Organic-inorganic perovskite light absorption layer, perovskite solar cell and preparation method

Abstract

The invention provides an organic-inorganic perovskite light absorption layer, a perovskite solar cell and respective preparation methods, the light absorption layer adopts three-source co-evaporation to form an inorganic material layer, then the inorganic material layer is coated with an organic ammonium salt, cesium halide and lead chloride are introduced in the preparation method, a large-framework CsPb2X5 (X = Cl / Br / I) quasi-two-dimensional layered structure is formed in the inorganic layer, and the perovskite solar cell is prepared. The distance between crystal surfaces in the inorganic framework is enlarged, and permeation of an organic ammonium salt solution is promoted. The content of the lead chloride is controlled by regulating the deposition rate of the lead chloride so as to form gradient distribution, so that energy level alignment of the light absorption layer and the hole transport layer is realized, and the efficiency of the perovskite solar cell is improved.

Description

Technical Field

[0001] The invention relates to an organic-inorganic perovskite light-absorbing layer, a solar cell containing the light-absorbing layer and a preparation method, and belongs to the field of solar energy. Background Art

[0002] Perovskite / silicon tandem solar cells have been widely studied because of their theoretical conversion efficiency far exceeding that of silicon cells. The high-efficiency or large-area monolithic perovskite / silicon tandems reported so far are mainly fabricated on silicon bottom cells, with the front side being polished or submicron textured (pyramid size is usually less than 1 μm) to accommodate the solution process for depositing perovskite films. However, this requires adding redundant polishing steps or pyramid size modifications to the established standard industrial process, and has poor light management relative to industrial textured silicon. Therefore, seeking perovskite preparation methods compatible with industrial textured silicon will help achieve strong light management at a lower cost.

[0003] The evaporation-solution two-step method is to form a conformally grown perovskite absorber on the pyramid by reacting the evaporated inorganic metal salt precursor with the spin-coated organic salt. The perovskite prepared by this method can utilize fully textured silicon wafers and is compatible with the current silicon industrialization route. However, the lack of strong interfacial chemical bonds and van der Waals gaps in perovskites hinders the further penetration of organic salts, resulting in insufficient consumption of inorganic precursors and uneven formation of perovskites from bottom to top, which limits device performance. In addition, more bromine in wide-bandgap perovskites will also lead to halogen phase separation in the film, forming a low-bandgap iodine-rich phase and a high-bandgap bromine-rich phase, causing more defects in the perovskite film, which in turn affects the performance of silicon / perovskite stacked solar cells. Summary of the invention

[0004] In order to solve the problem that the spin-coated organic salt in the evaporation-solution method is not easy to penetrate into the evaporated inorganic material layer, thereby causing a low degree of reaction of the inorganic precursor, the present invention provides a method for preparing an organic-inorganic perovskite light-absorbing layer. In the preparation method, by introducing cesium halide and lead chloride, a large-skeleton CsPb2X5 (X=Cl / Br / I) quasi-two-dimensional layered structure is formed in the inorganic layer, the crystal plane spacing in the inorganic framework is expanded, and the penetration of the organic ammonium salt solution is promoted.

[0005] The technical solution adopted by the present invention is: a method for preparing an organic-inorganic perovskite light absorbing layer, comprising the following steps:

[0006] A first evaporation source PbI2, a second evaporation source CsX, and a third evaporation source PbCl2 are co-evaporated on the substrate to form an evaporation layer, wherein X is a halogen, and CsX can be one, two, or three of CsI, CsCl, and CsBr;

[0007] After the evaporation is completed, an organic ammonium salt solution is applied to the surface of the evaporation layer, wherein the organic ammonium salt solution contains methylamine ions and / or formamidine ions, and the organic ammonium salt is immersed in the evaporation layer to react with the evaporation layer material;

[0008] Annealing to form a perovskite light-absorbing layer.

[0009] As a preferred solution, the evaporation rates of the first evaporation source and the second evaporation source are constant, and the evaporation rate of the third evaporation source decreases steadily over time.

[0010] As a preferred solution, the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source is 1:0.1-1:0.2; preferably, the evaporation rate of the first evaporation source is The evaporation rate of the second evaporation source is

[0011] As a preferred embodiment, the initial evaporation rate of the third evaporation source is The evaporation rate at the end is The evaporation rate decreases uniformly during the evaporation process. Preferably, the thickness of the perovskite inorganic material layer is 400-600 nm.

[0012] As a preferred embodiment, the second evaporation source is CsBr or CsI, more preferably the second evaporation source is CsBr, the organic ammonium salt is FAX (formamidinium halide) or MAX (methyl ammonium halide), X is a halogen, preferably at least two of formamidinium iodide (FAI), formamidinium bromide (FABr), methylammonium iodide (MAI), methylammonium bromide (MABr), and methylammonium chloride (MACl), more preferably containing FAI and FABr, and the molar ratio of the two is FAI:FABr=(4:1)~(1:4).

[0013] One side of the perovskite light absorbing layer is a hole transport layer, and the other side is an electron transport layer. The perovskite light absorbing layer is deposited on the hole transport layer, and the deposition rate of the third evaporation source gradually decreases from the hole transport layer side to the electron transport layer side.

