A perovskite solar cell

Abstract

The invention discloses a perovskite solar cell, belonging to the technical field of solar cells. The perovskite solar cell includes a perovskite layer, and an interface modification layer is provided on the surface of the perovskite layer, and the interface modification layer is made of a passivator and a modifier, and the passivator is selected from 2-phenylethylamine hydroiodide, 2-phenylethylamine hydrochloride, benzylamine hydrochloride, benzylamine hydroiodide, butylamine hydrobromide, ethylenediamine hydrochloride, ammonium halide, guanidine halide, tetramethylguanidine fluoroborate or one or more of alkali metal halide, and the modifier is selected from methylammonium thiocyanate, formamidine thiocyanate, methylamine halide, formamidine halide, methylamine acetate, formamidine acetate, formamidine formate, methylamine formate, methylamine cyanate or formamidine cyanate One or more. The present invention can effectively improve the crystallinity of perovskite, passivate surface defects, improve the performance of perovskite solar cells, and improve the stability of devices by using a mixed passivator composed of a passivator and a modifier.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a perovskite solar cell. Background Art

[0002] Perovskite solar cells are the fastest-growing type of third-generation thin-film solar cells, with their single-junction efficiency increasing from 3.8% to 25.5% in just over a decade. Perovskite materials are also considered to be the most promising light-absorbing materials for the next generation of low-cost solar cells.

[0003] In the existing technology, the bottleneck of commercialization of perovskite cells is mainly limited by the stability and efficiency of the cells, which cannot meet the requirements of commercialization. Moreover, the lack of efficiency and poor stability are mainly due to surface and internal defects, and it is difficult for commonly used interface modifiers to penetrate the bulk phase passivation defects. In addition, a single interface modifier cannot achieve the dual effects of optimizing crystallization and passivation.

[0004] In order to make perovskite solar cells achieve higher efficiency, adding a modification layer on both sides of the perovskite active layer is an effective way. At present, the commonly used modification layer is to use a single modifier to improve the performance of perovskite solar cells. However, a single interface modifier only modifies the surface of the perovskite and it is difficult to passivate the defects in the bulk phase. Summary of the invention

[0005] The object of the present invention is to provide a perovskite solar cell containing a mixed interface modifier.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A perovskite solar cell comprises a perovskite layer, an interface modification layer is provided on the surface of the perovskite layer,

[0008] The interface modification layer is made of a passivator and a modifier, wherein the passivator is selected from one or more of 2-phenylethylamine hydroiodide, 2-phenylethylamine hydrochloride, benzylamine hydrochloride, benzylamine hydroiodide, butylamine hydrobromide, ethylenediamine hydrochloride, ammonium halide, guanidine halide, tetramethylguanidine fluoroborate or alkali metal halide, and the modifier is selected from one or more of methylammonium thiocyanate, formamidine thiocyanate, methylamine halide, formamidine halide, methylamine acetate, formamidine acetate, formamidine formate, methylamine formate, methylamine cyanate or formamidine cyanate.

[0009] Furthermore, the weight ratio of the passivator to the modifier is 0.5-5:0.5-5.

[0010] Furthermore, the passivating agent is 2-phenylethylamine hydroiodide, and the modifying agent is methylammonium thiocyanate.

[0011] Furthermore, the weight ratio of the 2-phenylethylamine hydroiodide to methylammonium thiocyanate is 0.5-5:0.5-5, preferably 1-3:1-3.

[0012] Furthermore, the perovskite solar cell is a single-junction cell or a double-junction stacked cell.

[0013] The method for preparing the above-mentioned perovskite solar cell is to add the passivator and the modifier into a solvent to prepare a mixed solution, and then deposit the mixed solution on the surface of the perovskite layer by spin coating, scraping or spraying.

[0014] Furthermore, the solvent is selected from alcohols, aromatic hydrocarbons, esters or ethers.

