A perovskite solar cell and a preparation method thereof

Abstract

The present invention provides a perovskite solar cell and a preparation method thereof, belonging to the field of solar cells. The modifier layer A'A n B n X 3n+1 in which B is derived from the light-absorbing layer, eliminating the defects caused by B metal ion clusters in the light-absorbing layer. The generated A'A n B n X 3n+1 strengthens the interaction between the modifier layer and the light-absorbing layer through ionic bonds, further compensating for the defects caused by vacancies and grain boundaries in the light-absorbing layer, and improving the photoelectric conversion efficiency and stability of the battery. In addition, by preparing a two-dimensional perovskite modifier layer on the surface of the perovskite light-absorbing layer, on the one hand, a more favorable energy level arrangement can be formed to promote the transfer of carriers from the perovskite light-absorbing layer to the charge transport layer, thereby reducing the loss of reverse electron transfer and current leakage and improving the photoelectric conversion efficiency; on the other hand, it can also inhibit ion migration, which helps to reduce the hysteresis effect and improve the stability.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and particularly relates to a perovskite solar cell and a preparation method thereof. Background Art

[0002] A perovskite solar cell is a solar cell that uses a perovskite-type organometallic halide semiconductor as a light-absorbing material. The perovskite solar cell is the third-generation solar cell after the crystalline silicon solar cell and the thin-film solar cell, and has the advantages of simple structure, high photoelectric conversion efficiency, low cost, etc., and has attracted the attention of many countries around the world.

[0003] At present, the perovskite solar cell still has certain technical defects. Due to its rapid growth and high-temperature annealing process, a large number of defects will be formed at the interface between the perovskite light-absorbing layer and its corresponding transport layer, such as a large number of grain boundaries and vacancy defects. The formation of defects will result in low photoelectric conversion efficiency and poor stability of the battery device. In order to improve the efficiency and stability of the battery device, the prior art usually adds additives to the perovskite precursor solution, adopts a packaging technology or uses a new type of electron or hole transport layer material, but the photoelectric conversion efficiency and stability of the battery still need to be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a perovskite solar cell and a preparation method thereof, and the perovskite solar cell of the present invention has high photoelectric conversion efficiency and stability.

[0005] The present invention provides a perovskite solar cell, which includes a conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a two-dimensional perovskite modification layer, a hole transport layer and a metal electrode stacked in sequence;

[0006] The two-dimensional perovskite modification layer is prepared on the perovskite light-absorbing layer;

[0007] The chemical composition of the two-dimensional perovskite modification layer is A’A n B n X 3n+1 ; the A’ includes C 4 H 12 N + 、C 3 H 8 N + 、C 2 H 8 N + and CN 3 H 6 + One of them; the n is an integer from 1 to 10; the A includes CH 6 N + 、CH 5 N2 + , C 2 H 7 N 2 + and C 3 H 9 N + or one of C, H, and N; X is one of Cl - , Br - and I - or one or two of them; B is a divalent metal ion; B is derived from the perovskite light-absorbing layer.

[0008] Preferably, B includes Ge 2+ , Sn 2+ , Pb 2+ , Cu 2+ and Mn 2+ or one of them.

[0009] Preferably, the chemical composition of the perovskite light-absorbing layer is DBI 3 ; D includes CH 6 N + , CH 5 N 2 + and Cs + or one or more of them.

[0010] Preferably, the chemical composition of the electron transport layer is an inorganic oxide electron transport material or an organic electron transport material.

[0011] Preferably, the inorganic oxide electron transport material includes one of zinc oxide, tin dioxide, tungsten oxide, and titanium dioxide; the organic electron transport material includes one of [6,6]-phenyl C 71 butyrate methyl ester, [6,6]-phenyl C 61 butyrate methyl ester, and organic fullerene materials.

[0012] Preferably, the chemical composition of the hole transport layer includes one of 2,2’,7,7’-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], copper phthalocyanine, cuprous thiocyanate, poly(3-hexylthiophene), and nickel oxide.

[0013] Preferably, the thickness of the two-dimensional perovskite modification layer is 3 - 50 nm.