[0014] In a second aspect, the present invention provides an organic-inorganic perovskite light-absorbing layer, wherein the light-absorbing layer contains a substance with an ABX3 perovskite structure, wherein an A1 ion and an A2 ion are arranged at the A position, wherein the A1 ion is Cs + , A2 ion is methylamine ion or formamidine ion, and B position is Pb 2+ , X position is I - or Br - or Cl - , where Cl -The content of gradually decreases from the side close to the hole transport layer to the side close to the electron transport layer. The light absorbing layer makes the bottom band gap of the perovskite larger than the top band gap by means of the gradient distribution of lead chloride, constructs a gradient perovskite absorber, optimizes the energy level alignment between the perovskite and the hole transport layer, and promotes the hole transport layer to extract current. The light absorbing layer can be prepared by adopting the scheme of Cl- gradient distribution that can be formed in the preparation method of the above-mentioned organic-inorganic perovskite light absorbing layer.

[0015] In a third aspect, the present invention provides a method for preparing a solar cell containing a perovskite light absorbing layer, comprising the following steps:

[0016] (1) obtaining a substrate. If the substrate is a silicon-calcium stacked cell, the substrate is a crystalline silicon cell, and directly or indirectly depositing a hole transport layer on the light-absorbing surface of the crystalline silicon cell;

[0017] (2) directly or indirectly depositing a perovskite light absorbing layer on the hole transport layer;

[0018] (3) directly or indirectly depositing an electron transport layer on the perovskite light absorbing layer;

[0019] (4) directly or indirectly depositing an electrode on the electron transport layer;

[0020] The preparation method of the perovskite light absorbing layer is:

[0021] A first evaporation source PbI2, a second evaporation source CsX, and a third evaporation source PbCl2 are co-evaporated on the substrate to form an inorganic material layer, wherein the evaporation rate of the third evaporation source gradually decreases over time;

[0022] After the evaporation is completed, an organic ammonium salt solution is coated on the surface of the evaporation layer, wherein the organic ammonium salt solution contains FAX and / or MAX, and the organic ammonium salt is immersed in the inorganic material layer to react with the substance in the inorganic material layer. It is worth noting that X in CsX, FAX, and MAX can be the same or different, but are all selected from I - , Cl - Br - .

[0023] (5) Annealing to form a perovskite light-absorbing layer.

[0024] The indirect deposition mentioned above is deposition after other film layers are separated. For example, the indirect deposition of the perovskite light absorbing layer on the hole transport layer can be: depositing the modified film layer, passivation layer or transition layer on the hole transport layer and then depositing the perovskite light absorbing layer. Direct deposition is the deposition of the perovskite light absorbing layer directly on the hole transport layer without passing through other film layers.

[0025] As a preferred embodiment, the hole transport layer material is MeO-2PACz ([2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), Me-4PACz ((4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), 4PADCB ((4-(7h-dibenzo[c,g]carbazole-7-yl)butyl)phosphonic acid), nickel oxide (NiO x ) or a combination of one or more thereof.

[0026] As a preferred embodiment, the materials of the electron transport layer are tin dioxide (SnO2), [6,6]-phenyl C61 butyric acid methyl ester (PC 61 BM), carbon 60 (C 60 ), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) or a combination of one or more thereof.

[0027] As a preferred scheme, an electron transport layer is deposited after a passivation layer is deposited on the perovskite light-absorbing layer, and the passivation layer material is ethylenediamine dihydroiodide (EDAI2), including but not limited to at least one of phenethylammonium iodide (PEAI), phenethylammonium chloride (PEACl), propylenediamine bromide (PDADBr), butylammonium iodide (BAI), and piperazine iodate (PI).

[0028] As a preferred solution, the electrode is deposited after a buffer layer is deposited on the electron transport layer, and the buffer layer is a combination of one or more of tin oxide (SnO2), titanium dioxide (TiO2), and zinc oxide (ZnO).

[0029] As a preferred solution, the evaporation rates of the first evaporation source and the second evaporation source are consistent, and the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source is 1:0.1-1:0.2; preferably, the evaporation rate of the first evaporation source is The evaporation rate of the second evaporation source is

[0030] As a preferred embodiment, the initial evaporation rate of the third evaporation source is The evaporation rate is 0 at the end, and the evaporation rate decreases uniformly during the evaporation process.

[0031] As a preferred solution, the second evaporation source is CsBr or CsI, and the organic ammonium salt includes FAI and FABr, and the molar ratio of the two is FAI:FABr=(4:1) to (1:4).

[0032] As a preferred solution, the thickness of the inorganic material layer is 400-600 nm.

[0033] As a preferred solution, one side of the perovskite light-absorbing layer is a hole transport layer, and the other side is an electron transport layer. The light-absorbing layer is deposited on the hole transport layer, and the deposition rate of the third evaporation source gradually decreases from the hole transport layer side to the electron transport layer side.

[0034] In a fourth aspect, the present invention provides a solar cell containing a perovskite light-absorbing layer, the solar cell containing the light-absorbing layer in the second aspect, preferably prepared by any method in the perovskite solar cell in the third aspect. The perovskite solar cell can be a single-junction, silicon-calcium stacked cell. If it is a silicon-calcium stacked cell, the substrate is a crystalline silicon cell, and a hole transport layer, a perovskite film layer, an electron transport layer and an electrode layer are coated on the light-absorbing surface of the crystalline silicon cell.

[0035] The beneficial effects of the present invention include: (1) PbCl2 can react with PbI2 and CsBr to expand the crystal plane spacing in the inorganic framework and promote the penetration of organic ammonium salt solution. At the same time, the porosity of the buried bottom surface of the machine frame is greater than that of the upper surface, which is conducive to eliminating residual PbI2.

