A Method for Simultaneously Improving the Open-Circuit Voltage and Stability of All-Rough-Surface Perovskite / Silicon Heterojunction Solar Cells

Abstract

A method for simultaneously improving the open-circuit voltage and stability of a full-textured perovskite / silicon heterojunction solar cell belongs to the technical field of solar cells. The solar cell is composed of a silicon bottom cell, a microcrystalline silicon tunneling composite layer, and a perovskite top cell. The two-dimensional / three-dimensional perovskite bulk heterojunction photoabsorbing layer of the perovskite top cell is prepared based on a vacuum-assisted two-step method. In the first step, lead iodide and cesium bromide are simultaneously vapor-deposited through a thermal evaporation vacuum deposition device to form an inorganic compound thin film mixed with lead iodide and cesium bromide. In the second step, a ternary cation mixed organic ammonium salt solution of formamidinium, guanidinium, and thiophene-based organic ammonium is liquid-phase coated on the inorganic compound thin film. The introduction of guanidinium cations can inhibit the migration of halogen ions in the formamidinium-based three-dimensional perovskite thin film, and the two-dimensional perovskite based on thiophene-based organic ammonium is in-situ formed at the grain boundaries, thereby realizing the preparation of a high-performance full-textured perovskite / silicon heterojunction solar cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and particularly relates to a method for simultaneously improving the open-circuit voltage and stability of a full-textured perovskite / silicon tandem solar cell. Background Art

[0002] Regardless of the preparation process adopted, the efficiency of a single-junction solar cell has almost reached the theoretical limit, while the tandem complementary structure of solar cells with different bandgaps is expected to break through the single-junction Shockley-Queisser limit. In a tandem structure, high-energy photons generate high voltage in the top cell, and low-energy photons are absorbed in the bottom cell. The use of a material with a higher bandgap will reduce thermalization losses, and the collection of the remaining non-absorbed light by a material with a lower bandgap will reduce sub-bandgap losses.

[0003] Organic-inorganic hybrid three-dimensional perovskite has excellent optoelectronic properties and is considered to be the next-generation low-cost light-absorbing material. The general formula of three-dimensional perovskite is ABX3, where the A site is a monovalent cation located in the interstitial space of the [BX6] 4- octahedron. The A-site cations used in photovoltaic materials mainly include cesium ions, methylamine (MA) ions, and formamidine (FA) ions. If the ionic radius of the A-site cation is too large, the three-dimensional perovskite structure will turn into a two-dimensional layered structure. Since the bandgap of three-dimensional perovskite is usually greater than 1.5 eV, it can be paired with a crystalline silicon cell to prepare a perovskite / silicon tandem solar cell.

[0004] The preparation of the perovskite photoabsorbing layer in the all-textured perovskite / silicon heterojunction solar cell adopts a vacuum-assisted two-step method. The preparation method is simple and regardless of whether the substrate is a polished surface or a textured surface, it can fully cooperate with the industrialized production process of silicon bottom cells. However, in the current high-efficiency all-textured perovskite / silicon heterojunction solar cells, there is still much room for improvement in the open-circuit voltage and stability. For example, most of the previous work was based on the vacuum-assisted two-step method to prepare methylammonium lead iodide perovskite (MAPbI3, MA at the A site), and the open-circuit voltage was generally around 1.7 V, far lower than its theoretical value, indicating serious recombination in the heterojunction solar cell. Compared with the easily volatile methylammonium cation, the perovskite film based on formamidinium cation has high power conversion efficiency and higher stability, but it is prone to phase transformation, and the iodide ions in the perovskite film are prone to migration and form vacancies. It has been reported (Zhou Y. et al. Adv. Funct. Mater. 2019, 29, 1905739) that the introduction of guanidine (GA) ions can effectively inhibit the formation of halogen ion defects, but the ionic radius of guanidine is too large, which is likely to cause excessive tensile stress in the formamidinium perovskite, bringing adverse effects instead. The introduction of two-dimensional perovskite can release stress, but its insulating organic spacer cations limit the charge transport in the two-dimensional perovskite film. Therefore, the relationship between the two needs to be balanced. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for simultaneously improving the open-circuit voltage and stability of all-textured perovskite / silicon heterojunction solar cells.