[0014] The present invention also provides a method for preparing the perovskite solar cell described in the above solution, including the following steps:

[0015] Coat a dispersion of the corresponding constituent materials of the electron transport layer onto a conductive substrate, and perform a first annealing to form the electron transport layer;

[0016] Coat a perovskite light-absorbing layer precursor solution onto the surface of the electron transport layer, and perform a second annealing to form the perovskite light-absorbing layer;

[0017] Coat an organic solution containing A’X and AX onto the surface of the perovskite light-absorbing layer, and perform a third annealing to form a two-dimensional perovskite modification layer; the molar ratio of A’X to AX is 1:1 to 10;

[0018] Coat a dispersion of the corresponding constituent materials of the hole transport layer onto the surface of the two-dimensional perovskite modification layer to form the hole transport layer;

[0019] Evaporate the raw materials of the metal electrode onto the hole transport layer to form the metal electrode, thereby obtaining the perovskite solar cell.

[0020] Preferably, the temperature of the third annealing is 60 to 120 °C, and the heat preservation time is 1 to 30 min.

[0021] Preferably, the total solute concentration of the organic solution containing A’X and AX is 0.1 to 20 mmol / L.

[0022] The present invention provides a perovskite solar cell, comprising a conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a two-dimensional perovskite modification layer, a hole transport layer, and a metal electrode that are stacked in sequence; the two-dimensional perovskite modification layer is prepared on the perovskite light-absorbing layer; the chemical composition of the two-dimensional perovskite modification layer is A’A n B n X 3n+1 ; the A’ includes C 4 H 12 N + 、C 3 H 8 N + 、C 2 H 8 N + and CN 3 H 6 + One of them; the n is an integer from 1 to 10; the A includes CH 6 N + 、CH 5 N 2 + 、C 2 H 7 N 2 + and C 3 H 9 N +One of the following; X is Cl - 、Br - and I - One or two of the following; B is a divalent metal ion; B is derived from the perovskite light-absorbing layer. In the present invention, the two-dimensional perovskite modification layer A’A n B n X 3n+1 The B in is derived from the perovskite light-absorbing layer, eliminating the defects caused by B metal ion clusters in the perovskite light-absorbing layer. The generated A’A n B n X 3n+1 Strengthens the interaction between the two-dimensional perovskite modification layer and the perovskite light-absorbing layer through ionic bonds, further compensating for the defects caused by vacancies and grain boundaries in the perovskite light-absorbing layer. Therefore, the two-dimensional perovskite modification layer prepared in the present invention improves the interfacial charge transfer between the perovskite light-absorbing layer and the electron transport layer / hole transport layer, effectively improving the photoelectric conversion efficiency and stability of the perovskite solar cell. In addition, by preparing a two-dimensional perovskite modification layer on the surface of the perovskite light-absorbing layer, the present invention can, on the one hand, form a more favorable energy level arrangement, promote the transfer of carriers from the perovskite light-absorbing layer to the charge transport layer, thereby reducing the loss of reverse electron transfer and current leakage and improving the photoelectric conversion efficiency; on the other hand, it can also inhibit ion migration, contributing to reducing the hysteresis effect and improving the stability. Description of the Drawings

[0023] Figure 1 Is the structural diagram of the perovskite solar cell of the present invention;

[0024] Figure 2 Is the SEM image of the perovskite layer solar cell of Example 1;

[0025] Figure 3 Is the J-V performance curve of the perovskite layer solar cell of Example 1 and the perovskite layer solar cell of Comparative Example 1;

[0026] Figure 4 Is the stability test result of the perovskite layer solar cell of Example 2 and the perovskite layer solar cell of Comparative Example 1. Detailed Embodiments

[0027] The present invention provides a perovskite solar cell, comprising a conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a two-dimensional perovskite modification layer, a hole transport layer, and a metal electrode stacked in sequence;

[0028] The two-dimensional perovskite modification layer is prepared on the perovskite light-absorbing layer;

[0029] The chemical composition of the two-dimensional perovskite modification layer is A’A n B n X3n+1 ; said A' includes C 4 H 12 N + , C 3 H 8 N + , C 2 H 8 N + and CN 3 H 6 + ; said n is an integer from 1 to 10; said A includes CH 6 N + , CH 5 N 2 + , C 2 H 7 N 2 + and C 3 H 9 N + ; said X is one of Cl - , Br - and I - ; said B is a divalent metal ion; said B is derived from the perovskite light-absorbing layer.

