Interlayer structure for solar cell and preparation method and application thereof

Abstract

The invention provides an interlayer structure for a solar cell and a preparation method and application thereof, and the interlayer structure for the solar cell comprises a transparent conductive oxide layer, a hole transport layer and a perovskite absorption layer. The hole transport layer includes a self-assembled monomolecular hole transport layer material and trifluoroacetate co-deposited on a transparent conductive oxide. Based on the interlayer structure for the solar cell, the problems of low photoelectric conversion efficiency and poor stability of a perovskite solar cell in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and in particular, to an intermediate layer structure for solar cells, a preparation method thereof, and an application thereof. Background Art

[0002] As an emerging photovoltaic technology, perovskite solar cells have attracted extensive attention globally since their inception due to their excellent photoelectric conversion efficiency and low-cost manufacturing process. Perovskite materials, with their unique crystal structure and excellent optoelectronic properties such as broad spectral absorption, high photogenerated carrier mobility, and long diffusion length, show great potential to become the next-generation solar cell materials. Laboratory studies have shown that the efficiency of perovskite / silicon tandem solar cells has far exceeded that of traditional silicon-based solar cells. However, during the transition to large-scale practical applications, perovskite solar cells still face many technical challenges, especially their long-term stability and interface engineering problems. In perovskite solar cells, interface defects, especially those at the buried interface, have a crucial impact on the optoelectronic performance and stability of the devices. These interface defects not only lead to non-radiative recombination losses, thereby reducing the photoelectric conversion efficiency of the cells, but may also cause material degradation, affecting the long-term service life of the devices. Therefore, reducing the buried interface defects of the perovskite layer is of great significance for improving the photoelectric conversion efficiency and stability of perovskite solar cells. Summary of the Invention

[0003] The main object of the present invention is to provide an intermediate layer structure for solar cells, a preparation method thereof, and an application thereof, so as to solve the problems of low photoelectric conversion efficiency and poor stability of perovskite solar cells in the prior art.

[0004] To achieve the above object, according to one aspect of the present invention, there is provided an intermediate layer structure for solar cells, including: a transparent conductive oxide layer, a hole transport layer, and a perovskite absorption layer, wherein the hole transport layer includes a self-assembled monolayer hole transport layer material and a trifluoroacetate co-deposited on the transparent conductive oxide.

[0005] Further, the trifluoroacetate includes one or more of sodium trifluoroacetate, potassium trifluoroacetate, cesium trifluoroacetate, methylammonium trifluoroacetate, and formamidinium trifluoroacetate.

[0006] Further, the self-assembled monolayer hole transport layer material includes one or more of 2PACz, 4PACz, MeO-2PACz, Me-4PACz, and Me-2PACz.

[0007] Further, the transparent conductive oxide layer material includes one or more of ITO, FTO, IZO, AZO, and IZrO.

[0008] Further, the weight ratio of the self-assembled single-molecule hole transport layer material to the trifluoroacetate in the hole transport layer is (1 to 2):(1 to 2).

[0009] Further, the thickness of the hole transport layer is 1 nm to 10 nm.

[0010] Further, the thickness of the transparent conductive oxide layer is 5 nm to 20 nm.

[0011] Further, the thickness of the perovskite absorption layer is 500 nm to 1.5 μm.

[0012] Further, the perovskite absorption layer material is Cs x FA y MA 1-x-y Pb(I a Br b Cl 1-a-b ) 3 ; wherein, 0 < x < 1, 0 < y < 1, 0 ≤ a < 1, 0 ≤ b < 1.

[0013] According to another aspect of the present invention, there is provided a method for preparing the intermediate layer structure for a solar cell as described above, comprising the following steps:

[0014] Step S1, coating a coating solution containing a self-assembled single-molecule hole transport layer material and trifluoroacetate on the transparent conductive oxide layer by a coating method, and then annealing at 80°C to 120°C for 5 min to 15 min to form a hole transport layer;

[0015] Step S2, preparing a perovskite absorption layer on the hole transport layer by a coating method to obtain an intermediate layer structure for a solar cell.

[0016] Further, the transparent conductive oxide layer is prepared by physical vapor deposition (PVD), atomic layer deposition (ALD) or radio frequency sputtering deposition (RPD).

[0017] Further, the perovskite absorption layer is prepared on the hole transport layer by slot coating, spin coating, blade coating or spraying.

[0018] Further, a perovskite precursor solution is coated on the hole transport layer by a coating method, and then annealed at 100°C to 160°C for 5 min to 10 min to obtain a perovskite absorption layer; the solvent of the perovskite precursor solution is selected from one or both of DMF and DMSO.

[0019] Further, before coating the coating solution containing the self-assembled single-molecule hole transport layer material and trifluoroacetate, step S1 further includes a step of performing ultraviolet ozone treatment on the transparent conductive oxide layer.

[0020] Further, the solvent of the coating solution containing the self-assembled monolayer hole transport layer material is ethanol.

[0021] Further, in the coating solution containing the self-assembled monolayer hole transport layer material and trifluoroacetate, the concentration of trifluoroacetate is 0.5 mg / L to 1 mg / L, and the concentration of the self-assembled monolayer hole transport layer material is 0.5 mg / L to 1 mg / L.