[0036] (2) The addition of chloride ions can regulate the band gap of perovskite and offset the adverse effects of bromine on perovskite films;

[0037] (3) The gradient evaporation of PbCl2 makes the bottom band gap of the perovskite larger than the top band gap, constructing a gradient perovskite absorber, which can optimize the energy level alignment between the perovskite and the hole transport layer and promote the current extraction of the hole transport layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A curve diagram showing the relationship between the evaporation rate of the inorganic phase evaporation source and time in Example 1;

[0039] Figure 2 A curve diagram showing the relationship between the evaporation rate of the inorganic phase evaporation source and time in Example 2;

[0040] Figure 3 The structure diagram of the silicon-perovskite tandem battery in Example 3;

[0041] Figure 4 A curve diagram showing the relationship between the evaporation rate of the inorganic phase evaporation source and time in Comparative Example 1;

[0042] Figure 5 A curve diagram showing the relationship between the evaporation rate of the inorganic phase evaporation source and time in Comparative Example 2;

[0043] Figure 6 JV curves of the stacked batteries in Example 3, Example 4, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION

[0044] The embodiments of the present invention will be described in detail below, but it should not be understood that the protection scope of the present invention is limited by the following content. Unless otherwise specified, any range recorded in the present invention includes any end value and any numerical value between the end values ​​and any sub-range constituted by the end value or any numerical value between the end values. All raw materials of the present invention are not particularly limited to their purity, and the present invention preferably adopts analytical pure. All raw materials of the present invention, their sources and abbreviations all belong to conventional sources and abbreviations in this area, and are clear and definite in the field of their related uses. Those skilled in the art can purchase or prepare them from commercially available methods according to the abbreviations and corresponding uses. All percentages of the present invention are molar percentages unless otherwise specified, and the solution is solvent with isopropanol unless otherwise specified.

[0045] "At least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b, c can be single or plural.

[0046] When preparing wide bandgap perovskite cells, PbI2 is required for the light absorption layer, but PbI2 has a dense structure. After the evaporation is completed, it is difficult for the organic ammonium salt solution to penetrate into the evaporation layer, resulting in incomplete reaction of the bottom PbI2. In order to solve this problem, the present invention adopts a three-source co-evaporation method to introduce the second evaporation source CsX, the third evaporation source PbCl2 and the first evaporation source PbI2 to form an inorganic material layer. The addition of Cs can regulate the crystallization of PbI2, making it loose and porous, thereby reducing the difficulty of the organic ammonium salt solution infiltrating the inorganic material layer. The addition of PbCl2 forms a quasi-two-dimensional layered structure of CsPb2X5 in the inorganic material layer, where X is Cl or I or Br. The formation of this structure produces an enlarged crystal plane spacing in the inorganic framework, which can promote the organic ammonium salt solution to penetrate into the inorganic material layer and fully react with it.

[0047] The perovskite light absorbing layer in the present invention is prepared by the following method:

[0048] S01 uses a three-source co-evaporation method to form an evaporation layer on the substrate. The first evaporation source is PbI2, the second evaporation source is CsX, and the third evaporation source is PbCl2. CsX can be one, two or three of CsI, CsBr, and CsCl. During the evaporation process, the evaporation rates of the first evaporation source and the second evaporation source are preferably unchanged, and the evaporation rate of the third evaporation source decreases from fast to slow, and the evaporation amount gradually decreases. On the one hand, this method can form more CsPb2X5 (X=Cl / Br / I) quasi-two-dimensional layered structures in the bottom layer, expand the spacing between inorganic layers, and facilitate the penetration of organic ammonium salts to the bottom. On the other hand, the content of PbCl2 is in a step-by-step transition state, which is conducive to achieving energy level matching between the light absorption layer and the hole transport layer.

[0049] After the S02 evaporation is completed, an inorganic material layer is formed on the substrate, and an organic ammonium salt solution is coated on the inorganic material layer, which can be spin coating or slit coating. The organic ammonium salt solution penetrates into the inorganic material layer and reacts with the inorganic material to form a perovskite structure. As a preferred method, the organic ammonium salt is selected from formamidine hydroiodide (FAI), formamidine hydrobromide (FABr), methylammonium iodide (MAI), methylamine hydrobromide (MABr), and methylammonium chloride (MACl). In order to obtain a perovskite light-absorbing layer with a band gap width of 1.6-1.8 eV, the organic ammonium salt must contain FAI and FABr. Once again, the molar ratio of FAI to FABr is FAI:FABr=(4:1)~(1:4).

[0050] The organic ammonium salt solution of the present invention contains FAI, FABr, and solute a, wherein the solute a represents one, two or more solutes, and can be (1) a single solute: MAI or MABr or MACl, (2) a mixture of two solutes: MAI and MABr, or MABr and MACl, or MAI and MACl, or (3) a mixture of three solutes: MAI, MABr and MACl. However, the above conditions all need to meet the following requirements: in terms of molar amount, the amount of solute a accounts for 0% to 50% of the total amount of FAI and FABr; the solvent of the organic ammonium salt is one or a combination of anhydrous ethanol and isopropanol, and the solute concentration in the solution is 0.5 to 2M.

[0051] S03 annealing to obtain a light absorbing layer.