[0006] The all-textured perovskite / silicon heterojunction solar cell described in the present invention is composed of a silicon bottom cell, a microcrystalline silicon tunneling composite layer, and a perovskite top cell. The microcrystalline silicon tunneling composite layer selects p-type microcrystalline silicon with a crystallization rate of 50%, and is prepared on the silicon bottom cell by plasma-enhanced chemical vapor deposition.

[0007] For the all-textured perovskite / silicon heterojunction solar cell described in the present invention, in terms of the preparation sequence: they are the back silver electrode, the back indium tin oxide transparent electrode, p-type amorphous silicon, intrinsic amorphous silicon, a micron-scale textured intrinsic monocrystalline silicon wafer, intrinsic amorphous silicon, n-type amorphous silicon, a p-type microcrystalline silicon tunneling composite layer with a crystallization rate of 50%, the hole transport layer spiro-TTB, the two-dimensional / three-dimensional hybrid heterojunction perovskite photoabsorbing layer, the passivation layer LiF, and the electron transport layer C 60, a protective layer of SnO2, a front indium tin oxide transparent electrode, an antireflection layer of MgF2, and a front silver grid line electrode. Among them, the back silver electrode, the back indium tin oxide transparent electrode, the back p-type amorphous silicon, the back intrinsic amorphous silicon, the intrinsic monocrystalline silicon wafer with a micron-level textured surface, the front intrinsic amorphous silicon, and the front n-type amorphous silicon form a crystalline silicon bottom cell; a hole transport layer of spiro-TTB, a two-dimensional / three-dimensional hybrid heterojunction perovskite light absorption layer, a passivation layer of LiF, and an electron transport layer of C 60 , a protective layer of SnO2, a front indium tin oxide transparent electrode, a front silver grid line electrode, and an antireflection layer of MgF2 form a perovskite top cell.

[0008] The crystalline silicon bottom cell is a full-textured (both the upper and lower surfaces of the crystalline silicon cell are in the morphology of commercial micron-level large textured surfaces, and the thin films prepared for each layer of the device need to maintain this textured surface morphology) amorphous silicon / crystalline silicon heterojunction structure. The two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer of the perovskite top cell is prepared based on a vacuum-assisted two-step method. In the first step, lead iodide and cesium bromide are simultaneously vapor-deposited through a thermal evaporation vacuum deposition device to form an inorganic compound thin film mixed with lead iodide and cesium bromide. In the second step, a ternary cation mixed organic ammonium salt solution of formamidine, guanidine, and thiophene-based organic ammonium is liquid-coated on this inorganic compound thin film, and a two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer is obtained in-situ through thermal annealing. The introduction of guanidine cations can inhibit the migration of halogen ions in the formamidinium-based three-dimensional perovskite thin film and inhibit the formation of its defects; at the same time, the in-situ formation of the thiophene-based organic ammonium two-dimensional perovskite at the grain boundaries not only passivates the defects at the grain boundaries of the mixed cation three-dimensional perovskite based on formamidine and guanidine but also releases the lattice stress brought by the introduction of guanidine ions in the three-dimensional perovskite, thereby improving its structural stability, greatly enhancing the open-circuit voltage and stability of the tandem solar cell, and thus realizing the preparation of a high-performance full-textured perovskite / crystalline silicon tandem solar cell.

[0009] In the preparation process of the perovskite light absorption layer in the full-textured perovskite / crystalline silicon tandem solar cell, in the first step, a thermal evaporation vacuum deposition device is used for vapor deposition, thereby replacing the traditional liquid phase method. By adjusting the vapor deposition rate ratio of lead iodide and cesium bromide and controlling it at 1:0.08, an inorganic compound thin film with a total thickness of 300 - 500 nm is obtained.

[0010] In the preparation process of the perovskite light absorption layer in the full-textured perovskite / crystalline silicon tandem solar cell, in the second step, the liquid coating method is adopted. A ternary cation mixed organic ammonium salt solution of formamidine, guanidine, and thiophene-based organic ammonium mixed in a certain proportion is liquid-coated on the inorganic compound thin film, and after thermal annealing on a hot stage at 140 - 160 °C for 20 - 40 minutes in an environment with a relative humidity of 30 - 60%, a two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer is obtained.