[0022] According to another aspect of the present invention, there is provided an application of the intermediate layer structure for a solar cell as described above, for the preparation of a single-junction perovskite solar cell, a perovskite / perovskite tandem solar cell, or a perovskite / silicon tandem solar cell.

[0023] According to still another aspect of the present invention, there is provided a perovskite / silicon tandem solar cell, which includes a silicon bottom cell, the intermediate layer structure for a solar cell as described above, an interface passivation layer, an electron transport layer, a buffer layer, a transparent electrode layer, and a metal electrode layer that are sequentially stacked. On the silicon cell, a transparent conductive oxide layer, a hole transport layer, a perovskite absorption layer, an interface passivation layer, an electron transport layer, a buffer layer, a transparent electrode layer, and a metal electrode layer are sequentially stacked.

[0024] Further, the silicon bottom cell is a TOPCon cell or a silicon-based heterojunction cell.

[0025] Further, the interface passivation layer material includes one or more of phenethylammonium iodide (PEAI), phenethylammonium chloride (PEACl), oleylamine iodide (OAI), ethylenediamine iodide (EDADI), propylenediamine iodide (PDADI), LiF, and MgF 2 and the like.

[0026] Further, the electron transport layer material includes one or two of C 60 and PCBM.

[0027] Further, the buffer layer material includes one or two of SnO 2 and BCP.

[0028] Further, the transparent electrode layer material includes one or more of ITO, FTO, IZO, AZO, and IZrO.

[0029] Further, the metal electrode layer material includes one or more of Ag, Au, Cu, and Al.

[0030] Applying the technical solution of the present invention, using trifluoroacetate as an interfacial modification material, depositing trifluoroacetate and a self-assembled monolayer hole transport layer material on a transparent conductive oxide layer by co-deposition to form a hole transport layer, can regulate the nucleation and growth process of subsequent perovskite at the interface, promote the growth of the perovskite absorption layer, enhance the contact between the buried bottom interface of the perovskite absorption layer and the transparent conductive oxide layer (TCO layer), reduce the defect density, improve the perovskite crystallization quality, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell; in addition, trifluoroacetate can also optimize the arrangement of the self-assembled monolayer hole transport layer material, enhance its hole transport performance, and further improve the photoelectric conversion efficiency of the perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0032] Figure 1 shows a schematic diagram of a perovskite / silicon heterojunction solar cell based on an embodiment of the present invention; and

[0033] Figure 2 shows a SEM image of the contact interface between the perovskite absorption layer and the transparent conductive oxide layer of the perovskite / silicon heterojunction solar cell in Example 1;

[0034] Figure 3 shows a SEM image of the contact interface between the perovskite absorption layer and the transparent conductive oxide layer of the perovskite / silicon heterojunction solar cell in Comparative Example 1.

[0035] Among them, the above-mentioned drawings include the following reference numerals:

[0036] 1, silicon bottom cell; 2, transparent conductive oxide layer; 3, hole transport layer; 4, perovskite absorption layer; 5, interfacial passivation layer; 6, electron transport layer; 7, buffer layer; 8, transparent electrode layer; 9, metal electrode layer; 10, antireflection layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0038] As described in the background art, there are problems of low photoelectric conversion efficiency and poor stability of perovskite solar cells in the prior art. To solve the above problems, as Figure 1As shown in the figure, the present invention provides an intermediate layer structure for a solar cell, comprising: a transparent conductive oxide layer 2, a hole transport layer 3, and a perovskite absorption layer 4. The hole transport layer 3 comprises a self-assembled monolayer hole transport layer material and a trifluoroacetate co-deposited on the transparent conductive oxide.

[0039] Based on the intermediate layer structure for a solar cell of the present invention, using trifluoroacetate as an interface modification material, depositing the trifluoroacetate and the self-assembled monolayer hole transport layer material on the transparent conductive oxide layer by co-deposition to form a hole transport layer can regulate the subsequent nucleation and growth process of perovskite at the interface, promote the growth of the perovskite absorption layer, enhance the contact between the buried bottom interface of the perovskite absorption layer and the transparent conductive oxide layer (TCO layer), reduce the defect density, improve the perovskite crystallization quality, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell; in addition, the trifluoroacetate can also optimize the arrangement of the self-assembled monolayer hole transport layer material, enhance its hole transport performance, and further improve the photoelectric conversion efficiency of the perovskite solar cell.

[0040] In some embodiments, the trifluoroacetate comprises one or more of sodium trifluoroacetate, potassium trifluoroacetate, cesium trifluoroacetate, methylammonium trifluoroacetate, and formamidinium trifluoroacetate. Using the above trifluoroacetates can effectively improve the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0041] In some embodiments, the self-assembled monolayer hole transport layer material comprises one or more of 2PACz, 4PACz, MeO-2PACz, Me-4PACz, Me-2PACz, including but not limited to the above materials. Other carbazole phosphoric acid type hole transport layer materials capable of providing phosphonic acid groups are also applicable to the present invention. The above self-assembled monolayer hole transport layer material containing phosphonic acid groups can self-assemble on the transparent conductive oxide layer 2 to form a closely arranged ordered monolayer, with few film-forming defect states and good quality, and has high-efficiency charge extraction ability.

[0042] In some embodiments, the material of the transparent conductive oxide layer 2 comprises one or more of ITO, FTO, IZO, AZO, IZrO, but is not limited to the above materials.