[0052] In step S01, the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source is 1:0.1-1:0.2. By controlling the evaporation rate, the doping amount of the two substances can be controlled. On the one hand, the evaporation rate can form a wide band gap perovskite light absorption layer of 1.6eV-1.8eV, and on the other hand, a small amount of Cs can be added to make the inorganic material layer structure loose. In order to further optimize the quality of the evaporated film layer, the evaporation rate of the first evaporation source is The evaporation rate of the second evaporation source is

[0053] The initial evaporation rate of the third evaporation source in the present invention is Then it decreases gradually to The initial evaporation rate can be When the evaporation is finished, the evaporation rate is reduced to 0. This evaporation method is conducive to forming a gradient PbCl2 content, so that the porosity of the buried surface of the inorganic material layer is greater than that of the surface, and on the other hand, it can form a gradual band gap, which is conducive to the extraction of carriers.

[0054] If the organic ammonium salt solution is spin-coated in step S02, the spin-coating speed is 1000-5000 rpm and the spin-coating time is 10-50 s. After the spin-coating, annealing is performed at a temperature of 130-160°C and a time of 10-30 min. If slit coating is used, the conditions are as follows: N2 in air is used as an auxiliary and the temperature is 20 mm s -1 The blade is coated with 100 μL of organic salt solution at a rate of ; the gap between the blade and the substrate is 80-250 μm, and the pressure of the N2 blade is 30 PSI. After coating, annealing is performed under air conditions for 10-30 minutes at a temperature of 130-160°C.

[0055] When the light absorbing layer is completed, the thickness of the light absorbing layer is 400-600nm.

[0056] The method for preparing the silicon-perovskite tandem solar cell of the present invention comprises the following steps:

[0057] S01 obtains a substrate, which is a crystalline silicon cell, and can be HJT, HBC, TOPCon, etc.

[0058] S02 deposits a hole transport layer on the light-absorbing surface of the crystalline silicon cell. The deposition method can be solution coating (spin coating, scraping, spraying) or vacuum evaporation. The hole transport layer material is MeO-2PACz ([2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), Me-4PACz ((4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), 4PADCB ((4-(7h-dibenzo[c,g]carbazole-7-yl)butyl)phosphonic acid) or nickel oxide (NiO x ) or a combination of one, two or more thereof. S03 depositing a perovskite material on the hole transport layer to form a perovskite light absorbing layer (light absorbing layer), and the deposition method is an evaporation-solution two-step method. The evaporation is a vacuum evaporation method, and the solution method can be a spin coating method, a coating method, a spray coating method, etc., and a perovskite light absorbing layer with a band gap of 1.6eV-1.8eV is prepared by the above method; the specific preparation method of the perovskite light absorbing layer is the above-mentioned preparation method of the light absorbing layer.

[0059] S04 deposits a modification layer material on the perovskite light-absorbing layer to form a passivation layer. The deposition method is coating, which can be scraping, spin coating, spraying, etc.; the modification material can be ethylenediamine dihydroiodide (EDAI2), including but not limited to at least one of phenethylammonium iodide (PEAI), phenethylammonium chloride (PEACl), propylenediamine bromide (PDADBr), butylammonium iodide (BAI), and piperazine iodate (PI).

[0060] (5) Depositing an electron transport layer on the passivation layer by coating or vacuum evaporation. The electron transport layer material includes but is not limited to at least one of tin dioxide (SnO2), titanium dioxide (TiO2), [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), carbon 60 (C60), and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). (6) Depositing a buffer layer on the electron transport layer, the buffer layer material includes but is not limited to one of tin oxide (SnO2), titanium dioxide (TiO2), and zinc oxide (ZnO). The deposition method can be one of atomic layer deposition (ALD), vacuum evaporation, and magnetron sputtering.

[0061] (7) Depositing TCO material on the buffer layer to form a transparent electrode layer, which may be ITO or IZO, and the deposition method may be magnetron sputtering or vacuum evaporation.

[0062] (8) A metal electrode layer is deposited on the transparent electrode, which may be at least one of copper (Cu), silver (Ag), and gold (Au), and the deposition method is vacuum evaporation.

[0063] The perovskite cell produced by this method can avoid the phenomenon of halogen separation in the perovskite light-absorbing layer, make the bottom band gap of the perovskite larger than the top band gap, construct a gradient absorber, optimize the energy level alignment between the perovskite and the hole transport layer, and promote carrier transport.

[0064] The following is a further detailed description in the form of specific embodiments.

[0065] Example 1

[0066] The method for preparing the perovskite light absorbing layer in this embodiment comprises the following steps:

[0067] (1) Evaporation of inorganic salts: A thermal evaporation process is used to form a perovskite inorganic material layer on the substrate. In this embodiment, a three-source co-evaporation process is used, where the first material source is PbI2, the second material source is CsBr, and the third material is PbCl2. During the evaporation process, the evaporation rate of PbI2 remains constant with the evaporation rate of CsBr. The evaporation rate of PbI2 is The evaporation rate of CsBr is The evaporation rate of PbCl2 is kept constant and decelerated throughout the coating process, from the set maximum rate value to the set minimum rate value. During the evaporation process, the maximum rate of PbCl2 is The minimum rate is The total thickness of the perovskite inorganic material layer is 600nm, and the total evaporation time is 1220s. The relationship curve between the evaporation rate and time of PbI2, CsBr and PbCl2 is shown in Figure 1 shown.

[0068] (2) Preparation of organic ammonium salt solution: a mixed solution of MAX and FAX was prepared, wherein MAX includes MABr and MACl, and FAX includes FAI and FABr. The concentration of FAI in the organic ammonium salt solution is 0.318 M, the concentration of FABr is 0.120 M, the concentration of MABr is 0.212 M, and the concentration of MACl is 0.082 M. The solvent is isopropanol.