[0030] The perovskite solar cell provided by the present invention includes a conductive substrate. In the present invention, the thickness of the conductive substrate is preferably 0.5 - 2.5 cm, more preferably 1 - 2 cm, and further preferably 1.5 - 1.8 cm. In the present invention, the conductive substrate preferably includes fluorine-doped tin dioxide conductive glass or indium tin oxide transparent conductive film glass.

[0031] The perovskite solar cell provided by the present invention includes an electron transport layer attached to the surface of the conductive substrate. In the present invention, the thickness of the electron transport layer is preferably 20 - 200 nm, more preferably 50 - 150 nm, and further preferably 70 - 100 nm. In the present invention, the chemical composition of the electron transport layer is preferably an inorganic oxide electron transport material or an organic electron transport material; the inorganic oxide electron transport material preferably includes one of zinc oxide, tin dioxide, tungsten oxide, and titanium dioxide; the organic electron transport material preferably includes [6,6]-phenyl C 71 butyrate methyl ester, [6,6]-phenyl C 61 butyrate methyl ester, and one of organic fullerene materials.

[0032] The perovskite solar cell provided by the present invention includes a perovskite light-absorbing layer attached to the surface of the electron transport layer. In the present invention, the thickness of the perovskite light-absorbing layer is preferably 300-800 nm, more preferably 400-600 nm, and further preferably 450-500 nm. In the present invention, the chemical composition of the perovskite light-absorbing layer is preferably DBI 3 ; the D preferably includes CH 6 N + 、CH 5 N 2 + and Cs + or one or more of them; the B is a divalent metal ion; the divalent metal ion preferably includes Ge 2+ 、Sn 2 + 、Pb 2+ 、Cu 2+ and Mn 2+ or one of them. In the embodiment of the present invention, the chemical composition of the perovskite light-absorbing layer is specifically CH 5 N 2 PbI 3 .

[0033] The perovskite solar cell provided by the present invention includes a two-dimensional perovskite modification layer attached to the surface of the perovskite light-absorbing layer. In the present invention, the thickness of the two-dimensional perovskite modification layer is preferably 3-50 nm, more preferably 10-40 nm, and further preferably 20-30 nm. In the present invention, the two-dimensional perovskite modification layer is prepared in-situ on the perovskite light-absorbing layer; the chemical composition of the two-dimensional perovskite modification layer is A’A n B n X 3n+1 ; the A’ includes C 4 H 12 N + 、C 3 H 8 N + 、C 2 H 8 N + and CN 3 H 6 + or one of them; the n is an integer from 1 to 10, preferably an integer from 2 to 8, and more preferably an integer from 4 to 6. The B is derived from the perovskite light-absorbing layer. In the embodiment of the present invention, the chemical composition of the two-dimensional perovskite modification layer is specifically CN 3 H 6 (CH 6 N) 2 Pb 2 I 7 .

[0034] In the two-dimensional perovskite modification layer A’A n B n X 3n+1 of the present invention, B is derived from the perovskite light-absorbing layer, eliminating the defects caused by B metal ion clusters in the perovskite light-absorbing layer. The generated A’A n B n X 3n+1 strengthens the interaction between the two-dimensional perovskite modification layer and the perovskite light-absorbing layer through ionic bonds, further compensating for the defects caused by vacancies and grain boundaries in the perovskite light-absorbing layer. Therefore, the two-dimensional perovskite modification layer prepared by the present invention improves the interfacial charge transfer between the perovskite light-absorbing layer and the electron transport layer / hole transport layer, effectively improving the photoelectric conversion efficiency and stability of the perovskite solar cell. In addition, by preparing a two-dimensional perovskite modification layer on the surface of the perovskite light-absorbing layer, on the one hand, a more favorable energy level arrangement can be formed, promoting the transfer of carriers from the perovskite light-absorbing layer to the charge transport layer, thereby reducing the loss of reverse electron transfer and current leakage and improving the photoelectric conversion efficiency; on the other hand, it can also inhibit ion migration, contributing to reducing photocurrent hysteresis and improving stability.