[0043] In some embodiments, the weight ratio of the self-assembled monolayer hole transport layer material to the trifluoroacetate in the hole transport layer 3 is (1-2):(1-2). When the weight ratio of the self-assembled monolayer hole transport layer material to the trifluoroacetate is within the above range, it is beneficial to reduce the defects of the perovskite absorption layer 4, improve the crystallization quality of the perovskite absorption layer 4, improve the carrier transport and collection efficiency, and ultimately improve the photoelectric conversion efficiency of the perovskite solar cell; moreover, the reduction of interface defects and the improvement of the perovskite absorption layer quality contribute to enhancing the long-term stability of the perovskite solar cell.

[0044] In some embodiments, the thickness of the hole transport layer 3 is 1 nm to 10 nm. Using the hole transport layer 3 with the above thickness is beneficial to the collection and transport of holes, and is also beneficial to the nucleation and growth process of perovskite at the interface, enhancing the contact between the perovskite bottom interface and the substrate, reducing the defect density, and improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0045] In some embodiments, in order to obtain higher photoelectric conversion efficiency and stability, the thickness of the transparent conductive oxide layer 2 is 5 nm to 20 nm.

[0046] In some embodiments, in order to obtain higher photoelectric conversion efficiency and stability, the thickness of the perovskite absorption layer 4 is 5 nm to 1.5 μm. In some embodiments, the material of the perovskite absorption layer 4 includes Cs x FA y MA 1-x-y Pb(I a Br b Cl 1-a-b ) 3 ; wherein, 0 < x < 1, 0 < y < 1, 0 ≤ a < 1, 0 ≤ b < 1. The above-mentioned organic-inorganic hybrid perovskite structure Cs x FA y MA 1-x-y Pb(I a Br b Cl 1-a-b ) 3 , has a relatively high photoelectric conversion efficiency, and for the perovskite absorption layer 4 containing Cs x FA y MA 1-x-y Pb(I a Br b Cl 1-a-b ) 3 material, the carboxyl group and cation in the trifluoroacetate can also respectively inhibit the formation of Pb 2+ and I - defects with insufficient coordination in the perovskite absorption layer 4, and stabilize the organic cations at the bottom interface through the strong hydrogen bond between the organic cations (FA + , MA + ) in the perovskite absorption layer 4 and the F atoms in the trifluoroacetate, which is beneficial to obtaining a high-quality perovskite absorption layer, inhibiting non-radiative recombination, and further improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0047] According to another aspect of the present invention, there is provided a method for preparing the intermediate layer structure for a solar cell as described above, including the following steps:

[0048] Step S1: Coating a coating solution containing a self-assembled monolayer hole transport layer material and trifluoroacetate on the transparent conductive oxide layer by a coating method, and then annealing at 80 °C to 120 °C for 5 min to 15 min to form a hole transport layer;

[0049] Step S2: Preparing a perovskite absorption layer on the hole transport layer by a coating method to obtain an intermediate layer structure for a solar cell.

[0050] Using the method of the present invention to prepare an intermediate layer structure for a solar cell can obtain a high solar power conversion efficiency, and the preparation process is simple, efficient, low-cost, and easy for large-scale production.

[0051] In some embodiments, the transparent conductive oxide layer is prepared by physical vapor deposition (PVD), atomic layer deposition (ALD), or radio frequency sputtering deposition (RPD).

[0052] In some embodiments, the perovskite absorption layer is prepared on the hole transport layer by slot coating, spin coating, blade coating, or spraying. By using the above slot coating, spin coating, blade coating, or spraying techniques, a uniform and dense perovskite absorption layer can be obtained, which is beneficial to improving the light absorption efficiency, reducing non-radiative recombination, and thus enhancing the photoelectric conversion efficiency and stability of the battery.

[0053] In some embodiments, a perovskite precursor solution is coated on the hole transport layer by a coating method, and then annealed at 100 °C to 160 °C for 5 min to 10 min to obtain a perovskite absorption layer; the solvent of the perovskite precursor solution is selected from one or both of DMF and DMSO. Under the above annealing treatment conditions and solvent conditions, it is beneficial to obtain a perovskite absorption layer with high crystal quality.

[0054] In some embodiments, before coating the coating solution containing the self-assembled monolayer hole transport layer material and trifluoroacetate, step S1 further includes a step of performing ultraviolet ozone treatment on the transparent conductive oxide layer. Performing ultraviolet ozone treatment on the transparent conductive oxide layer can clean the surface, remove organic pollutants, and at the same time form a thin oxide layer on the surface of the TCO layer, which is beneficial to improving the interfacial bonding with the self-assembled monolayer hole transport layer material and the trifluoroacetate material, promoting their adsorption and the self-assembly of the self-assembled monolayer hole transport layer material. It is beneficial to reduce the interfacial defects between the TCO layer and the hole transport layer, reduce the recombination loss of carriers at the interface, and enhance the photoelectric conversion efficiency and long-term stability of the perovskite solar cell.