[0069] (3) Organic ammonium salt coating: This process is carried out in a glove box by spin coating. The prepared organic ammonium salt solution is spin coated on the inorganic material layer at a spin coating rate of 2000 rpm and a spin coating time of 30 s.

[0070] (4) Annealing the film layer obtained after coating in air with an air humidity of 35-40%, an annealing temperature of 160° C., and a time of 15 min, and obtaining a perovskite light-absorbing layer after cooling.

[0071] Example 2

[0072] The method for preparing the perovskite light absorbing layer in this embodiment comprises the following steps:

[0073] (1) Evaporation of inorganic salts: A thermal evaporation process is used to form a perovskite inorganic material layer on the substrate. In this embodiment, a three-source co-evaporation process is used, where the first material source is PbI2, the second material source is CsBr, and the third material is PbCl2. The evaporation rates of PbI2, CsBr, and PbCl2 remain constant, and the evaporation rate of PbI2 is The evaporation rate of CsBr is The evaporation rate of PbCl2 is The total thickness of the perovskite inorganic material layer is 600nm, and the total evaporation time is 1220s. The relationship curve between the evaporation rate and time of PbI2, CsBr and PbCl2 is shown in Figure 2 shown.

[0074] (2) Preparation of organic ammonium salt solution: a mixed solution of MAX and FAX was prepared, wherein MAX includes MABr and MACl, and FAX includes FAI and FABr. The concentration of FAI in the organic ammonium salt solution is 0.318 M, the concentration of FABr is 0.120 M, the concentration of MABr is 0.212 M, and the concentration of MACl is 0.082 M. The solvent is isopropanol.

[0075] (3) Organic ammonium salt coating: This process is carried out in a glove box by spin coating. The prepared organic ammonium salt solution is spin coated on the inorganic material layer at a spin coating rate of 2000 rpm and a spin coating time of 30 s.

[0076] (4) Annealing the film layer obtained after coating in air with an air humidity of 35-40%, an annealing temperature of 160° C., and a time of 15 min, and obtaining a perovskite light-absorbing layer after cooling.

[0077] Example 3 - Silicon-Perovskite Tandem Cell

[0078] The method for preparing the stacked solar cell in this embodiment is as follows:

[0079] (1) Get the bottom battery

[0080] HJT battery is used as the bottom battery. The parameters of the HJT bottom battery used are as follows: open circuit voltage (V oc ) is 0.70~0.74V, short-circuit current (J sc ) is 38~39.5mA / cm 2 , fill factor (FF) is 80-85%, and photoelectric conversion efficiency (PCE) is 24-25%. The size of the bottom cell is 3cm*3cm. The n-side of the bottom cell is plated with ITO tunnel junction, and the back side is provided with Ag grid line as electrode. The prepared bottom cell is placed in the UV ozone treatment device for 15 minutes for standby use.

[0081] (2) Preparation of hole transport layer

[0082] The hole transport layer material of the present application embodiment takes 4PADCB as an example, and the preparation method is as follows: a. 0.5 mg of 4PADCB is mixed with 1 mL of ethanol solution to obtain a 0.5 mg / mL 4PADCB solution, and a 0.45 μm filter element is used to filter to remove large particles, and the filtered solution is used for standby;

[0083] b. Spin-coat the filtered solution onto the bottom cell at a rate of 4000 rpm for 30 s.

[0084] c Annealed at 120 °C for 20 min to obtain a 4PADCB hole transport layer.

[0085] (3) Preparation of perovskite light absorbing layer

[0086] The perovskite light absorbing layer was prepared on the hole transport layer by using the preparation method of the perovskite light absorbing layer in Example 1.

[0087] (4) Preparation of passivation layer

[0088] a. Preparation of passivation layer solution: In this example, EDAI2 (ethylenediamine dihydroiodide) is used as the passivation layer material. EDAI2 is prepared into a solution with a concentration of 0.5 mg / mL and dissolved under ultrasonic vibration for 30 minutes.

[0089] b The EDAI2 solution was spin coated on the perovskite light-absorbing layer at a speed of 4000 rpm for 30 s, and then annealed in a glove box at 100 °C for 1 min.

[0090] (5) Preparation of electron transport layer

[0091] C was deposited by evaporation 60 As the electron transport layer. The evaporation rate is The film thickness is 15nm.

[0092] (6) Preparation of buffer layer:

[0093] In this example, an atomic layer deposition device (ALD) is used to prepare SnO2 as a buffer layer. The sources are tetrakis dimethylaminotin (tdma-sn) and deionized water. The thickness of SnO2 is 20 nm.

[0094] (7) Preparation of transparent electrodes

[0095] IZO was prepared as a transparent electrode on the buffer layer by magnetron sputtering, and the control power was 500W. The thickness of IZO was 30nm.

[0096] (8) Preparation of electrodes

[0097] A 200nm thick Ag gate line was deposited on the transparent electrode by evaporation method as an electrode.

[0098] The silicon-perovskite stacked cell is prepared, and the structure is as follows Figure 3 shown.

[0099] Example 4 - Silicon-Perovskite Tandem Cell

[0100] The preparation method of the stacked battery in this embodiment is:

[0101] (1) Get the bottom battery

[0102] HJT battery is used as the bottom battery. The parameters of the HJT bottom battery used are as follows: open circuit voltage (V oc ) is 0.70~0.74V, short-circuit current (Jsc ) is 38~39.5mA / cm 2 , fill factor (FF) is 80-85%, and photoelectric conversion efficiency (PCE) is 24-25%. The size of the bottom cell is 3cm*3cm. The n-side of the bottom cell is plated with ITO tunnel junction, and the back side is provided with Ag electrode. The prepared bottom cell is placed in a UV ozone treatment device for 15 minutes for standby use.