[0011] Further, the ternary cation mixed organic ammonium salt solution of formamidine, guanidine and thiophene organic ammonium is prepared by dissolving formamidine hydroiodide, guanidine hydroiodide and thiophene organic ammonium hydrohalide in an ethanol solution at a molar ratio of 1:0.05:0.02, and preferably, the thiophene organic ammonium hydrohalide is 2-thiopheneethylamine hydrobromide or 2-thiopheneethylamine hydrochloride. The two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer prepared by the method of the present invention, the bulk heterojunction is a structure formed by mixing two-dimensional perovskite and three-dimensional perovskite in a thin film, the perovskite guanidine ions are successfully introduced into the three-dimensional perovskite lattice, the formation and migration of iodide ion defects are suppressed, and at the same time, the formation of the two-dimensional / three-dimensional mixed heterojunction realizes the passivation of defects at the three-dimensional perovskite grain boundary, and the release of internal stress of the three-dimensional perovskite lattice.

[0012] Furthermore, the hole transport layer spiro-TTB, the passivation layer LiF, and the electron transport layer C 60 , anti-reflection layer MgF2, front silver grid line electrode and back silver electrode are deposited by thermal evaporation vacuum deposition equipment, the protective layer SnO2 is deposited by atomic layer deposition equipment, the back and front indium tin oxide transparent electrodes are deposited by physical vapor deposition equipment, the back and front intrinsic amorphous silicon, back p-type amorphous silicon, front n-type amorphous silicon, and microcrystalline silicon tunneling composite layer are deposited by plasma enhanced chemical vapor deposition.

[0013] Mechanism of the present invention:

[0014] In the process of growing the perovskite light absorption layer by vacuum-assisted two-step method in the full-texture perovskite / crystalline silicon tandem solar cell, on the one hand, the guanidine ions added in trace amounts in the second step of the mixed organic ammonium salt solution occupy the A position and produce strong interactions with the halogen ions and greatly increase the formation energy of the halogen vacancies, thereby significantly reducing the formation probability of iodine ion defects. However, the radius of the guanidine ions is too large, which easily causes tensile stress inside the lattice and destroys the stability of its structure. On the other hand, the thiophene organic ammonium added in trace amounts in the second step of the mixed organic ammonium salt solution reacts with the lead iodide in the inorganic compound film to form a two-dimensional / three-dimensional perovskite body phase heterojunction in situ, directly acting on the grain boundaries of the three-dimensional perovskite, greatly reducing the loss of carriers caused by non-radiative recombination due to grain boundary defects, and releasing the lattice stress caused by the introduction of guanidine ions in the three-dimensional perovskite. Finally, the tandem solar cell prepared by the ternary mixed cation scheme has been significantly improved in terms of open circuit voltage and stability.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) The method for preparing the in-situ two-dimensional / three-dimensional perovskite bulk heterojunction proposed by the present invention is simple and has a low operation process difficulty. Guanidinium ions are used to inhibit the formation of halogen ion defects, and the two-dimensional / three-dimensional bulk heterojunction formed by thiophene-based organic ammonium is used to passivate the defects at the grain boundaries and release the defects inside the three-dimensional perovskite lattice.

[0017] 2) The present invention provides an effective solution for preparing high-efficiency perovskite / silicon heterojunction solar cells. The vacuum-assisted two-step method is not easy to optimize the performance of the perovskite thin film. By specific combinations of the second-step organic ammonium cations, a gain effect is produced on the performance of the perovskite light absorption layer, laying a foundation for its application in all-textured perovskite / silicon heterojunction solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the all-textured perovskite / silicon heterojunction solar cell described in the present invention; the names of each part are: back silver electrode 10, back indium tin oxide transparent electrode 20, back p-type amorphous silicon 30, back intrinsic amorphous silicon 40, intrinsic monocrystalline silicon wafer 50 with a micron-scale texture, front intrinsic amorphous silicon 60, front n-type amorphous silicon 70, p-type microcrystalline silicon tunneling composite layer 80 with a crystallization rate of 50%, hole transport layer spiro-TTB 90, two-dimensional / three-dimensional hybrid heterojunction perovskite light absorption layer 100, passivation layer LiF 110, electron transport layer C 60 120, protective layer SnO2 130, front indium tin oxide transparent electrode 140, front silver grid line electrode 150, antireflection layer MgF2 160.