[0015] At present, the commonly used interface modifiers for perovskites are to passivate various defects on the surface of perovskites to reduce recombination centers, or to form gradient energy levels on the surface to improve carrier transport. The present invention uses a mixed passivator composed of a passivator and a modifier, wherein the passivator is a commonly used molecule for passivating defects, and the modifier can optimize the secondary crystallization of perovskites. Therefore, during the secondary crystallization of the modifier, the passivator is sent into the bulk phase to passivate the bulk defects. In addition, since it is an interface modifier, most of the passivation molecules remain on the surface to passivate defects. Another advantage of the mixed interface modifier is that the proportion of different modifier molecules can be changed in the components of different perovskites to achieve the best results.

[0016] Compared with traditional single interface modifiers, the use of multiple molecular mixtures as interface modifiers has the following advantages: 1) re-optimization of crystallinity; 2) simultaneous passivation of surface and bulk defects; 3) formation of gradient energy level structures, providing new ideas for interface modifiers to improve the performance of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a single-junction perovskite solar cell in the present invention.

[0018] Figure 2 This is the cell efficiency curve of the perovskite solar cell obtained in Example 1. DETAILED DESCRIPTION

[0019] At present, the efficiency of perovskite solar cells is low, and a single interface modifier only modifies the surface of the perovskite, and it is difficult to passivate the defects in the bulk phase. On the one hand, a single interface modifier is difficult to passivate the surface defects while optimizing the quality of the perovskite grains; on the other hand, a single interface modifier is difficult to be compatible with perovskites of various components, and the types of defects on the surfaces of different perovskites are quite different, so it is difficult for a single interface modifier to achieve the desired effect. The present invention mainly improves the strategy of interface modification, and mixes interface modifiers on the surface of the perovskite layer, and utilizes the synergistic effect of different molecules to passivate the perovskite, which can not only effectively improve the crystallinity of the perovskite and passivate the surface defects, but also form a gradient energy level structure at the interface, thereby improving the performance of the perovskite solar cell and improving the stability of the device.

[0020] The modification strategy of the present invention can be applied to single-junction cells or double-junction stacked cells; the interface modification layer deposited on the surface of the perovskite layer can be the backlight side ( Figure 1 (a)), or the light receiving surface ( Figure 1 (as shown in (b)).

[0021] The following takes a single-junction cell and an interface modification layer on the backlight side as an example to further illustrate the technical solution of the present invention:

[0022] like Figure 1 As shown in (a), the perovskite solar cell of the present invention comprises, from the light-receiving front side to the light-receiving back side, a conductive transparent substrate, a first electron (hole) transport layer, a perovskite layer, an interface modification layer, a second hole (electron) transport layer and a back electrode.

[0023] Among them, the conductive transparent substrate can be an indium tin oxide (ITO) substrate, a fluorine-doped tin oxide (FTO) substrate, an indium zinc oxide (IZO) substrate, or the like.

[0024] The hole transport layer uses inorganic transport materials such as nickel oxide (NiO), cuprous oxide (Cu2O), molybdenum oxide (MoO3), copper iodide (CuI), and redox graphene, poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA, poly (triaryl amine)), 2,2',7,7'-tetrakis [N,N-di (4-methoxyphenyl) amino] -9,9'-spirobifluorene (Spiro-OMeTAD), poly 3,4-ethylenedioxythiophene: polystyrene sulfonate (PEDOT:PSS), poly [bis (4-phenyl) (4-butylphenyl) amine] (Ploy-TPD), [2- (9 H -carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9 H -carbazol-9-yl)ethyl]phosphonic acid and one or more organic p-type semiconductor materials.

[0025] The electron transport layer is made of titanium oxide (TiO2), tin oxide (SnO2), zinc oxide (ZnO), fullerene (C 60 ), graphene, fullerene derivatives (PCBM) and other one or more n-type semiconductor materials, the electron transport layer can be prepared by deposition methods including but not limited to electron beam evaporation, thermal evaporation, magnetron sputtering, atomic layer deposition, spin coating, scraping and the like.

[0026] The back electrode is a metal electrode, such as gold, palladium, silver, titanium, chromium, nickel, aluminum, copper, etc.