[0055] In some embodiments, the solvent of the coating solution containing the self-assembled monolayer hole transport layer material is ethanol. Selecting ethanol as the solvent is beneficial for the formation of a uniform and dense self-assembled monolayer of the self-assembled monolayer hole transport layer material on the substrate. Such a layer can effectively transport holes and reduce non-radiative recombination, improving the carrier transport efficiency between the perovskite layer and the transparent conductive oxide layer (TCO layer), thereby enhancing the overall photoelectric conversion efficiency of the battery. Moreover, ethanol as the solvent is beneficial for the dissolution and uniform deposition of trifluoroacetates such as sodium trifluoroacetate, facilitating the uniform growth of the perovskite absorption layer and improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0056] In some embodiments, in the coating solution containing the self-assembled monolayer hole transport layer material and trifluoroacetate, the concentration of trifluoroacetate is 0.5 mg / L to 1 mg / L, and the concentration of the self-assembled monolayer hole transport layer material is 0.5 mg / L to 1 mg / L. Using trifluoroacetate and the self-assembled monolayer hole transport layer material at the above concentrations is beneficial for the uniform co-deposition of trifluoroacetate and the self-assembled monolayer hole transport layer material on the transparent conductive oxide layer, forming a stable and uniform interface for the uniform growth of the perovskite absorption layer, and improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0057] According to another aspect of the present invention, there is provided an application of the intermediate layer structure for a solar cell as described above, for the preparation of a single-junction perovskite solar cell, a perovskite / perovskite tandem solar cell, or a perovskite / silicon tandem solar cell.

[0058] According to still another aspect of the present invention, there is provided a perovskite / silicon tandem solar cell, which includes a silicon bottom cell 1, the intermediate layer structure for a solar cell as described above, an interface passivation layer 5, an electron transport layer 6, a buffer layer 7, a transparent electrode layer 8, and a metal electrode layer 9 that are sequentially stacked. On the silicon cell, a transparent conductive oxide layer 2, a hole transport layer 3, a perovskite absorption layer 4, an interface passivation layer 5, an electron transport layer 6, a buffer layer 7, a transparent electrode layer 8, and a metal electrode layer 9 are sequentially stacked. The perovskite / silicon tandem solar cell has become the mainstream in photovoltaics. Using trifluoroacetate as an interface modification material can regulate the nucleation and growth process of perovskite at the interface, promote the bottom-up growth of the perovskite absorption layer, enhance the contact between the buried bottom interface of the perovskite and the transparent conductive oxide layer 2, reduce the defect density, and improve the photoelectric conversion efficiency and stability of the perovskite / silicon tandem solar cell. In some embodiments, the silicon bottom cell 1 is a TOPCon cell or a silicon-based heterojunction cell.

[0059] In some embodiments, the interface passivation layer 5 material includes PEAI, PEACl, OAI, EDADI, PDADI, LiF, MgF 2One or more of the above, but not limited to the above materials; preferably, the thickness of the interface passivation layer 5 is 1 nm to 3 nm. Specifically, methods such as spraying, spin coating, doctor blading, evaporation coating, etc. can be used to prepare the interface passivation layer 5.

[0060] In some embodiments, the material of the electron transport layer 6 includes one or two of C 60 , PCBM, but not limited to the above materials; preferably, the thickness of the electron transport layer 6 is 5 nm to 30 nm. Specifically, methods such as spin coating, spraying, evaporation coating, etc. can be used to prepare the electron transport layer 6.

[0061] In some embodiments, the material of the buffer layer 7 includes one or two of SnO 2 , BCP, but not limited to the above materials; preferably, the thickness of the buffer layer 7 is 5 nm to 30 nm. Specifically, methods such as ALD, PVD, RPD, evaporation coating, etc. can be used to prepare the buffer layer 7.

[0062] In some embodiments, the material of the transparent electrode layer 8 includes one or more of ITO, FTO, IZO, AZO, IZrO, but not limited to the above materials; preferably, the thickness of the transparent electrode layer 8 is 10 nm to 100 nm. Specifically, methods such as PVD, ALD, RPD, etc. can be used to prepare the transparent electrode layer 8.

[0063] In some embodiments, the material of the metal electrode layer 9 includes one or more of Ag, Au, Cu, Al, but not limited to the above materials; preferably, the thickness of the metal electrode layer 9 is 100 nm to 1 μm. Specifically, methods such as PVD, evaporation coating, screen printing, etc. can be used to prepare the metal electrode layer 9.

[0064] In some embodiments, an antireflection layer 10 is provided on the metal electrode layer 9, and the material of the antireflection layer 10 includes one or more of MgF 2 , LiF, SiN x , but not limited to the above materials; preferably, the thickness of the antireflection layer 10 is 100 nm to 200 nm. Specifically, methods such as evaporation coating, CVD, etc. can be used to prepare the antireflection layer 10.

[0065] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0066] Example 1

[0067] A perovskite / crystalline silicon tandem solar cell includes a crystalline silicon heterojunction bottom cell, a first ITO layer, a hole transport layer, a perovskite absorption layer, a PEAI layer, a PCBM layer, SnO 2 layer, a second ITO layer, an Ag electrode layer, MgF 2Layer; wherein, the hole transporting layer comprises 2PACz and sodium trifluoroacetate co-deposited on the transparent conductive oxide; the thickness of the first ITO layer is 15 nm, the thickness of the hole transporting layer is 3 nm, the thickness of the perovskite absorption layer is 1 μm, the thickness of the PEAI layer is 1 nm, the thickness of the PCBM layer is 5 nm, and the thickness of the SnO 2 layer is 20 nm, the thickness of the second ITO layer is 80 nm, and the thickness of the Ag electrode layer is 1 μm, and the thickness of the MgF 2 layer is 100 nm.