[0019] Figure 2 is a scanning electron microscope image of the surface of the perovskite light absorption layer prepared in Example 1 and Comparative Example 1 of the present invention;

[0020] Figure 3 is the I-V characteristic curve of the all-textured perovskite / silicon heterojunction solar cells prepared in Example 1 and Comparative Example 1 of the present invention under AM1.5G illumination.

[0021] Figure 4 is the performance decay curve of the all-textured perovskite / silicon heterojunction solar cells prepared in Example 1 and Comparative Example 1 of the present invention before and after continuously operating at the maximum power point for 320 hours at room temperature and 30% humidity.

[0022] Figure 5 is a schematic process flow diagram of the all-textured perovskite / silicon heterojunction solar cell prepared in Example 1 of the present invention.

[0023] As Figure 5As shown, in the first step, an inorganic compound thin film is deposited on the crystalline silicon bottom cell by vacuum method. In the second step, a ternary cationic mixed organic ammonium salt solution of formamidine-guanidine-thiophene-based organic ammonium is coated on the inorganic compound thin film by liquid phase method, so as to in-situ prepare a two-dimensional / three-dimensional perovskite bulk heterojunction on the textured crystalline silicon bottom cell. Detailed implementation manners

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention, but are not used to limit the implementation scope of the present invention.

[0025] Please refer to Figure 1 , which is a full-textured perovskite / crystalline silicon tandem solar cell of the present invention. It sequentially includes a crystalline silicon bottom cell and a perovskite top cell from bottom to top. The crystalline silicon bottom cell is based on a full-textured amorphous silicon / crystalline silicon heterojunction, and the light absorption layer of the perovskite top cell is based on a two-dimensional / three-dimensional perovskite bulk heterojunction. The crystalline silicon bottom cell and the perovskite top cell are connected by a p-type microcrystalline silicon tunneling composite layer (80) with a crystallization rate of 50%.

[0026] Comparative example 1: A full-textured perovskite / crystalline silicon tandem solar cell prepared with pure formamidine hydroiodide organic ammonium salt

[0027] (1) A commercial micron-scale textured intrinsic monocrystalline silicon wafer (resistance 1-3 Ω, 150 microns) is selected. 5 nm of intrinsic amorphous silicon and 10 nm of p-type amorphous silicon are sequentially deposited on the back of the intrinsic monocrystalline silicon wafer through a plasma-enhanced chemical vapor deposition device. Then, 5 nm of intrinsic amorphous silicon and 10 nm of n-type amorphous silicon are sequentially deposited on the front of the intrinsic monocrystalline silicon wafer. Among them, the intrinsic amorphous silicon can be obtained by introducing SiH4 (flow rate 20 sccm) and H2 (flow rate 50 sccm) into the reaction chamber of the device and under the action of plasma. When depositing p-type amorphous silicon, B2H6 (flow rate 20 sccm) gas needs to be additionally introduced. When depositing n-type amorphous silicon, PH3 (flow rate 20 sccm) gas needs to be additionally introduced. Immediately afterwards, a 100 nm back indium tin oxide transparent electrode (mass ratio of indium oxide to tin oxide is 97:3) is deposited on the p-type amorphous silicon on the back of the silicon wafer through a physical vapor deposition device. Then, a 200 nm silver electrode is deposited on the back indium tin oxide transparent electrode by a thermal evaporation vacuum deposition device to obtain the back silver electrode. Finally, a 15 nm p-type microcrystalline silicon tunneling composite layer with a crystallization rate of 50% is deposited on the n-type amorphous silicon on the front of the silicon wafer through a plasma-enhanced chemical vapor deposition device, thus completing the preparation of the crystalline silicon bottom cell;

[0028] (2) In a thermal evaporation vacuum deposition equipment, a hole transport layer of 2,2,7,7 - tetra(N,N - di - p - tolyl)amino - 9,9 - spirobifluorene (spiro - TTB) with a thickness of 25 nm was deposited on the microcrystalline silicon tunneling composite layer at an evaporation rate of 0.02 nm per second. Immediately afterwards, the first step of the vacuum - assisted two - step method for preparing the perovskite light - absorbing layer was carried out: lead iodide and cesium bromide were co - evaporated using the thermal evaporation vacuum deposition equipment, and the gas - phase deposition rate ratio of lead iodide to cesium bromide was controlled at 1:0.08 to obtain an inorganic compound thin film of a mixture of lead iodide and cesium bromide with a total thickness of 400 nm on the hole transport layer;