[0035] The perovskite solar cell provided by the present invention includes a hole transport layer attached to the surface of the two-dimensional perovskite modification layer. In the present invention, the thickness of the hole transport layer is preferably 5-200 nm, more preferably 50-150 nm, and further preferably 60-120 nm. In the present invention, the chemical composition of the hole transport layer preferably includes one of 2,2’,7,7’-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], copper phthalocyanine, cuprous thiocyanate, poly(3-hexylthiophene), and nickel oxide. The chemical composition of the hole transport layer preferably further includes 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide. The 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide can improve the hole transport rate of the hole transport layer. In the examples of the present invention, the chemical composition of the hole transport layer is 2,2’,7,7’-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene, 4-tert-butylpyridine, and lithium bis(trifluoromethanesulfonyl)imide.

[0036] The perovskite solar cell provided by the present invention includes a metal electrode attached to the surface of the hole transport layer. In the present invention, the thickness of the metal electrode is preferably 50-200 nm, more preferably 80-180 nm, and further preferably 100-150 nm. The metal electrode preferably includes one of Al, Ag, Cu, and Au. In the examples of the present invention, the metal electrode is Au.

[0037] The structure of the perovskite solar cell of the present invention can be seen in detail in Figure 1 , including a conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a two-dimensional perovskite modification layer, a hole transport layer, and a metal electrode stacked in sequence.

[0038] The present invention provides a method for preparing the perovskite solar cell described in the above solution, including the following steps:

[0039] Coat the dispersion of the corresponding constituent substances of the electron transport layer onto the conductive substrate, and perform the first annealing to form the electron transport layer;

[0040] Coat the perovskite light-absorbing layer precursor solution onto the surface of the electron transport layer, and perform the second annealing to form the perovskite light-absorbing layer;

[0041] Coat the organic solution containing A’X and AX onto the surface of the perovskite light-absorbing layer, and perform the third annealing to form the two-dimensional perovskite modification layer; the molar ratio of A’X to AX is 1:1 to 10;

[0042] Coat the dispersion of the corresponding constituent substances of the hole transport layer onto the surface of the two-dimensional perovskite modification layer to form the hole transport layer;

[0043] Evaporate the raw material of the metal electrode onto the hole transport layer to form the metal electrode, and obtain the perovskite solar cell.

[0044] In the present invention, the dispersion of the corresponding constituent substances of the electron transport layer is coated onto the conductive substrate, and the first annealing is performed to form the electron transport layer. In the present invention, the preparation method of the dispersion of the corresponding constituent substances of the electron transport layer preferably includes: dispersing the corresponding constituent substances of the electron transport layer in a first dispersant. The first dispersant preferably includes one of deionized water, ethanol, methanol, and butanol. The content of the corresponding constituent substances of the electron transport layer in the dispersion of the corresponding constituent substances of the electron transport layer is preferably 1 to 5 wt%, more preferably 2 to 4 wt%. The present invention has no special limitation on the dispersion, and it can be dispersed evenly by using a method well-known to those skilled in the art. In the present invention, the coating method is preferably spin coating, the rotation speed of the spin coating is preferably 2000 to 5000 rpm / min, more preferably 3000 to 4500 rpm / min, further preferably 3500 to 4000 rpm / min, and the time is preferably 30 s. The spin coating is preferably performed in air. In the present invention, the temperature of the first annealing is preferably 100 to 200 °C, more preferably 120 to 180 °C, further preferably 150 to 160 °C, and the time is preferably 10 to 90 min, more preferably 30 to 80 min, further preferably 50 to 60 min. The first annealing is preferably performed in air. After the first annealing, the residual first dispersant in the spin coating process is removed, and a dense electron transport layer is formed.