[0103] (2) Preparation of hole transport layer

[0104] The hole transport layer material in the embodiment of the present application is 4PADCB as an example, and the preparation method is as follows:

[0105] a. Mix 0.5 mg of 4PADCB with 1 mL of ethanol solution to obtain a 0.5 mg / mL 4PADCB solution, and filter it with a 0.45 μm filter element to remove large particles. The filtered solution is used for later use;

[0106] b. Spin-coat the filtered solution onto the bottom cell at a rate of 4000 rpm for 30 s.

[0107] c Annealed at 120 °C for 20 min to obtain a 4PADCB hole transport layer.

[0108] (3) Preparation of perovskite light absorbing layer

[0109] The perovskite light absorbing layer was prepared on the hole transport layer by using the preparation method of the perovskite light absorbing layer in Example 2.

[0110] (4) Preparation of passivation layer

[0111] a. Preparation of passivation layer solution: In this example, EDAI2 (ethylenediamine dihydroiodide) is used as the passivation layer material. EDAI2 is prepared into a solution with a concentration of 0.5 mg / mL and dissolved under ultrasonic vibration for 30 minutes.

[0112] b The EDAI2 solution was spin coated on the perovskite light-absorbing layer at a speed of 4000 rpm for 30 s, and then annealed in a glove box at 100 °C for 1 min.

[0113] (5) Preparation of electron transport layer

[0114] C was evaporated on the passivation layer by evaporation method. 60 , the evaporation rate is The thickness of the electron transport layer is 15 nm.

[0115] (6) Preparation of buffer layer

[0116] In this example, an atomic layer deposition device (ALD) is used to prepare SnO2 as a buffer layer. The sources are tetrakis dimethylaminotin (tdma-sn) and deionized water. The thickness of SnO2 is 20 nm.

[0117] (7) Preparation of transparent electrodes

[0118] The IZO material was prepared on the buffer layer as a transparent electrode by magnetron sputtering, and the control power was 500 W. The thickness of IZO was 30 nm.

[0119] (8) Preparation of electrodes

[0120] A 200nm thick Ag gate line was deposited on the transparent electrode by evaporation method as an electrode.

[0121] A silicon-perovskite tandem cell was produced.

[0122] Example 5 - Silicon-Perovskite Tandem Cell

[0123] The difference between this embodiment and embodiment 3 is that the preparation method of the perovskite light absorbing layer in step (3) is different, mainly because the concentrations of the second evaporation source and the organic amine salt solution used are different. The preparation method of the perovskite light absorbing layer in this embodiment is:

[0124] (1) Evaporation of inorganic salt: three sources are co-evaporated, the first evaporation source 1 is PbI2, and the evaporation rate is The second evaporation source 2 is CsI, and the evaporation rate is The third evaporation source 3 is PbCl2. The evaporation rate of PbCl2 is kept constant and decelerated during the entire coating process, from the set maximum rate value to the set minimum rate value. During the evaporation process, the maximum rate of PbCl2 is The minimum rate is The total thickness of the inorganic material layer is 500 nm, and the total evaporation time is 1220 s.

[0125] (2) Preparation of organic ammonium salt solution: a mixed solution of MAX and FAX is prepared, wherein MAX is MACl, FAX includes FAI and FABr, the concentration of FAI in the organic ammonium salt solution is 0.110 M, the concentration of FABr is 0.404 M, the concentration of MACl is 0.096 M, and the solvent is isopropanol.

[0126] (3) Organic ammonium salt coating: This process is carried out in a glove box by spin coating. The prepared organic ammonium salt solution is spin coated on the inorganic material layer at a spin coating rate of 2000 rpm and a spin coating time of 30 s.

[0127] (4) Annealing the film layer obtained after coating in air with an air humidity of 35-40%, an annealing temperature of 160° C., and a time of 15 min, and obtaining a perovskite light-absorbing layer after cooling.

[0128] Example 6 - Silicon-Perovskite Tandem Cell

[0129] The difference between this embodiment and embodiment 3 is that the preparation method of the perovskite light absorbing layer in step (3) is different, mainly due to the different evaporation rates of the selected evaporation sources. The preparation method of the perovskite light absorbing layer in this embodiment is: evaporation of inorganic salt: using a thermal evaporation process to make a perovskite inorganic material layer on a substrate. In this embodiment, a three-source co-evaporation process is used, the first material source is PbI2, the second material source is CsBr, and the third material is PbCl2. During the evaporation process, the evaporation rate of PbI2 remains constant with the evaporation rate of CsBr, and the evaporation rate of PbI2 is The evaporation rate of CsBr is The evaporation rate of PbCl2 is kept constant and decelerated throughout the coating process, from the set maximum rate value to the set minimum rate value. During the evaporation process, the maximum rate of PbCl2 is The minimum rate is The total thickness of the perovskite inorganic material layer is 400 nm. (2) Prepare an organic ammonium salt solution: prepare a mixed solution of MAX and FAX, wherein MAX is MACl, FAX includes FAI and FABr, the concentration of FAI in the organic ammonium salt solution is 0.110 M, the concentration of FABr is 0.404 M, the concentration of MACl is 0.096 M, and the solvent is ethanol. The solvent is ethanol.