[0029] (3) An ethanol solution of formamidinium hydroiodide (molar concentration of 0.5 M) was prepared. 200 microliters were measured using a pipette in a glove box and spin - coated on the surface of the inorganic compound thin film prepared in step (2). The rotation speed of the spin coater was 3200 revolutions per minute, and the rotation time was 30 seconds. Subsequently, it was immediately placed on a hot plate at 150 °C in an environment with a relative humidity of 50% and thermally annealed for 30 minutes to obtain a pure three - dimensional perovskite light - absorbing layer. From Figure 2 The scanning electron microscope image of the surface of the perovskite light - absorbing layer thin film in Comparative Example 1 shows that the perovskite grains are small, the surface is rough, and there are many holes.

[0030] (4) Using a thermal evaporation vacuum deposition equipment, a 1 - nm - thick passivation layer of LiF was deposited on the surface of the pure three - dimensional perovskite light - absorbing layer. Immediately afterwards, the thermal evaporation vacuum deposition equipment was continued to be used to deposit a 10 - nm - thick electron transport layer C 60 .

[0031] (5) Using an atomic layer deposition equipment, a 20 - nm - thick SnO2 was deposited on the surface of C 60 as a protective layer. Subsequently, a 100 - nm - thick front - side indium tin oxide transparent electrode (mass ratio of indium oxide to tin oxide is 97:3) was deposited on the surface of SnO2 using a physical vapor deposition method.

[0032] (6) Finally, using a thermal evaporation vacuum deposition equipment, a 200 - nm - thick front - side silver grid line electrode (the grid line electrode consists of a main grid and fine grids. The effective area determined by the main grid is 1 cm 2 , there are 6 fine grids inside the main grid, each fine grid is 7 mm long and evenly distributed inside the main grid) and a 100 - nm - thick antireflection layer of MgF2 were deposited on the indium tin oxide transparent electrode in step (5). From Figure 3 The I - V characteristic curve of the stacked solar cell in Comparative Example 1 under AM1.5G illumination shows that the open - circuit voltage is 1.67 V, the current density is 18 mA / cm 2 , the fill factor is 68%, and the photoelectric conversion efficiency is 20.4%. FromFigure 4 After the stacked solar cell in Comparative Example 1 continuously operated at the maximum power point for 320 hours, the photoelectric conversion efficiency decreased to 15.2%, indicating poor stability.

[0033] Example 1

[0034] An example of a method for simultaneously improving the open-circuit voltage and stability of a full-textured perovskite / silicon heterojunction solar cell, comprising the following steps:

[0035] (1) Select a commercial micro-textured intrinsic monocrystalline silicon wafer (resistance 1 - 3 Ω, 150 μm). Using a plasma-enhanced chemical vapor deposition apparatus, deposit 5 nm of intrinsic amorphous silicon and 10 nm of p-type amorphous silicon on the back of the intrinsic monocrystalline silicon wafer in sequence, and then deposit 5 nm of intrinsic amorphous silicon and 10 nm of n-type amorphous silicon on the front of the intrinsic monocrystalline silicon wafer in sequence. Among them, the intrinsic amorphous silicon can be obtained by introducing SiH4 (flow rate 20 sccm) and H2 (flow rate 50 sccm) into the reaction chamber of the apparatus and under the action of plasma. When depositing p-type amorphous silicon, an additional B2H6 (flow rate 20 sccm) gas needs to be introduced, and when depositing n-type amorphous silicon, an additional PH3 (flow rate 20 sccm) gas needs to be introduced. Immediately afterwards, deposit a 100 nm indium tin oxide transparent electrode on the p-type amorphous silicon on the back of the silicon wafer by physical vapor deposition apparatus (mass ratio of indium oxide to tin oxide is 97:3), and then deposit a 200 nm silver electrode on the indium tin oxide transparent electrode on the back by thermal evaporation vacuum deposition apparatus to obtain the back silver electrode; finally, deposit a 15 nm p-type microcrystalline silicon tunneling composite layer with a crystallization rate of 50% on the n-type amorphous silicon on the front of the silicon wafer by plasma-enhanced chemical vapor deposition apparatus, thereby completing the preparation of the silicon bottom cell. The deposition of the 50% p-type microcrystalline silicon tunneling composite layer uses the introduced gases of SiH4 (flow rate 20 sccm), H2 (flow rate 500 sccm) and B2H6 (flow rate 20 sccm);