[0045] After forming the electron transport layer, the perovskite light-absorbing layer precursor solution of the present invention is coated on the surface of the electron transport layer, and a second annealing is performed to form a perovskite light-absorbing layer. In the present invention, the perovskite light-absorbing layer precursor solution preferably comprises an organic solution containing BI 2 and an organic solution containing DI and CH 6 NCl. In the present invention, the preparation method of the organic solution containing BI 2 preferably comprises mixing BI 2 with a first organic solvent for a first mixing to obtain the organic solution containing BI 2 . The first mixing is preferably carried out in a glove box. The present invention has no special limitation on the first mixing, and it can be mixed evenly by using a scheme well-known to those skilled in the art. The concentration of BI 2 in the organic solution containing BI 2 is preferably 0.5 to 2 mol / L, more preferably 1.3 to 1.8 mol / L, and further preferably 1.4 to 1.6 mol / L. The first organic solvent preferably comprises a mixed solution of DMF and DMSO, and the volume ratio of DMF to DMSO is preferably 9:0.1 to 2, more preferably 9:0.5 to 1.5, and further preferably 9:0.8 to 1.2. In the present invention, the preparation method of the organic solution containing DI and CH 6 NCl preferably comprises mixing DI and CH 6 NCl with a second organic solvent for a second mixing to obtain the organic solution containing DI and CH 6 NCl. In the present invention, the total concentration of DI and CH 6 NCl in the organic solution containing DI and CH 6 NCl is preferably 0.1 to 1 mol / L, more preferably 0.5 to 0.7 mol / L. In the present invention, the molar ratio of DI to CH 6 NCl is preferably 4:1. CH 6 NCl can promote the formation of the perovskite light-absorbing layer and improve the film quality of the perovskite light-absorbing layer. In the present invention, the second organic solvent is preferably one of isopropanol, ethanol, methanol, dichloromethane, chloroform, butanol, tetrahydrofuran, and acetone. In the present invention, the coating method is preferably spin coating, and the rotation speed of the spin coating is preferably 1000 to 3000 rpm / min, more preferably 1200 to 2500 rpm / min, and further preferably 1500 to 2000 rpm / min, and the time is preferably 10 to 60 s, more preferably 20 to 50 s, and further preferably 30 to 40 s. The spin coating is preferably carried out in a glove box.

[0046] The perovskite light-absorbing layer precursor solution of the present invention is coated on the surface of the electron transport layer. The second annealing preferably includes: coating an organic solution containing BI 2 on the surface of the electron transport layer, and performing the second' annealing to form a BI 2 layer; coating an organic solution of DI and CH 6 NCl on the BI 2 layer, and then performing the second'' annealing to obtain the perovskite light-absorbing layer. In the present invention, the temperature of the second' annealing is preferably 60-90°C, more preferably 70-80°C, and the time is preferably 0.5-3 min, more preferably 1-2 min. The temperature of the second'' annealing is preferably 140-160°C, more preferably 145-150°C, and the time is preferably 5-15 min, more preferably 8-12 min. The second' annealing is preferably carried out in a glove box. The second'' annealing is preferably carried out in air, and trace amounts of water in the air promote the crystallization of the perovskite light-absorbing layer. During the second' annealing process, the residual first organic solvent in the spin-coating process is removed, so that BI 2 adheres to the surface of the electron transport layer. During the subsequent second'' annealing process, BI 2 reacts with DI to form DBI 3 , that is, the perovskite light-absorbing layer.

