Two-step perovskite precursor solution, metal halide perovskite thin film, perovskite solar cell and preparation method thereof

Abstract

The invention discloses a two-step method perovskite precursor solution, a metal halide perovskite thin film, a perovskite solar cell and a preparation method of the two-step method perovskite precursor solution. A mercaptothiazole-doped metal halide precursor solution preparation step: dissolving a metal halide material into a first solvent to prepare a metal halide precursor solution, adding a mercaptothiazole material into the metal halide precursor solution, and heating and stirring to obtain the mercaptothiazole-doped metal halide precursor solution; and S102, a cation halide precursor solution preparation step: dissolving a cation halide material into a second solvent to prepare the cation halide precursor solution. According to the invention, the unreacted metal halide phase in the perovskite thin film can be effectively reduced, and meanwhile, the damage of moisture to the perovskite thin film is inhibited, so that the efficiency and other performances of the perovskite solar cell are improved.

Description

Technical Field

[0001] The invention relates to the field of optoelectronic technology, and in particular to a two-step perovskite precursor solution, a metal halide perovskite film, a perovskite solar cell and a preparation method thereof. Background Art

[0002] Metal halide perovskite solar cells are considered to be the most commercially promising new generation battery technology.

[0003] At present, the preparation of metal halide perovskite film by two-step deposition process is one of the main preparation methods of perovskite film. However, the efficiency of perovskite solar cells produced by metal halide perovskite prepared by this method still lags behind that of crystalline silicon cells. The reason is that when the metal halide perovskite film is deposited by the two-step method, the crystallization rate of the reaction between the metal halide layer and the cationic halide solution is too fast, resulting in the cationic halide solution not completely penetrating into the metal halide layer to form a relatively dense perovskite structure, which hinders the continuous penetration of the cationic halide solution, causing incomplete reaction between the metal halide and the cationic halide, resulting in a large amount of unreacted metal halide phase in the metal halide perovskite film, and aggravating the formation of uncoordinated lead ions in the perovskite film, which seriously limits the performance of the device and causes a loss in the efficiency of the perovskite solar cell prepared by the two-step method. At the same time, when the metal halide perovskite film encounters moisture erosion, it will quickly decompose into a non-perovskite phase, causing serious performance degradation. Although encapsulation can greatly curb the erosion of moisture on the perovskite film, some moisture will still penetrate the encapsulation material into the perovskite film layer, causing the perovskite film layer to decompose, which will also cause a loss in the efficiency of the perovskite solar cell. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a two-step perovskite precursor solution, a metal halide perovskite film, a perovskite solar cell and a preparation method thereof in view of the above-mentioned deficiencies in the prior art, which can effectively reduce the unreacted metal halide phase in the perovskite film and inhibit the damage of moisture to the perovskite film, thereby improving the efficiency and other performance of the perovskite solar cell.

[0005] The technical solution of the present invention to solve the above technical problems is:

[0006] According to a first aspect of the present invention, there is provided a two-step method for preparing a perovskite precursor solution, comprising:

[0007] S101, a step of preparing a metal halide precursor solution doped with mercaptothiazole: dissolving a metal halide material in a first solvent to prepare a metal halide precursor solution,

[0008] Adding mercaptothiazole material to a metal halide precursor solution, heating and stirring the solution, and obtaining a metal halide precursor solution doped with mercaptothiazole;

[0009] S102, cationic halide precursor solution preparation step: dissolving the cationic halide material into a second solvent to obtain a cationic halide precursor solution.

[0010] Optionally, the mercaptothiazole material includes any one or more of 2-mercaptothiazole, 2,5-dimercaptothiazole, 2-mercapto-1,3,4-thiadiazole, and 2,5-dimercapto-1,3,4-thiadiazole.

[0011] Optionally, the metal halide material has a molecular formula including BX2, where B is Pb 2+ Sn 2+ One or two of X include halogen ions I - Br - , Cl - Any one or more of the .

[0012] Optionally, the first solvent includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

[0013] Optionally, the concentration of the metal halide material in the first solvent is in the range of 1.0 to 2.0 M.

[0014] Optionally, in step S101, the heating temperature is 30-60°C.

