitrogen environment.

[0091] 8. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution; 9. Use a one-step spin-coating method to spin-coat the electron transport layer precursor solution obtained in step 8 on the upper interface passivation layer prepared in step 7 at a spin-coating speed of 3000 - 5000 rpm / min for 30 - 50 s to prepare an electron transport layer.

[0092] 10. Evaporate an 80 - 100 nm thick silver film on the electron transport layer in step 9 to obtain an inorganic perovskite solar cell.

[0093] Experimental results: Perform performance tests on the solar cell, as Figure 6 shown. Under the illumination of AM1.5, 100 mW / cm 2 standard light intensity, the open-circuit voltage of the solar cell prepared in this example is 1.211 V, the short-circuit current density is 19.13 mA / cm 2 , the fill factor is 77.71%, and the efficiency is 18.00%.

[0094] Comparative example:

[0095] The present invention provides an inorganic solar cell field-free passivation enhancement technology and its preparation method, including the following steps:

[0096] 1. Ultrasonically clean the ITO conductive glass substrate (2 × 2 cm 2 ) with detergent, deionized water, and isopropanol in sequence for 15 - 20 min, dry the moisture with nitrogen, and subject the substrate to ultraviolet ozone treatment for 20 - 30 min to obtain a clean and well-wettable ITO conductive glass substrate.

[0097] 2. Add 10 - 30 mg of NiO xThe powder was added to 1 mL of deionized water to obtain a NiO colloidal solution with a concentration of 10 - 30 mg / mL. x Colloidal solution;

[0098] 3. The NiO colloidal solution in step 2 was spin-coated on the ITO conductive glass substrate in step 1 at a rotation speed of 2000 - 3000 rpm / min for 20 - 30 s. Then, it was annealed at 100 - 130 °C in ambient air for 15 - 30 min to prepare a hole transport layer. x Colloidal solution was spin-coated on the ITO conductive glass substrate in step 1 at a rotation speed of 2000 - 3000 rpm / min for 20 - 30 s. Then, it was annealed at 100 - 130 °C in ambient air for 15 - 30 min to prepare a hole transport layer.

[0099] 4. CsI, HPbI3, and PbBr2 were dissolved in a mixed solution of dimethylformamide and dimethyl sulfoxide with a volume ratio of 1:1 in a molar ratio of 3.00:2.85:0.15. Then, it was heated and stirred in a nitrogen environment until completely dissolved to obtain a perovskite precursor solution with a concentration of 0.6 - 0.8 mol / L.

[0100] 5. The perovskite solution obtained in step 4 was spin-coated on the hole transport layer obtained in step 3 at a rotation speed of 3000 - 5000 rpm / min for 90 - 110 s. Then, it was annealed at 180 - 200 °C in ambient air for 10 - 15 min to prepare a perovskite absorption layer.

[0101] 6. PCBM powder was added to chlorobenzene and stirred until completely dissolved to obtain an electron transport layer solution.

[0102] 7. The electron transport layer precursor solution obtained in step 6 was spin-coated on the perovskite absorption layer prepared in step 5 by one-step spin coating at a rotation speed of 3000 - 5000 rpm / min for 30 - 50 s to prepare an electron transport layer.

[0103] 8. An 80 - 100 nm thick silver film was evaporated on the electron transport layer in step 7 to obtain an inorganic perovskite solar cell.

[0104] Experimental results: The performance of the solar cell was tested. As shown, under the irradiation of standard light intensity of AM1.5, 100 mW / cm², the open-circuit voltage of the solar cell prepared in this example was 1.152 V, the short-circuit current density was 19.69 mA / cm², the fill factor was 81.12%, and the efficiency was 18.51%. Figure 8 Shown, under the irradiation of standard light intensity of AM1.5, 100 mW / cm², 2 the open-circuit voltage of the solar cell prepared in this example was 1.152 V, the short-circuit current density was 19.69 mA / cm² 2 , the fill factor was 81.12%, and the efficiency was 18.51%.

[0105] In summary, a preparation method of an inorganic perovskite solar cell based on S-(2-aminoethyl)isothiouronium bromide hydrobromide is provided. The S-(2-aminoethyl)isothiouronium bromide hydrobromide molecules are spin-coated on the surface of the perovskite film and annealed to obtain an upper interface passivation layer. During the annealing process, the sulfur element and amino group in one end of the molecule have an interaction force with lead in the inorganic perovskite, showing a negative end, and the other end amino group is exposed on the surface layer, showing a positive end, which accelerates the charge extraction. In addition, it also plays a role in in-situ passivation and improving the crystallization quality, and finally obtains a highly efficient and stable single-junction perovskite solar cell and a tandem solar cell. It should be further noted that the preparation method of the inorganic perovskite solar cell based on S-(2-aminoethyl)isothiouronium bromide hydrobromide according to the present invention is not only applicable to inorganic perovskites, but also applicable to organic-inorganic hybrid perovskites and crystalline silicon / perovskite tandem solar cells. The light-absorbing layer prepared by this method can be applied to the following structural devices:

[0106] a. Inorganic perovskite single-junction solar cell;

[0107] b. Hybrid perovskite single-junction solar cell;

[0108] c. Inorganic perovskite / tin-lead perovskite tandem solar cell;

[0109] d. Inorganic perovskite / crystalline silicon tandem solar cell;

[0110] e. Hybrid perovskite / crystalline silicon tandem solar cell.