[0068] The preparation steps of the perovskite / silicon heterojunction tandem solar cell are as follows:

[0069] Step 1, prepare the first ITO layer on the silicon heterojunction bottom cell by physical vapor deposition; Step 2, perform ultraviolet ozone treatment on the first ITO layer for 10 min, and then spin-coat the coating solution containing 2PACz and sodium trifluoroacetate onto the first ITO layer, and then anneal at 100 °C for 10 min to obtain the hole transporting layer; wherein, the solvent in the coating solution containing 2PACz and sodium trifluoroacetate is ethanol, the concentration of sodium trifluoroacetate is 0.8 mg / L, and the concentration of 2PACz is 0.8 mg / L;

[0070] Step 3: Weigh CsI, FAI, MABr, PbBr, and PbI according to the stoichiometric ratio 2 and add them to the organic solvent, stir for 3 h to obtain Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 perovskite precursor solution, spin-coat the perovskite precursor solution onto the hole transporting layer, and then anneal at 100 °C for 8 min to obtain the perovskite absorption layer Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 ; wherein, the organic solvent is obtained by mixing DMF and DMSO in a volume ratio of 4:1;

[0071] Step 4, prepare the PEAI layer on the perovskite layer by evaporation technology;

[0072] Step 5, prepare the PCBM layer on the PEAI layer by spin-coating;

[0073] Step 6, deposit the SnO 2 layer on the PCBM layer by atomic layer deposition (ALD);

[0074] Step 7, prepare the second ITO layer on the SnO 2 layer by physical vapor deposition;

[0075] Step VIII: Use screen printing to sequentially prepare an Ag electrode layer on the second ITO layer;

[0076] Step IX: Use evaporation technology to prepare a MgF 2 layer on the prepared Ag electrode layer.

[0077] Example 2

[0078] A perovskite / crystalline silicon tandem solar cell includes a crystalline silicon heterojunction bottom cell, a first FTO layer, a hole transport layer, a perovskite absorption layer, a PEAI layer, a PCBM layer, a SnO 2 layer, a second FTO layer, an Ag electrode layer, and a MgF 2 layer, which are sequentially stacked from bottom to top; wherein, the hole transport layer includes 4PACz and potassium trifluoroacetate co-deposited on a transparent conductive oxide; the thickness of the first FTO layer is 5 nm, the thickness of the hole transport layer is 1 nm, the thickness of the perovskite absorption layer is 500 nm, the thickness of the PEAI layer is 1 nm, the thickness of the PCBM layer is 5 nm, the thickness of the SnO 2 layer is 20 nm, the thickness of the second FTO layer is 80 nm, the thickness of the Ag electrode layer is 1 μm, and the thickness of the MgF 2 layer is 100 nm.

[0079] The preparation steps of the perovskite / crystalline silicon tandem solar cell are as follows:

[0080] Step I: Use physical vapor deposition to prepare a first FTO layer on the crystalline silicon heterojunction bottom cell;

[0081] Step II: Perform ultraviolet ozone treatment on the first FTO layer for 10 min, then use spin coating to coat a coating solution containing 4PACz and potassium trifluoroacetate onto the first FTO layer, and then anneal at 100°C for 10 min to obtain a hole transport layer; wherein, the solvent in the coating solution containing 4PACz and potassium trifluoroacetate is ethanol, the concentration of potassium trifluoroacetate is 0.5 mg / L, and the concentration of 4PACz is 1 mg / L;

[0082] Step III: Weigh CsI, FAI, MABr, PbBr, and PbI 2 according to the stoichiometric ratio and add them to an organic solvent, stir for 3 h to obtain a Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 perovskite precursor solution, use spin coating to coat the perovskite precursor solution onto the hole transport layer, and then anneal at 100°C for 8 min to obtain a perovskite absorption layer Cs 0.05 FA 0.8MA 0.15 PbI 0.75 Br 0.25 ; wherein, the organic solvent is obtained by mixing DMF and DMSO in a volume ratio of 4:1;

[0083] Step Four, prepare the PEAI layer on the perovskite layer by using evaporation coating technology;

[0084] Step Five, prepare the PCBM layer on the PEAI layer by using spin coating;

[0085] Step Six, deposit the SnO 2 layer on the PCBM layer by using atomic layer deposition (ALD);

[0086] Step Seven, prepare the second FTO layer on the SnO 2 layer by using physical vapor deposition;

[0087] Step Eight, prepare the Ag electrode layer on the second FTO layer in sequence by using screen printing;

[0088] Step Nine, prepare the MgF 2 layer on the prepared Ag electrode layer by using evaporation coating technology.

[0089] Example 3

[0090] A perovskite / crystalline silicon tandem solar cell, comprising a crystalline silicon heterojunction bottom cell, a first IZO layer, a hole transport layer, a perovskite absorption layer, a PEAI layer, a PCBM layer, a SnO 2 layer, a second IZO layer, an Ag electrode layer, and a MgF 2 layer, which are sequentially stacked from bottom to top; wherein, the hole transport layer includes MeO-2PACz and methylammonium trifluoroacetate co-deposited on the transparent conductive oxide; the thickness of the first IZO layer is 20 nm, the thickness of the hole transport layer is 10 nm, the thickness of the perovskite absorption layer is 1.5 μm, the thickness of the PEAI layer is 1 nm, the thickness of the PCBM layer is 5 nm, the thickness of the SnO 2 layer is 20 nm, the thickness of the second IZO layer is 80 nm, the thickness of the Ag electrode layer is 1 μm, and the thickness of the MgF 2 layer is 100 nm.