[0027] The interface modification layer is made of a passivator and a modifier, wherein the passivator is selected from one or more of 2-phenylethylamine hydroiodide, 2-phenylethylamine hydrochloride, benzylamine hydrochloride, benzylamine hydroiodide, butylamine hydrobromide, ethylenediamine hydrochloride, ammonium halide, guanidine halide, tetramethylguanidine fluoroborate or alkali metal halide, and the modifier is selected from one or more of methylammonium thiocyanate, formamidine thiocyanate, methylamine halide, formamidine halide, methylamine acetate, formamidine acetate, formamidine formate, methylamine formate, methylamine cyanate or formamidine cyanate.

[0028] The perovskite layer may be one of a pure lead perovskite layer, a pure tin perovskite layer or a lead-tin mixed perovskite layer.

[0029] In one embodiment of the present invention, the passivator is 2-phenylethylamine hydroiodide, and the modifier is methylammonium thiocyanate. The ratio of the passivator to the modifier is 1-3:1-3, preferably 2:1. The perovskite layer is a pure tin blended perovskite layer, which is FA 0.8 Cs 0.15 MA 0.05 Pb(I 0.82 Br 0.18 ), wherein FA is formamidinium ion and MA is methylamine ion.

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and specific examples, but it should not be construed as limiting the present invention. Without departing from the spirit and substance of the present invention, the modification or replacement of the method, steps or conditions of the present invention all belong to the scope of the present invention. The experimental methods and reagents without specifying the specific conditions in the examples are all in accordance with the conventional conditions in the art.

[0031] Example 1

[0032] The structure of the perovskite solar cell of this embodiment is as follows Figure 1 As shown, the preparation process is as follows:

[0033] 1. Deposit a layer of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid as a hole transport layer on a cleaned ITO substrate;

[0034] 2. Deposit a layer of FA on the hole transport layer 0.8 Cs 0.15 MA 0.05 Pb(I 0.82 Br 0.18 ) perovskite, thickness 500nm;

[0035] 3. Deposit a mixed interface modification layer on the perovskite layer, dissolve phenylethylamine iodide (PEAI) and methylamine thiocyanate (MASCN) in isopropanol as an interface modifier and deposit it on the perovskite layer, and anneal on a hot plate at 100°C for 5 minutes;

[0036] Meanwhile, the blank was used without deposition of interface modification layer, and the control was used by deposition of single interface modification agent phenylethylamine iodide (PEAI);

[0037] 4. Use thermal evaporation to deposit a layer of fullerene (C60) as an electron transport layer with a thickness of about 25 nm;

[0038] 5. Use atomic layer deposition of tin dioxide (SnO2) as a sputtering protection layer with a thickness of about 20nm;

[0039] 6. Use a sputtering device to sputter a layer of ITO as a transparent conductive layer with a thickness of 80nm;

[0040] 7. Use thermal evaporation to deposit a layer of metallic copper as an electrode.

[0041] The device prepared above was subjected to performance testing, and the results are as follows:

[0042]

[0043] As can be seen from the table above, the introduction of mixed interface modifiers into perovskite solar cells can effectively improve the cell efficiency of the device; Figure 2 As shown, when the weight ratio of PEAI and MASCN is 2:1, an efficiency of 20.28% is achieved on a single junction cell, the efficiency of the cell introducing a single interface modifier is 18.14%, and the efficiency without interface modifier treatment is 17.14%.

Claims

1. A perovskite solar cell, comprising a perovskite layer, characterized in that: There is an interface modification layer on the surface of the perovskite layer, and the interface modification layer is made of a passivator and a modifier. The passivator and the modifier are added to a solvent to form a mixed solution, and then the mixed solution is deposited on the surface of the perovskite layer by spin coating, scraping or spraying. The passivator is 2-phenylethylamine hydroiodide, and the modifier is methylammonium thiocyanate.

2. The perovskite solar cell according to claim 1, characterized in that: The weight ratio of the passivator to the modifier is 0.5-5:0.5-5.

3. The perovskite solar cell according to claim 1, characterized in that: The perovskite solar cell is a single-junction cell or a double-junction stacked cell.

4. A method for preparing a perovskite solar cell according to claim 1, characterized in that: The passivating agent and the modifier are added to a solvent to prepare a mixed solution, which is then deposited on the surface of the perovskite layer by spin coating, scraping or spraying.

5. The preparation method according to claim 4, characterized in that: The solvent is selected from alcohols, aromatic hydrocarbons, esters or ethers.

Images