[0111] Based on the above description, in the present invention, by applying S-(2-aminoethyl)isothiouronium bromide hydrobromide as a passivation material to the surface of the inorganic perovskite film, a uniform passivation layer is formed on the perovskite surface, significantly improving the electric field distribution between the perovskite layer and the electron transport layer, promoting the separation and transport of carriers, and suppressing non-radiative recombination. The amino group and thiourea group in the S-(2-aminoethyl)isothiouronium bromide hydrobromide molecule can form stable coordination bonds with the uncoordinated lead ions (Pb 2 +) on the perovskite surface, thereby effectively anchoring on the surface. At the same time, the bromide ions (Br-) in the S-(2-aminoethyl)isothiouronium bromide hydrobromide can fill the halogen vacancies in the perovskite lattice, further reducing the defect density. The interfacial characteristics between the perovskite and the electron transport layer are significantly improved, thereby enhancing the photoelectric conversion efficiency and stability of the battery.

[0112] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing an upper interface passivation layer of an inorganic perovskite solar cell, characterized in that, Spin-coat a molecular solution with a certain concentration on the perovskite surface; the molecule is S-(2-aminoethyl)isothiouronium bromide hydrobromide; the concentration of the molecular solution is 0.5 - 1.0 mg / mL.

2. The preparation method according to claim 1, characterized in that, The upper interface passivation layer is prepared by spin-coating a passivating agent solution followed by annealing. The spin-coating speed is 3000 - 5000 rpm / min and the time is 30 - 50 s; the annealing conditions are: annealing at 70 - 90 °C for 5 - 10 min in a nitrogen environment.

3. The preparation method according to claim 1, characterized in that, The solvent of the molecular solution is a mixed solution of isopropanol:ethanol = 1:

1.

4. A preparation method of an S-(2-aminoethyl)isothiouronium bromide hydrobromide field-passivated inorganic perovskite solar cell, characterized in that, It includes the following steps: (1) Prepare a hole transport layer on a transparent conductive substrate; (2) Spin-coat the inorganic perovskite CsPbI 3-x Br x precursor solution on the hole transport layer, and prepare a perovskite absorption layer with a thickness of 300 nm - 800 nm after annealing; (3) Spin-coat a passivating solution containing S-(2-aminoethyl)isothiouronium bromide hydrobromide molecules on the perovskite absorption layer, and prepare the upper interface passivation layer after annealing; (4) Prepare an electron transport layer on the upper interface passivation layer; (5) Prepare a metal electrode on the electron transport layer; The upper interface passivation layer is prepared by the method described in any one of claims 1 - 3.

5. The preparation method according to claim 4, characterized in that, The solvent of the perovskite precursor solution in step (2) is a mixed solution of dimethylformamide and dimethyl sulfoxide, and the solute is an inorganic perovskite; the concentration of the solute is 0.6 - 0.8 mol / L.

6. The preparation method according to claim 4, characterized in that, The perovskite absorption layer in step (2) is prepared by spin-coating a perovskite precursor solution followed by annealing. The spin-coating speed is 3000 - 5000 rpm / min and the time is 90 - 110 s; the annealing conditions are annealing at 180 - 200 °C for 10 - 15 min in ambient air.

7. The preparation method according to claim 3, characterized in that, The transparent conductive substrate is one of FTO and ITO conductive glasses; the hole transport layer is NiO x , one of SAM and PTAA; the electron transport layer is one of PCBM, C 60 , and SnO2; the metal electrode is one of the metal wires or metal grid lines of silver electrode, gold electrode, and copper electrode.

8. A field-passivated inorganic perovskite solar cell based on S-(2-aminoethyl)isothiouronium bromide hydrobromide, characterized in that, Prepared by the preparation method described in any one of claims 4 - 7, the structure of the inorganic perovskite solar cell is stacked from bottom to top in sequence as: a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an upper interface passivation layer, an electron transport layer, and a metal electrode; the upper interface passivation layer is a passivating solution with a concentration of 0.5 - 1.0 mg / mL of S-(2-aminoethyl)isothiouronium bromide hydrobromide molecules spin-coated on the perovskite absorption layer.

9. A preparation method of an S-(2-aminoethyl)isothiouronium bromide hydrobromide field-passivated inorganic perovskite solar cell, characterized in that, This upper interface passivation is applicable to the following structural devices: a. Inorganic perovskite single-junction solar cells; b. Hybrid perovskite single-junction solar cells; c. Inorganic perovskite / tin-lead perovskite tandem solar cells; d. Inorganic perovskite / crystalline silicon tandem solar cells; e. Hybrid perovskite / crystalline silicon tandem solar cells.

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