[0091] The preparation steps of the perovskite / crystalline silicon tandem solar cell are as follows:

[0092] Step One, prepare the first IZO layer on the crystalline silicon heterojunction bottom cell by using physical vapor deposition;

[0093] Step 2: Perform ultraviolet ozone treatment on the first IZO layer for 10 min, then spin-coat a coating solution containing MeO-2PACz and methylammonium trifluoroacetate onto the first IZO layer, and then anneal at 100 °C for 10 min to obtain a hole transport layer; wherein, the solvent in the coating solution containing MeO-2PACz and methylammonium trifluoroacetate is ethanol, the concentration of methylammonium trifluoroacetate is 1 mg / L, and the concentration of MeO-2PACz is 0.5 mg / L;

[0094] Step 3: Weigh CsI, FAI, MABr, PbBr, and PbI according to the stoichiometric ratio 2 Add them to an organic solvent and stir for 3 h to obtain Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 perovskite precursor solution, spin-coat the perovskite precursor solution onto the hole transport layer, and then anneal at 100 °C for 8 min to obtain a perovskite absorption layer Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 ; wherein, the organic solvent is obtained by mixing DMF and DMSO in a volume ratio of 4:1;

[0095] Step 4: Prepare a PEAI layer on the perovskite layer by vapor deposition technology;

[0096] Step 5: Prepare a PCBM layer on the PEAI layer by spin-coating;

[0097] Step 6: Deposit a SnO 2 layer on the PCBM layer by atomic layer deposition (ALD);

[0098] Step 7: Prepare a second IZO layer on the SnO 2 layer by physical vapor deposition;

[0099] Step 8: Prepare an Ag electrode layer on the second IZO layer by screen printing in sequence;

[0100] Step 9: Prepare a MgF 2 layer on the prepared Ag electrode layer by vapor deposition technology.

[0101] Example 4

[0102] The difference from Example 1 is only that in the coating solution containing 2PACz and sodium trifluoroacetate, the concentration of sodium trifluoroacetate is 1 mg / L and the concentration of 2PACz is 0.5 mg / L.

[0103] Example 5

[0104] The difference from Example 1 is only that in the coating solution containing 2PACz and sodium trifluoroacetate, the concentration of sodium trifluoroacetate is 2 mg / L and the concentration of 2PACz is 0.2 mg / L.

[0105] Example 6

[0106] The difference from Example 1 is only that in the coating solution containing 2PACz and sodium trifluoroacetate, the concentration of sodium trifluoroacetate is 0.2 mg / L and the concentration of 2PACz is 2 mg / L.

[0107] Comparative Example 1

[0108] The difference from Example 1 is only that the coating solution in Step 2 does not contain sodium trifluoroacetate, specifically as follows:

[0109] A perovskite / crystalline silicon tandem solar cell includes a crystalline silicon heterojunction bottom cell, a first ITO layer, a hole transport layer, a perovskite absorption layer, a PEAI layer, a PCBM layer, a SnO 2 layer, a second ITO layer, an Ag electrode layer, and an MgF 2 layer, which are stacked in sequence from bottom to top; wherein, the hole transport layer includes 2PACz deposited on a transparent conductive oxide; the thickness of the first ITO layer is 15 nm, the thickness of the hole transport layer is 3 nm, the thickness of the perovskite absorption layer is 1 μm, the thickness of the PEAI layer is 1 nm, the thickness of the PCBM layer is 5 nm, the thickness of the SnO 2 layer is 20 nm, the thickness of the second ITO layer is 80 nm, the thickness of the Ag electrode layer is 1 μm, and the thickness of the MgF 2 layer is 100 nm.

[0110] The preparation steps of the perovskite / crystalline silicon tandem solar cell are as follows:

[0111] Step 1, preparing the first ITO layer on the crystalline silicon heterojunction bottom cell by physical vapor deposition;

[0112] Step 2, performing ultraviolet ozone treatment on the first ITO layer for 10 min, then spin-coating the coating solution containing 2PACz onto the first ITO layer, and then annealing at 100 °C for 10 min to obtain the hole transport layer; wherein, the solvent in the coating solution containing 2PACz and sodium trifluoroacetate is ethanol, and the concentration of 2PACz is 0.8 mg / L;

[0113] Step 3: Weigh CsI, FAI, MABr, PbBr, and PbI according to the stoichiometric ratio 2 and add them to an organic solvent, and stir for 3 h to obtain Cs 0.05 FA 0.8MA 0.15 PbI 0.75 Br 0.25 A perovskite precursor solution was spin-coated onto the hole transport layer, and then annealed at 100 °C for 8 min to obtain a perovskite absorption layer Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 ; wherein, the organic solvent is obtained by mixing DMF and DMSO in a volume ratio of 4:1;

[0114] Step four, a PEAI layer was prepared on the perovskite layer by vapor deposition;

[0115] Step five, a PCBM layer was prepared on the PEAI layer by spin coating;

[0116] Step six, SnO was deposited on the PCBM layer by atomic layer deposition (ALD) 2 layer;

[0117] Step seven, a second ITO layer was prepared on the SnO 2 layer by physical vapor deposition;

[0118] Step eight, an Ag electrode layer was sequentially prepared on the second ITO layer by screen printing;

[0119] Step nine, a MgF was prepared on the prepared Ag electrode layer by vapor deposition 2 layer.