[0047] After forming the perovskite light-absorbing layer, the present invention coats an organic solution containing A’X and AX on the surface of the perovskite light-absorbing layer, and performs a third annealing to form a two-dimensional perovskite modification layer. In the present invention, the preparation method of the organic solution containing A’X and AX preferably includes performing a third mixing of A’X and AX with a third organic solvent to obtain the organic solution containing A’X and AX. The third mixing is preferably performed in a glove box. The present invention has no special limitation on the third mixing, and it can be mixed evenly by using a method well-known to those skilled in the art. In the present invention, the molar ratio of A’X to AX is 1:1 to 10, preferably 1:4 to 8, and more preferably 1:5 to 6. In the present invention, the third organic solvent is preferably one or more of methanol, isopropanol, acetone, tetrahydrofuran, dichloromethane, chloroform, ethanol, and butanol. The total concentration of A’X and AX in the organic solution containing A’X and AX is preferably 0.1 to 20 mmol / L, more preferably 5 to 15 mmol / L, and further preferably 10 to 12 mmol / L. In the present invention, the coating method is preferably spin coating, the rotation speed of the spin coating is preferably 4000 rpm / min, and the time is preferably 30 s. The spin coating is preferably performed in a glove box. The temperature of the third annealing is preferably 60 to 120 °C, more preferably 70 to 100 °C, and further preferably 80 to 90 °C, and the time is preferably 1 to 30 min, more preferably 5 to 25 min, and further preferably 10 to 15 min. The third annealing is preferably performed in a glove box filled with argon. A’X and AX react with the B metal ion clusters on the surface of the perovskite light-absorbing layer at the third annealing temperature to generate A’A n B n X 3n+1 , and remove the residual solvent in the two-dimensional perovskite modification layer.

[0048] After forming the two-dimensional perovskite modification layer, the present invention coats a dispersion of the corresponding constituent materials of the hole transport layer onto the surface of the two-dimensional perovskite modification layer to form a hole transport layer. The preparation method of the dispersion of the corresponding constituent materials of the hole transport layer in the present invention preferably disperses the corresponding constituent materials of the hole transport layer in a second dispersant. The second dispersant preferably includes one or more of toluene, chlorobenzene, and xylene. When the corresponding constituent materials of the hole transport layer are 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4-tert-butylpyridine, and lithium bis(trifluoromethanesulfonyl)imide, the content of 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene in the dispersion of the corresponding constituent materials of the hole transport layer is preferably 60-100 mg / mL, more preferably 72.3-80 mg / mL, the content of 4-tert-butylpyridine is preferably 20-30 mg / mL, more preferably 25-28.8 μL / mL, and the content of lithium bis(trifluoromethanesulfonyl)imide is preferably 20-40 mg / mL, more preferably 30.8-35 mg / mL. The present invention has no special limitation on the dispersion, and it can be dispersed evenly by using a method well-known to those skilled in the art. In the present invention, the coating method is preferably spin coating, the rotation speed of the spin coating is preferably 4000 rpm / min, and the time is preferably 30 s. The spin coating is preferably carried out in a glove box. In the present invention, the solvent in the dispersion includes one of toluene, chlorobenzene, and xylene.

[0049] After forming the hole transport layer, the present invention evaporates the raw materials of the metal electrode onto the hole transport layer to form a metal electrode, and obtains the perovskite solar cell. In the present invention, the vacuum degree of the evaporation is preferably less than 1×10 -3 Pa, and the speed is preferably more preferably even more preferably

[0050] To further illustrate the present invention, the perovskite solar cell and its preparation method provided by the present invention will be described in detail below with reference to the drawings and examples, but they cannot be understood as limiting the protection scope of the present invention.

[0051] Example 1

[0052] Disperse SnO 2 in deionized water to obtain a dispersion with a SnO 2 content of 2.5 Wt%. Spin coat the obtained dispersion on the conductive substrate FTO in air and then perform the first annealing at a temperature of 150°C for 30 min to form an electron transport layer with a thickness of 150 nm; the rotation speed of the spin coating is 4000 rpm / min, and the time is 30 s;

[0053] In a glove box, PbI 2 is dissolved in an organic solvent (the organic solvent is a mixed solvent of DMF and DMSO, and the volume ratio of DMF to DMSO is 9:1) to obtain a mixed solution with a concentration of 1.5 mol / L; the obtained mixed solution is spin-coated (the spin-coating speed is 1700 rpm / min and the time is 30 s) on the electron transport layer, and a second annealing is carried out for 1 min in a glove box filled with argon at 70 °C to form a PbI layer with a thickness of 400 nm 2 A solution of CH 5 N 2 I and CH 6 NCl in isopropanol is prepared to obtain an organic solution with a total concentration of 0.6 mol / L; the organic solution is spin-coated (the spin-coating speed is 2000 rpm / min and the time is 30 s) in the glove box on the PbI 2 layer, and then a second annealing is carried out in air at 150 °C for 15 min to form a CH 5 N 2 PbI 3 perovskite light-absorbing layer with a thickness of 400 nm;