[0015] Optionally, the cationic halide material has a molecular formula of AX, where A is CH3NH3 + 、CH(NH2)2 + 、(CH3)2NH2 + , Cs + Any one or more of the following, X is a halogen ion I - Br - , Cl - Any one or more of the .

[0016] Optionally, the second solvent includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

[0017] Optionally, the concentration of the cationic halide material in the second solvent is in the range of 1.0 to 2.0 M.

[0018] According to a second aspect of the present invention, a two-step perovskite precursor solution is provided, comprising a metal halide precursor solution doped with mercaptothiazole and a cationic halide precursor solution prepared by the above-mentioned preparation method of the two-step perovskite precursor solution.

[0019] According to a third aspect of the present invention, there is provided a method for preparing a metal halide perovskite thin film, comprising:

[0020] S201, coating the metal halide precursor solution doped with mercaptothiazole prepared by the method described above on the substrate, and annealing to obtain a metal halide layer;

[0021] S202, coating the cationic halide precursor solution prepared by the method described above on the metal halide layer, and annealing to obtain a metal halide perovskite film.

[0022] Optionally, the method further comprises:

[0023] S203, preparing a mercaptothiazole material solution, depositing it on the surface of the metal halide perovskite film, and annealing to form an interface protection layer on the surface of the metal halide perovskite film.

[0024] Optionally, in step S201, the annealing temperature is 50-100°C, and the annealing time is 0.1-5 min.

[0025] Optionally, in step S202, the annealing temperature is 90-250°C, and the annealing time is 5-20 minutes.

[0026] Optionally, in step S203, the solvent used to prepare the mercaptothiazole material solution includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

[0027] Optionally, in step S203, the solvent in the mercaptothiazole material solution is chlorobenzene, and the concentration thereof is 0.1-10 mg / mL.

[0028] Optionally, in step S203, the annealing temperature is 60-120°C, and the annealing time is 1-10 minutes.

[0029] According to a fourth aspect of the present invention, there is provided a metal halide perovskite thin film, which is prepared by the above-mentioned method for preparing the metal halide perovskite thin film.

[0030] According to a fifth aspect of the present invention, a perovskite solar cell is provided, which comprises, from bottom to top, a conductive substrate, a first carrier transport layer, the metal halide perovskite film mentioned above, a second carrier transport layer, a buffer layer and an electrode layer.

[0031] Optionally, the metal halide perovskite film includes a perovskite light absorbing layer and an interface passivation protective layer, and the interface passivation protective layer is deposited on the surface of the perovskite light absorbing layer.

[0032] Optionally, the thickness of the perovskite light absorbing layer is 200-1000 nm.

[0033] Optionally, the thickness of the interface passivation protection layer is 2 to 40 nm.

[0034] Optionally, the conductive substrate includes any one of ITO, FTO, and AZO.

[0035] Optionally, the first carrier transport layer is a hole transport layer, and the second carrier transport layer is an electron transport layer; or, the first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer;

[0036] The material of the hole transport layer is [2-(9H-carbazole-9-yl)ethyl]phosphate (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphate (MeO-2PACz), [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphate (Me-2PACz), [4-(9H-carbazole-9-yl)butyl]phosphate (4PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphate (MeO-4PACz), [ 4-(7H-dibenzocarbazole-7-yl)butyl]phosphoric acid (4PADCB), 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 2,2',7,7'-tetrakis[N,N-di(4-methylphenyl)amino]-9,9'-spirobifluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3-hexylthiophene-2,5-diyl) (P3HT), poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD), nickel oxide (NiO x ), cuprous thiocyanate (CuSCN), copper iodide (CuI);

[0037] The material of the electron transport layer includes C 60, any one of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), tin oxide (SnO2), zinc oxide (ZnO), and titanium oxide (TiO2).

[0038] Optionally, the thickness of the first carrier transport layer is 1 to 100 nm, and the thickness of the second carrier transport layer is 1 to 100 nm.

[0039] Optionally, the buffer layer is made of SnO2 or 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP).

[0040] Optionally, the buffer layer has a thickness of 1 to 10 nm.