[0036] (2) Deposit a 25 nm hole transport layer of 2,2,7,7-tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene (spiro-TTB) on the microcrystalline silicon tunneling composite layer at an evaporation rate of 0.02 nanometers per second in a thermal evaporation vacuum deposition apparatus; immediately afterwards, perform the first step of the vacuum-assisted two-step method for preparing the perovskite light absorption layer: co-evaporate lead iodide and cesium bromide by a thermal evaporation vacuum deposition apparatus, control the gas-phase deposition rate ratio of lead iodide and cesium bromide at 1:0.08, and obtain an inorganic compound film with a total thickness of 400 nm of a mixture of lead iodide and cesium bromide on the hole transport layer;

[0037] (3) Mix formamidine hydroiodide, guanidine hydroiodide, and 2-thiopheneethylamine hydrobromide in a molar ratio of 1:0.05:0.02 and dissolve them in ethanol. The molar concentration of formamidine hydroiodide is 0.5 mol / L to obtain a ternary mixed organic ammonium salt solution. Use a pipette to measure 200 μL of this ternary mixed organic ammonium salt solution in a glove box and spin-coat it on the surface of the inorganic compound film prepared in step (2). The rotation speed of the spin coater is 3200 revolutions per minute, and the rotation time is 30 seconds. Subsequently, immediately place it on a hot plate at 150 °C in an environment with a relative humidity of 50% and perform thermal annealing for 30 minutes to in-situ obtain a two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer. From Figure 2 It can be seen from the scanning electron microscope image of the surface of the perovskite light absorption layer film that the perovskite grains are large and smooth, and layered two-dimensional perovskite can be clearly seen at the grain boundaries of the three-dimensional perovskite.

[0038] (4) Use a thermal evaporation vacuum deposition equipment to deposit a 1-nm-thick passivation layer of LiF on the surface of the two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer. Immediately afterwards, continue to use the thermal evaporation vacuum deposition equipment to deposit a 10-nm-thick electron transport layer of C 60 .

[0039] (5) Use atomic layer deposition equipment to deposit a 20-nm-thick SnO2 on the surface of C 60 as a protective layer. Subsequently, use physical vapor deposition method to deposit a 100-nm-thick front indium tin oxide transparent electrode (the mass ratio of indium oxide to tin oxide is 97:3) on the surface of SnO2.

[0040] (6) Finally, use a thermal evaporation vacuum deposition equipment to deposit a 200-nm-thick front silver grid line electrode (the grid line electrode consists of a main grid and fine grids. The effective area determined by the main grid is 1 cm 2 , the main grid contains 6 fine grids inside, and each fine grid is 7 mm long and evenly distributed inside the main grid) and a 100-nm-thick antireflection layer of MgF2 on the indium tin oxide transparent electrode in step (5). From Figure 3 It can be seen from the I-V characteristic curve of the tandem solar cell in Example 1 under AM1.5G illumination that the open-circuit voltage is 1.8 V, the current density is 20 mA / cm 2 , the fill factor is 75%, and the photoelectric conversion efficiency is 27.0%. Compared with Comparative Example 1, the index parameters of the tandem cell have been significantly improved in all aspects. In addition, from Figure 4 It can be seen that after the tandem solar cell in Example 1 continuously operates at the maximum power point for 320 hours, the photoelectric conversion efficiency still remains above 26.0% with basically no attenuation, indicating that the device stability has been greatly improved.

[0041] The above embodiments are only some preferred embodiments of the present invention, which are only used to illustrate the principles and improvement effects of the present invention and shall not be used to limit the patent protection scope of the present invention. Those of ordinary skill in the art can make various changes, improvements and refinements to the present invention without departing from the spirit and scope of the invention. The additional functions in these improvements can be combined alone or in any way, and these changes, improvements and refinements should also be regarded as within the protection scope of the present invention patent.