[0054] In the glove box, a solution of CN 3 H 6 I and CH 6 NI in isopropanol is prepared to obtain an organic solution with a total concentration of 5 mmol / L containing CN 3 H 6 I and CH 6 NI; the organic solution is spin-coated (the spin-coating speed is 4000 rpm / min and the time is 30 s) in the glove box on the CH 5 N 2 PbI 3 perovskite light-absorbing layer, and a third annealing is carried out at 100 °C in a glove box filled with argon for 5 min to form a two-dimensional perovskite modification layer with a chemical composition of CN 3 H 6 (CH 6 N) 2 Pb 2 I 7 and a thickness of 5 nm;

[0055] Disperse 2,2’,7,7’-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene with chlorobenzene, dope 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide to obtain a dispersion of the corresponding composition of the hole transport layer. The content of 2,2’,7,7’-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene in the dispersion is 72.3 mg / mL, the content of 4-tert-butylpyridine is 28.8 μL / mL, and the content of lithium bis(trifluoromethanesulfonyl)imide is 30.8 mg / mL. Spin-coat (at a rotation speed of 4000 rpm / min for 30 s) the obtained dispersion on the two-dimensional perovskite modification layer in a glove box to form a hole transport layer with a thickness of 150 nm;

[0056] Under the condition of a vacuum degree of 6.5×10 -4 Pa, evaporate the metal electrode Au at a speed of on the hole transport layer to form a metal electrode with a thickness of 100 nm, and obtain the perovskite solar cell.

[0057] Perform SEM analysis on the perovskite light-absorbing layer and modification layer prepared in Example 1, and the results are as Figure 2 shown. It can be seen from Figure 2 that in the surface morphology of the perovskite light-absorbing layer of this example, the grain size is relatively large, reaching about 1 μm, there are no obvious voids, the grain boundaries are passivated by the two-dimensional perovskite modification layer, and there is an obvious distribution of two-dimensional perovskite modification layer flakes. It shows that the passivated perovskite light-absorbing layer has few defects and low film roughness.

[0058] Example 2

[0059] The only difference from Example 1 is that the total concentration of the organic solution containing CNH 3 H 6 I and CH 6 NI used in preparing the two-dimensional perovskite modification layer is 10 mmol / L.

[0060] Example 3

[0061] The only difference from Example 1 is that the total concentration of the organic solution containing CNH 3 H 6 I and CH 6 NI used in preparing the two-dimensional perovskite modification layer is 15 mmol / L.

[0062] Example 4

[0063] The only difference from Example 1 is that the total concentration of the organic solution containing CNH 3 H 6 I and CH 6 NI used in preparing the two-dimensional perovskite modification layer is 20 mmol / L.

[0064] Comparative Example 1

[0065] The only difference from Example 1 is that the two-dimensional perovskite modification layer was not prepared.

[0066] Under AM1.5G, 100mW / cm 2 Under the test conditions, a solar simulator was used to obtain the J-V performance curves of the perovskite solar cells of Example 1 and Comparative Example 1, as Figure 3 shown and shown in Table 1.

[0067] Table 1 J-V parameters of perovskite solar cell devices under blank conditions and after passivation

[0068] Voc (V) <![CDATA[Jsc (mA·cm -2 )]]> FF PCE (%) Comparative Example 1 1.14 24.65 0.78 21.9 Example 1 1.16 24.70 0.81 23.2

[0069] From Figure 3 and Table 1, it can be seen that the short-circuit current of the perovskite solar cell in the comparative example is 24.65 mA / cm 2 , the open-circuit voltage is 1.14 V, the fill factor is 0.78, and the energy conversion efficiency is 21.9%. While the short-circuit current of the perovskite solar cell in Example 1 increased to 24.7 mA / cm 2 , the open-circuit voltage increased to 1.16 V, the fill factor increased to 0.81, and the energy conversion efficiency increased to 23.2%.