[0041] Optionally, the electrode layer is a metal electrode layer, the material of the electrode layer includes any one of gold, silver and copper, and the thickness of the electrode layer is 70 to 150 nm.

[0042] According to a sixth aspect of the present invention, there is provided a method for preparing a perovskite solar cell, comprising:

[0043] depositing a first carrier transport layer on a conductive substrate;

[0044] Taking the first carrier transport layer as a substrate, a metal halide perovskite film is deposited on the first carrier transport layer using the preparation method of the metal halide perovskite film;

[0045] A second carrier transport layer, a buffer layer, and an electrode layer are sequentially deposited on the metal halide perovskite film to obtain a perovskite solar cell.

[0046] Optionally, a deposition method of the first carrier transport layer and the second carrier transport layer includes any one of coating, thermal evaporation, and magnetron sputtering.

[0047] Optionally, the coating includes any one of spin coating, spray coating, blade coating, and slit coating.

[0048] Optionally, the electrode layer is deposited by thermal evaporation at a deposition rate of

[0049] Compared with the prior art, the two-step perovskite precursor solution, metal halide perovskite film and preparation method thereof, perovskite solar cell and preparation method thereof of the present invention have the following beneficial effects:

[0050] (1) It can slow down the reaction rate of cationic halide and metal halide layer when preparing metal halide perovskite film by two-step deposition process, so that cationic halide can fully penetrate into the metal halide layer, so that the two can fully react, reduce the content of unreacted lead iodide in the perovskite film, improve the crystal quality of perovskite material, and enhance the crystallinity of perovskite material.

[0051] (2) It can passivate the uncoordinated lead defects in the bulk and interface of metal halide perovskite films.

[0052] (3) A hydrophilic protective layer (i.e., an interface passivation protective layer) can be formed on the surface of the metal halide perovskite film to capture moisture that penetrates into the perovskite solar cell and prevent moisture from corroding the metal halide perovskite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of a two-step method for preparing a perovskite precursor solution in an embodiment of the present invention;

[0054] Figure 2 Schematic diagram of a method for preparing a metal halide perovskite film in an embodiment of the present invention;

[0055] Figure 3 is a schematic structural diagram of a perovskite solar cell in an embodiment of the present invention;

[0056] Figure 4 is the X-ray diffraction pattern of the metal halide perovskite film in Example 2 of the present invention;

[0057] Figure 5 is an X-ray diffraction pattern of the metal halide perovskite film in the comparative example of the present invention;

[0058] Figure 6 is an electron microscope photograph of the metal halide perovskite film in Example 2 of the present invention;

[0059] Figure 7 An electron microscope photograph of a metal halide perovskite film in a comparative example of the present invention;

[0060] Figure 8 This is a stability comparison chart of the perovskite solar cells in Example 2 of the present invention and the comparative example.

[0061] In the figure: 1. Conductive substrate; 2. First carrier transport layer; 3. Perovskite light absorption layer; 4. Passivation protection layer; 5. Second carrier transport layer; 6. Buffer layer; 7. Electrode layer; 8. Metal halide perovskite film. DETAILED DESCRIPTION

[0062] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0063] In view of the fact that in the deposition process of the metal halide perovskite film prepared by the two-step method in the prior art, the metal halide layer reacts rapidly with the cationic halide, resulting in the cationic halide solution not completely penetrating into the metal halide layer, and a relatively dense metal halide perovskite structure is formed on the surface of the metal halide layer, thereby hindering the continued penetration of the cationic solution, resulting in insufficient reaction between the metal halide material and the organic cationic halide, forming a large amount of unreacted lead iodide, reducing the metal halide perovskite phase in the perovskite film, and aggravating the formation of uncoordinated lead ions in the perovskite film, which will cause a loss in the efficiency of the perovskite solar cell. The present invention provides a two-step method for preparing a perovskite precursor solution, comprising:

[0064] S101, a step of preparing a metal halide precursor solution doped with mercaptothiazole: dissolving a metal halide material in a first solvent to obtain a metal halide precursor solution, adding a mercaptothiazole material to the metal halide precursor solution, and heating and stirring the solution to obtain a metal halide precursor solution doped with mercaptothiazole;

[0065] S102, cationic halide precursor solution preparation step: dissolving the cationic halide material into a second solvent to obtain a cationic halide precursor solution.