[0130] (3) Organic ammonium salt coating: This process is carried out in a glove box by spin coating. The prepared organic ammonium salt solution is spin coated on the inorganic material layer at a spin coating rate of 2000 rpm and a spin coating time of 30 s.

[0131] (4) Annealing the film layer obtained after coating in air with an air humidity of 35-40%, an annealing temperature of 160° C., and a time of 15 min, and obtaining a perovskite light-absorbing layer after cooling.

[0132] Comparative Example 1

[0133] The difference from Example 3 is that the preparation method of the perovskite light absorbing layer in step (3) is different. The preparation method of the perovskite light absorbing layer in this comparative example is:

[0134] (1) Evaporation of inorganic salt: dual-source co-evaporation is adopted, source 1 is PbI2, and the evaporation rate is Source 2 is CsBr, and the evaporation rate is The total thickness of the inorganic material layer is 600nm, and the total evaporation time is 1250s. The relationship curve between the evaporation rate and time of PbI2 and CsBr is shown in Figure 4 shown.

[0135] (2) Preparation of organic ammonium salt solution: a mixed solution of MAX and FAX was prepared, wherein MAX includes MABr and MACl, and FAX includes FAI and FABr. The concentration of FAI in the organic ammonium salt solution is 0.318 M, the concentration of FABr is 0.120 M, the concentration of MABr is 0.212 M, and the concentration of MACl is 0.082 M. The solvent is isopropanol.

[0136] (3) Organic ammonium salt coating: This process is carried out in a glove box by spin coating. The prepared organic ammonium salt solution is spin coated on the inorganic material layer at a spin coating rate of 2000 rpm and a spin coating time of 30 s.

[0137] (4) Annealing the film layer obtained after coating in air with an air humidity of 35-40%, an annealing temperature of 160° C., and a time of 15 min, and obtaining a perovskite light-absorbing layer after cooling.

[0138] Comparative Example 2

[0139] The difference from Example 4 is that the preparation method of the perovskite light absorbing layer in step (3) is different. The preparation method of the perovskite light absorbing layer in this comparative example is:

[0140] (1) Evaporation of inorganic salt: Evaporation is carried out by dual-source co-evaporation, source 1 is PbI2, and the evaporation rate is Source 2 is CsBr, and the evaporation rate is Source 3 is PbCl2, and the evaporation rate of PbCl2 maintains a constant growth rate throughout the coating process until it reaches the set maximum rate value. During the evaporation process, the minimum rate of PbCl2 is The maximum rate is The total thickness of the inorganic material layer is 600nm, and the total evaporation time is 1220s. The relationship curve between the evaporation rate and time of PbI2, CsBr and PbCl2 is shown in Figure 5 shown.

[0141] (2) Preparation of organic ammonium salt solution: a mixed solution of MAX and FAX was prepared, wherein MAX includes MABr and MACl, and FAX includes FAI and FABr. The concentration of FAI in the organic ammonium salt solution is 0.318 M, the concentration of FABr is 0.120 M, the concentration of MABr is 0.212 M, and the concentration of MACl is 0.082 M. The solvent is isopropanol.

[0142] (3) Organic ammonium salt coating: This process is carried out in a glove box by spin coating. The prepared organic ammonium salt solution is spin coated on the inorganic material layer at a spin coating rate of 2000 rpm and a spin coating time of 30 s.

[0143] (4) The film layer obtained after coating is annealed under air conditions: the air humidity is 35-40%, the annealing temperature is 160° C., and the time is 15 minutes. After cooling, the perovskite light-absorbing layer is obtained.

[0144] The photoelectric conversion efficiency of the stacked solar cells of Example 3, Example 4, Comparative Example 1 and Comparative Example 2 was tested. The effective area of ​​the cell is 1 cm 2 The IV curve is as follows Figure 6 The test results of various parameters are shown in Table 1:

[0145] Table 1 Photoelectric test results of Examples 3, 4 and Comparative Examples 1, 2

[0146] Devices PCE(%) <![CDATA[V oc (V)]]> <![CDATA[J sc (mA / cm 2 )]]> FF(%) Example 3 30.16 1.89 19.84 80.41 Comparative Example 1 28.29 1.90 18.98 78.10 Example 4 28.99 1.89 19.22 79.42 Comparative Example 2 24.89 1.85 19.25 69.78 Example 5 30.02 1.90 20.95 75.43 Example 6 29.92 1.90 20.35 77.41

[0147] From the data comparison, we can see that:

[0148] 1. All parameters of the battery in Example 3 are higher than those in Comparative Example 1. This is because in Comparative Example 1, the mixed film prepared by the traditional co-evaporation method is a dual-source co-evaporation of PbI2 and CsBr. When it reacts with the organic ammonium salt solution, only the PbI2 on the upper surface can react completely, and the PbI2 buried on the bottom surface cannot directly contact and reacts incompletely, which causes a large number of defects in the perovskite, which has an adverse effect on the battery performance. The excellent performance of Example 3 shows that the addition of PbCl2 to co-evaporation can effectively eliminate the residual PbI2.

[0149] 2. In Example 4, the evaporation rate of PbCl2 remains constant, and the evaporation rates of PbI2 and CsBr remain the same as in Example 3. sc In addition, the other parameters of the battery in Example 4 are close to those in Example 3. This is because the gradient-evaporated PbCl2 in Example 3 optimizes the energy level alignment between the perovskite and the hole transport layer, and promotes the hole transport layer to extract current.