[0070] The perovskite solar cells of Example 2 and Comparative Example 1 were subjected to a stability test: placed in a dry and dark environment, the photoelectric conversion efficiency was measured every 24 hours for the first 200 hours, and every 168 hours after 200 hours. The stability test results are as Figure 4 shown. From Figure 4 it can be seen that the perovskite solar cell of Example 1 still maintained 82% of the photoelectric conversion efficiency after 1440 hours, while the photoelectric conversion efficiency of the perovskite solar cell of Comparative Example 1 decayed to 59% of the initial value. The stability test results show that the passivated perovskite solar cell has increased stability due to the reduction of defects in the perovskite light-absorbing layer.

[0071] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. Other embodiments can be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A perovskite solar cell, characterized in that, it comprises a conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a two-dimensional perovskite modification layer, a hole transport layer and a metal electrode which are stacked in sequence; the two-dimensional perovskite modification layer is prepared on the perovskite light-absorbing layer; The chemical composition of the two-dimensional perovskite modification layer is A'A n B n X 3n+1 ; A' is CN 3 H 6 + ; n is 2; A is CH 6 N + ; X is Cl − , Br − and I − or one or two of them; B is a divalent metal ion; B is derived from the perovskite light-absorbing layer.

2. The perovskite solar cell according to claim 1, characterized in that, The said B includes Ge 2+ , Sn 2+ , Pb 2+ , Cu 2 + and Mn 2+ and one of them 3. The perovskite solar cell according to claim 1 or 2, characterized in that, The chemical composition of the perovskite light-absorbing layer is DBI 3 ; The D includes CH 6 N + 、CH 5 N 2 + and Cs + one or more of them.

4. The perovskite solar cell according to claim 1, characterized in that, the chemical composition of the electron transport layer is an inorganic oxide electron transport material or an organic electron transport material.

5. The perovskite solar cell according to claim 4, characterized in that, The inorganic oxide electron transport material includes one of zinc oxide, tin dioxide, tungsten oxide, and titanium dioxide; the organic electron transport material includes [6,6]-phenyl C 71 methyl butyrate, [6,6]-phenyl C 61 methyl butyrate, and one of organic fullerene materials.

6. The perovskite solar cell according to claim 1, characterized in that, the chemical composition of the hole transport layer includes one of 2,2’,7,7’-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene, poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], copper phthalocyanine, cuprous thiocyanate, poly(3-hexylthiophene) and nickel oxide.

7. The perovskite solar cell according to claim 1, characterized in that, the thickness of the two-dimensional perovskite modification layer is 3 - 50 nm.

8. The preparation method of the perovskite solar cell according to any one of claims 1 - 7, characterized in that, it comprises the following steps: Coating the dispersion liquid of the corresponding composition substances of the electron transport layer onto the conductive substrate, and performing the first annealing to form the electron transport layer; Coating the perovskite light-absorbing layer precursor solution onto the surface of the electron transport layer, and performing the second annealing to form the perovskite light-absorbing layer; Coating the organic solution containing A’X and AX onto the surface of the perovskite light-absorbing layer, and performing the third annealing to form the two-dimensional perovskite modification layer; the molar ratio of A’X to AX is 1:1 - 10; Coating the dispersion liquid of the corresponding composition substances of the hole transport layer onto the surface of the two-dimensional perovskite modification layer to form the hole transport layer; Evaporating the raw material of the metal electrode onto the hole transport layer to form the metal electrode, thus obtaining the perovskite solar cell.

9. The preparation method according to claim 8, characterized in that, the temperature of the third annealing is 60 - 120 °C, and the heat preservation time is 1 - 30 min.

10. The preparation method according to claim 8, characterized in that, the total solute concentration of the organic solution containing A’X and AX is 0.1 - 20 mmol / L.

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