[0066] Correspondingly, the present invention also provides a two-step perovskite precursor solution, which includes a metal halide precursor solution doped with mercaptothiazole and a cationic halide precursor solution prepared by the method described above.

[0067] Furthermore, the present invention provides a method for preparing a metal halide perovskite thin film, comprising:

[0068] S201, coating the metal halide precursor solution doped with mercaptothiazole prepared by the method described above on the substrate, and annealing to obtain a metal halide layer;

[0069] S202, coating the cationic halide precursor solution prepared by the method described above on the metal halide layer, and annealing to obtain a metal halide perovskite film.

[0070] Correspondingly, the present invention also provides a metal halide perovskite thin film, which is prepared by the above-mentioned method for preparing the metal halide perovskite thin film.

[0071] Furthermore, the present invention also provides a perovskite solar cell, which comprises, from bottom to top, a conductive substrate, a first carrier transport layer, the metal halide perovskite film mentioned above, a second carrier transport layer, a buffer layer and an electrode layer.

[0072] Accordingly, the present invention also provides a method for preparing a perovskite solar cell, comprising:

[0073] depositing a first carrier transport layer on a conductive substrate;

[0074] Taking the first carrier transport layer as a substrate, a metal halide perovskite film is deposited on the first carrier transport layer using the above-mentioned method for preparing the metal halide perovskite film;

[0075] A second carrier transport layer, a buffer layer, and an electrode layer are sequentially deposited on the metal halide perovskite film to obtain a perovskite solar cell.

[0076] Example 1

[0077] like Figure 1 As shown, this embodiment discloses a two-step method for preparing a perovskite precursor solution, comprising:

[0078] S101, a step of preparing a metal halide precursor solution doped with mercaptothiazole: dissolving a metal halide material in a first solvent to obtain a metal halide precursor solution, adding a mercaptothiazole material to the metal halide precursor solution, and heating and stirring the solution to obtain a metal halide precursor solution doped with mercaptothiazole;

[0079] S102, cationic halide precursor solution preparation step: dissolving the cationic halide material into a second solvent to obtain a cationic halide precursor solution.

[0080] Specifically, the mercaptothiazole material includes any one or more of 2-mercaptothiazole, 2,5-dimercaptothiazole, 2-mercapto-1,3,4-thiadiazole, and 2,5-dimercapto-1,3,4-thiadiazole.

[0081] In this embodiment, the mercaptothiazole material is preferably 2,5-dimercapto-1,3,4-thiadiazole, and its concentration is 0.1-2.0 mg / mL.

[0082] The two-step method for preparing the perovskite precursor solution of this embodiment introduces a mercaptothiazole material into the metal halide precursor solution. The mercaptothiazole material can coordinate with the metal halide to form a complex. The formation of the complex can slow down the reaction rate between the cationic halide precursor solution and the metal halide during the two-step method for preparing the metal halide perovskite film, thereby giving the cationic halide precursor solution more time to penetrate into the metal halide layer, increasing the metal halide and the cationic halide precursor solution. The reaction time between the two contacts makes the two-step perovskite crystallization process more complete, reduces the unreacted lead iodide content in the metal halide layer perovskite film, and improves the crystallization quality of the metal halide layer perovskite film; at the same time, after the deposition and crystallization are completed, due to the large molecular size of mercaptothiazole, it cannot enter the crystal lattice of the metal halide perovskite and will exist at the grain boundary. At this time, the mercaptothiazole material can coordinate with the uncoordinated lead ions in the metal halide perovskite film, thereby passivating the non-radiative recombination centers caused by the uncoordinated lead ions.

[0083] By sequentially depositing the metal halide precursor solution and the cationic halide precursor solution prepared by the method, a metal halide perovskite film can be prepared. The molecular formula of the metal halide perovskite film is ABX3. As a perovskite light-absorbing layer of a perovskite solar cell, the efficiency and other performance of the perovskite solar cell can be improved.