[0150] 3. In Comparative Example 2, the evaporation rate of PbCl2 maintains a constant growth rate throughout the evaporation process, and the evaporation rates of PbI2 and CsBr remain consistent with that in Example 3. This results in the inorganic precursor layer still being densely arranged at the buried interface, and the organic ammonium salt is difficult to penetrate when reacting with it, resulting in PbI2 residue on the buried bottom surface of the perovskite absorption layer, resulting in poor performance.

[0151] Based on the above data, the inorganic precursor evaporation method described in the embodiments of the present application can effectively eliminate the residual PbI2 at the buried interface of the perovskite, optimize the energy level alignment between the perovskite and the hole transport layer, promote the extraction of current by the hole transport layer, and thus improve the performance of the stacked battery.

[0152] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing an organic-inorganic perovskite light absorbing layer, characterized in that: The following steps are involved: A first evaporation source PbI2, a second evaporation source CsX, and a third evaporation source PbCl2 are co-evaporated on the substrate to form an inorganic material layer, wherein X is a halogen; After the evaporation is completed, an organic ammonium salt solution is coated on the inorganic material layer, and the organic ammonium salt solution reacts with the inorganic material layer to form a perovskite light-absorbing layer.

2. The method for preparing an organic-inorganic perovskite light-absorbing layer according to claim 1: the evaporation rate of the third evaporation source gradually decreases over time, the organic ammonium salt solution contains FAX and / or MAX, wherein X is a halogen; the organic ammonium salt is immersed in the evaporation layer to react with the evaporation layer material.

3. The method for preparing the organic-inorganic perovskite light absorbing layer according to claim 1, characterized in that: The evaporation rates of the first evaporation source and the second evaporation source are consistent, and the ratio of the evaporation rate of the first evaporation source to the evaporation rate of the second evaporation source is 1:0.1-1:0.2; preferably, the evaporation rate of the first evaporation source is The evaporation rate of the second evaporation source is The initial evaporation rate of the third evaporation source is The evaporation rate at the end is During the evaporation process, the evaporation rate decreases at a uniform rate.

4. The method for preparing the organic-inorganic perovskite light absorbing layer according to claim 1, characterized in that: The second evaporation source is CsBr or CsI, and the organic ammonium salt includes FAI and FABr, and the molar ratio of the two is FAI:FABr=(4:1) to (1:4).

5. The method for preparing the organic-inorganic perovskite light absorbing layer according to claim 1, characterized in that: The thickness of the light absorbing layer is 400-600nm. One side of the light absorbing layer is a hole transport layer, and the other side is an electron transport layer. The light absorbing layer is deposited on the hole transport layer, and the deposition rate of the third evaporation source gradually decreases from the hole transport layer side to the electron transport layer side.

6. An organic-inorganic perovskite light-absorbing layer, comprising a substance having an ABX3 perovskite structure, characterized in that: A1 ion and A2 ion are arranged on the A position, wherein the A1 ion is Cs + The A2 ion is an organic amine ion, and the B position is Pb 2+ , the X position is 1 - or Br - or Cl - , where Cl - The content gradually decreases from the side close to the hole transport layer to the side close to the electron transport layer.

7. The organic-inorganic perovskite light absorbing layer according to claim 6, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 5.

8. A method for preparing a solar cell containing a perovskite light absorbing layer, characterized in that: The following steps are involved: Obtaining a substrate; directly or indirectly depositing a hole transport layer on the substrate; directly or indirectly depositing a perovskite light absorbing layer on the hole transport layer; directly or indirectly depositing an electron transport layer on the perovskite light absorbing layer; directly or indirectly depositing an electrode on the electron transport layer; The preparation method of the perovskite light absorbing layer is: A first evaporation source PbI2, a second evaporation source CsX, and a third evaporation source PbCl2 are co-evaporated on the substrate to form an inorganic material layer, wherein X is a halogen; After the evaporation is completed, an organic ammonium salt solution is coated on the inorganic material layer, and the organic ammonium salt solution reacts with the inorganic material layer to form a perovskite light-absorbing layer.

9. The preparation method according to claim 8, characterized in that: The materials of each layer of the perovskite solar cell meet one, two or more of the following requirements: ——The hole transport layer material is a combination of one or more of MeO-2PACz ([2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), Me-4PACz ((4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), 4PADCB ((4-(7h-dibenzo[c,g]carbazole-7-yl)butyl)phosphonic acid), and nickel oxide (NiOx); A passivation layer is provided between the perovskite light absorbing layer and the electron transport layer, and the passivation layer material is ethylenediamine dihydroiodide (EDAI2); ——The materials of the electron transport layer are tin dioxide (SnO2), [6,6]-phenyl C61 butyric acid methyl ester (PC 61 BM), carbon 60 (C 60 ), one or more combinations of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP); A buffer layer is deposited on the electron transport layer, and the buffer layer is a combination of one or more of tin oxide (SnO2), titanium dioxide (TiO2), and zinc oxide (ZnO).

10. A solar cell containing a perovskite light-absorbing layer, comprising a light-absorbing layer, a hole transport layer disposed on one side of the light-absorbing layer, and an electron transport layer disposed on the other side of the light-absorbing layer, wherein the light-absorbing layer contains a substance having an ABX3 perovskite structure, characterized in that: A1 ion and A2 ion are arranged on the A position, wherein the A1 ion is Cs + The A2 ion is a methylamine ion or a formamidine ion, and the B position is Pb 2+ , the X position is 1 - or Br - or Cl - , where Cl - The content gradually decreases from the side close to the hole transport layer to the side close to the electron transport layer.

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