Claims

1. A preparation method of a full-textured perovskite / crystalline silicon tandem solar cell for simultaneously improving the open-circuit voltage and stability. The full-textured perovskite / crystalline silicon tandem solar cell is composed of a crystalline silicon bottom cell, a microcrystalline silicon tunneling composite layer, and a perovskite top cell. The perovskite top cell includes a two-dimensional / three-dimensional perovskite bulk heterojunction light absorption layer, and is characterized in that: The two-dimensional / three-dimensional perovskite bulk heterojunction photoabsorber layer is prepared based on the vacuum-assisted two-step method. In the first step, lead iodide and cesium bromide are simultaneously vapor-deposited through a thermal evaporation vacuum deposition device to form an inorganic compound thin film with a uniform mixture of lead iodide and cesium bromide. In the second step, a ternary cationic mixed organic ammonium salt solution of formamidinium, guanidinium, and thiophene-based organic ammonium is coated on the inorganic compound thin film by liquid phase, and a two-dimensional / three-dimensional perovskite bulk heterojunction photoabsorber layer is obtained in-situ through thermal annealing, thereby realizing the preparation of a full-textured perovskite / silicon heterojunction solar cell with both high open-circuit voltage and stability; among them, the ternary cationic mixed organic ammonium salt solution of formamidinium, guanidinium, and thiophene-based organic ammonium is prepared by dissolving formamidinium hydroiodide, guanidinium hydroiodide, and thiophene-based organic ammonium hydrohalide in an ethanol solution and mixing them, and the thiophene-based organic ammonium hydrohalide is 2-thiopheneethylamine hydrobromide or 2-thiopheneethylamine hydrochloride.

2. The preparation method of a fully-textured perovskite / silicon heterojunction solar cell for simultaneously improving open-circuit voltage and stability according to claim 1, characterized in that: The vapor deposition rate ratio of lead iodide and cesium bromide is 1:0.08, and the thickness of the inorganic compound thin film is 300-500 nm.

3. The preparation method of a full-textured perovskite / silicon heterojunction tandem solar cell for simultaneously improving open-circuit voltage and stability as claimed in claim 1, wherein: The ternary cationic mixed organic ammonium salt solution of formamidinium, guanidinium, and thiophene-based organic ammonium is coated on the inorganic compound thin film by liquid phase, and then thermally annealed on a hot stage at 140-160 °C for 20-40 minutes in an environment with a relative humidity of 30-60% to obtain a two-dimensional / three-dimensional perovskite bulk heterojunction photoabsorber layer.

4. The preparation method of a full-textured perovskite / silicon heterojunction tandem solar cell for simultaneously improving open-circuit voltage and stability as claimed in claim 3, wherein: The molar ratio of formamidinium hydroiodide, guanidinium hydroiodide, and thiophene-based organic ammonium hydrohalide is 1:0.05:0.

02.

5. The preparation method of a full-textured perovskite / silicon heterojunction solar cell for simultaneously improving open-circuit voltage and stability as claimed in claim 1, characterized in that: The microcrystalline silicon tunneling composite layer selects p-type microcrystalline silicon with a crystallization rate of 50%.

6. The preparation method of a full-textured perovskite / silicon heterojunction tandem solar cell for simultaneously improving open-circuit voltage and stability according to claim 1, characterized in that: In the order of preparation, the crystalline silicon bottom cell is successively composed of a back silver electrode, a back indium tin oxide transparent electrode, a back p-type amorphous silicon, a back intrinsic amorphous silicon, an intrinsic monocrystalline silicon wafer with a micron-level textured surface, a front intrinsic amorphous silicon, and a front n-type amorphous silicon; the perovskite top cell is successively composed of a hole transport layer spiro-TTB, a two-dimensional / three-dimensional hybrid heterojunction perovskite light absorption layer, a passivation layer LiF, an electron transport layer C 60 , a protective layer SnO2, a front indium tin oxide transparent electrode, a front silver grid line electrode, and an antireflection layer MgF2.

7. The preparation method of a full-textured perovskite / silicon heterojunction tandem solar cell for simultaneously improving the open-circuit voltage and stability according to claim 6, wherein: Hole transport layer spiro-TTB, passivation layer LiF, electron transport layer C 60 , the antireflection layer MgF2, the front silver grid line electrode and the back silver electrode are deposited by a thermal evaporation vacuum deposition device, the protective layer SnO2 is deposited by an atomic layer deposition device, and the back and front indium tin oxide transparent electrodes are deposited by a physical vapor deposition device. The back and front intrinsic amorphous silicon, the back p-type amorphous silicon, the front n-type amorphous silicon, and the microcrystalline silicon tunneling composite layer are prepared by plasma enhanced chemical vapor deposition.

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