[0120] Comparative Example 2

[0121] The difference from Example 1 is only that in step two, 2PACz and sodium trifluoroacetate were successively deposited on the first ITO layer, specifically as follows:

[0122] A perovskite / silicon heterojunction tandem solar cell includes a silicon heterojunction bottom cell, a first ITO layer, a hole transport layer, an interface modification layer, a perovskite absorption layer, a PEAI layer, a PCBM layer, SnO 2 layer, a second ITO layer, an Ag electrode layer, and a MgF 2 layer, which are stacked in sequence from bottom to top; wherein, the hole transport layer includes 2PACz deposited on a transparent conductive oxide; the interface modification layer includes sodium trifluoroacetate deposited on the hole transport layer; the thickness of the first ITO layer is 15 nm, the thickness of the hole transport layer is 1.5 nm, the thickness of the interface modification layer is 1.5 nm, the thickness of the perovskite absorption layer is 1 μm, the thickness of the PEAI layer is 1 nm, the thickness of the PCBM layer is 5 nm, and the thickness of SnO 2The thickness of the first ITO layer is 20 nm, the thickness of the second ITO layer is 80 nm, the thickness of the Ag electrode layer is 1 μm, and the thickness of the MgF 2 layer is 100 nm.

[0123] The preparation steps of the perovskite / crystalline silicon tandem solar cell are as follows:

[0124] Step 1: Prepare the first ITO layer on the crystalline silicon heterojunction bottom cell by physical vapor deposition;

[0125] Step 2: Perform ultraviolet ozone treatment on the first ITO layer for 10 min, then spin-coat the coating solution containing 2PACz onto the first ITO layer, and then anneal at 100 °C for 5 min to obtain the hole transport layer; then spin-coat the coating solution containing sodium trifluoroacetate onto the hole transport layer, and then anneal at 100 °C for 5 min to obtain the interface modification layer; wherein, the solvent in the coating solution containing 2PACz and sodium trifluoroacetate is ethanol, the concentration of 2PACz is 0.8 mg / L; the solvent in the coating solution containing sodium trifluoroacetate is ethanol, and the concentration of sodium trifluoroacetate is 0.8 mg / L;

[0126] Step 3: Weigh CsI, FAI, MABr, PbBr and PbI 2 according to the stoichiometric ratio and add them to an organic solvent, stir for 3 h to obtain Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 perovskite precursor solution, spin-coat the perovskite precursor solution onto the hole transport layer, and then anneal at 100 °C for 8 min to obtain the perovskite absorption layer Cs 0.05 FA 0.8 MA 0.15 PbI 0.75 Br 0.25 ; wherein, the organic solvent is obtained by mixing DMF and DMSO in a volume ratio of 4:1;

[0127] Step 4: Prepare the PEAI layer on the perovskite layer by evaporation technology;

[0128] Step 5: Prepare the PCBM layer on the PEAI layer by spin-coating;

[0129] Step 6: Deposit the SnO 2 layer on the PCBM layer by atomic layer deposition (ALD);

[0130] Step 7: Prepare the second ITO layer on the SnO 2 layer by physical vapor deposition;

[0131] Step 8: Prepare an Ag electrode layer on the second ITO layer by screen printing;

[0132] Step 9: Prepare MgF on the prepared Ag electrode layer by evaporation technology 2 layer.

[0133] Performance Test

[0134] 1. Use a scanning electron microscope to perform SEM characterization on the contact interface between the perovskite absorption layer and the transparent conductive oxide layer (i.e., the first ITO layer, the hole transport layer is too thin to be observed) of Example 1 and Comparative Example 1. The results are respectively as Figure 2 and Figure 3 shown. By comparison, it can be seen that the buried bottom interface on the side of the perovskite absorption layer close to the transparent conductive oxide layer in Example 1 is regular, and there are few gaps and close contact between the perovskite absorption layer and the transparent conductive oxide layer.

[0135] 2. Test the performance of the perovskite / silicon heterojunction solar cells prepared in the examples and comparative examples. The photoelectric conversion efficiency (PCE), fill factor (FF), open circuit voltage (Voc), and short circuit current (Jsc) are shown in Table 1.

[0136] 3. Test respectively (test conditions: air environment with a temperature of 25°C and a humidity of 30%, AM1.5G light illumination condition), the PCE retention rate of the perovskite / silicon heterojunction solar cells prepared in the examples and comparative examples after 500h is shown in Table 1 respectively.

[0137] Table 1

[0138] Voc (V) <![CDATA[Jsc (mA / cm 2 )]]> FF (%) PCE (%) PCE retention rate Example 1 1.902 20.02 79.8 30.39 85.8％ Example 2 1.882 19.99 78.1 29.38 84.2％ Example 3 1.913 20.05 79.5 30.49 85.5％ Example 4 1.899 19.97 80.3 30.45 85.3％ Example 5 1.893 19.84 78.8 29.60 84.5％ Example 6 1.887 19.81 78.2 29.23 84.6％ Comparative Example 1 1.873 19.49 74.2 27.09 71.1％ Comparative Example 2 1.868 19.45 73.9 26.85 70.6％

[0139] As can be seen from Table 1, compared with Comparative Example 1 and Comparative Example 2, Examples 1-6 introduce a co-deposited self-assembled monolayer hole transport layer material and trifluoroacetate co-deposition between the transparent conductive oxide layer and the perovskite absorption layer. The obtained perovskite / silicon heterojunction solar cells have higher open circuit voltage, short circuit current density and fill factor, and higher photoelectric conversion efficiency and PCE retention rate.

[0140] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An intermediate layer structure for a solar cell, characterized in that: include: A transparent conductive oxide layer, a hole transport layer and a perovskite absorption layer, wherein the hole transport layer comprises a self-assembled monomolecular hole transport layer material and trifluoroacetate co-deposited on the transparent conductive oxide.

2. The intermediate layer structure for solar cells according to claim 1, characterized in that: The trifluoroacetate includes one or more of sodium trifluoroacetate, potassium trifluoroacetate, cesium trifluoroacetate, methylamine trifluoroacetate, and formamidine trifluoroacetate; and / or, The self-assembled monomolecular hole transport layer material includes one or more of 2PACz, 4PACz, MeO-2PACz, Me-4PACz, and Me-2PACz; and / or, The transparent conductive oxide layer material includes one or more of ITO, FTO, IZO, AZO, and IZrO.

3. The intermediate layer structure for solar cells according to claim 1 or 2, characterized in that: The weight ratio of the self-assembled monomolecular hole transport layer material and the trifluoroacetate in the hole transport layer is (1-2): (1-2); and / or, The thickness of the hole transport layer is 1 nm to 10 nm; and / or, The thickness of the transparent conductive oxide layer is 5 nm to 20 nm; and / or, The thickness of the perovskite absorption layer is 500nm-1.5μm.

4. The intermediate layer structure for solar cells according to claim 1 or 2, characterized in that: The perovskite absorption layer material is Cs x FA y MA 1-x-y Pb(I a Br b Cl 1-a-b )3; where 0<x<1, 0<y<1, 0≤a<1, 0≤b<1.

5. A method for preparing an intermediate layer structure for a solar cell according to any one of claims 1 to 4, characterized in that: The steps include: Step S1, coating a coating solution containing a self-assembled monomolecular hole transport layer material and trifluoroacetate on the transparent conductive oxide layer by a coating method, and then annealing at 80° C. to 120° C. for 5 min to 15 min to form a hole transport layer; Step S2, preparing a perovskite absorption layer on the hole transport layer by a coating method to obtain the intermediate layer structure for the solar cell.

6. The method for preparing an intermediate layer structure for a solar cell according to claim 5, characterized in that: The transparent conductive oxide layer is prepared by physical vapor deposition (PVD), atomic layer deposition (ALD) or radio frequency sputtering deposition (RPD); and / or, The perovskite absorption layer is prepared on the hole transport layer by slit coating, spin coating, blade coating or spray coating; and / or, A perovskite precursor solution is coated on the hole transport layer by a coating method, and then annealed at 100° C. to 160° C. for 5 to 10 minutes to obtain the perovskite absorption layer; the solvent of the perovskite precursor solution is selected from one or both of DMF and DMSO.

7. The method for preparing an intermediate layer structure for a solar cell according to claim 5 or 6, characterized in that: Before coating the self-assembled monomolecular hole transport layer material, the step S1 further comprises a step of treating the transparent conductive oxide layer with ultraviolet ozone; and / or, The solvent of the coating solution containing the material of the self-assembled monomolecular hole transport layer is ethanol; and / or, In the coating solution containing the self-assembled monomolecular hole transport layer material and trifluoroacetate, the concentration of the trifluoroacetate is 0.5 mg / L to 1 mg / L, and the concentration of the self-assembled monomolecular hole transport layer material is 0.5 mg / L to 1 mg / L.

8. Use of the intermediate layer structure for solar cells according to any one of claims 1 to 4, characterized in that: Used for the preparation of single-cell perovskite solar cells, perovskite / perovskite tandem solar cells or perovskite / crystalline silicon tandem solar cells.

9. A perovskite / crystalline silicon tandem solar cell, characterized in that: The perovskite / crystalline silicon stacked solar cell comprises a crystalline silicon bottom cell, an intermediate layer structure for a solar cell according to any one of claims 1 to 4, an interface passivation layer, an electron transport layer, a buffer layer, a transparent electrode layer, and a metal electrode layer, which are stacked in sequence, and a transparent conductive oxide layer, a hole transport layer, a perovskite absorption layer, the interface passivation layer, the electron transport layer, the buffer layer, the transparent electrode layer, and the metal electrode layer are stacked in sequence on the crystalline silicon cell.

10. The perovskite / crystalline silicon tandem solar cell according to claim 9, characterized in that: The crystalline silicon bottom cell is a TOPCon cell or a silicon-based heterojunction cell; and / or, The interface passivation layer material includes one or more of PEAI, PEACl, OAI, EDADI, PDADI, LiF, and MgF2; and / or, The electron transport layer material includes C 60 , one or both of PCBM; and / or, The buffer layer material includes one or two of SnO2 and BCP; and / or, The transparent electrode layer material includes one or more of ITO, FTO, IZO, AZO, and IZrO; and / or the metal electrode layer material includes one or more of Ag, Au, Cu, and Al.

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