[0084] In some embodiments, the metal halide material has a molecular formula comprising BX2, where B is Pb 2+ Sn 2+ One or two of X include halogen ions I - Br - , Cl - Any one or more of the .

[0085] In some embodiments, the first solvent includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

[0086] In this embodiment, the first solvent is a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0087] In some embodiments, the concentration of the metal halide material in the first solvent is in the range of 1.0 to 2.0 M, at which point the thickness of the prepared metal halide layer is most suitable.

[0088] In some embodiments, in step S101, the heating temperature is 30-60°C, and should be lower than the boiling point of the solvent, so that the solute can be dissolved in the solvent more quickly and fully, and the time is shorter than stirring at room temperature. In this embodiment, the heating temperature is preferably 50°C, and the stirring time is 2 hours.

[0089] In some embodiments, the cationic halide material has a molecular formula of AX, A is CH3NH3 + (methylamine ion, MA + )、CH(NH2)2 + (dimethylammonium ion, DMA + )、(CH3)2NH2 + (Formamidinium ion, FA + ), Cs + Any one or more of, X includes halogen ion I - Br - , Cl - Any one or more of the .

[0090] In some embodiments, the second solvent includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

[0091] In this embodiment, the second solvent is isopropyl alcohol (IPA) solution.

[0092] In some embodiments, the concentration of the cationic halide material in the second solvent is in the range of 1.0 to 2.0 M to ensure complete reaction with the metal halide when preparing the metal halide perovskite film.

[0093] Furthermore, the present embodiment also discloses a two-step perovskite precursor solution, which includes a metal halide precursor solution doped with mercaptothiazole and a cationic halide precursor solution prepared by the above-mentioned preparation method of the two-step perovskite precursor solution.

[0094] Furthermore, if Figure 2 As shown, this embodiment also discloses a method for preparing a metal halide perovskite film, comprising:

[0095] S201, coating the metal halide precursor solution doped with mercaptothiazole prepared by the method described above on the substrate, and annealing to obtain a metal halide layer.

[0096] S202, coating the cationic halide precursor solution prepared by the method described above on the metal halide layer, allowing the cationic halide solution to penetrate into the metal halide layer through an infiltration process, and partially forming perovskite crystal nuclei after mutual reaction between the two, and annealing, so that the perovskite material undergoes a phase transition and grows completely, to obtain a metal halide perovskite film with excellent photoelectric properties.

[0097] In the method for preparing the metal halide perovskite film of the present embodiment, the metal halide precursor solution doped with mercaptothiazole as described above is used, and the mercaptothiazole material can coordinate with the metal halide to form a complex. The formation of the complex can slow down the reaction rate between the cationic halide precursor solution and the metal halide in the process of preparing the metal halide perovskite film by the two-step method, thereby giving the cationic halide precursor solution more time to penetrate into the metal halide layer, increasing the reaction rate between the metal halide and the cationic halide precursor solution. The contact and reaction time between the two make the two-step perovskite crystallization process more complete, reduce the unreacted lead iodide content in the metal halide layer perovskite film, and improve the crystallization quality of the metal halide layer perovskite film; at the same time, after the deposition and crystallization are completed, due to the large molecular size of mercaptothiazole, it cannot enter the crystal lattice of metal halide perovskite and will exist at the grain boundary. At this time, the mercaptothiazole material can coordinate with the uncoordinated lead ions in the metal halide perovskite film, thereby passivating the non-radiative recombination centers caused by the uncoordinated lead ions.

[0098] In some embodiments, Figure 2 As shown, the method also includes:

[0099] S203, mixing the mercaptothiazole material with a third solvent to prepare a mercaptothiazole material solution, and depositing the mercaptothiazole material solution on the surface of the metal halide perovskite film, and annealing to form an interface protection layer on the surface of the metal halide perovskite film.

[0100] The preparation method of the metal halide perovskite film of this embodiment can further achieve the following effects by further introducing a mercaptothiazole material on the surface of the metal halide perovskite film: 1) the mercapto groups and thiazoles in the mercaptothiazole material can coordinate with the uncoordinated lead ion defects at the grain boundaries and surfaces of the metal halide perovskite film, thereby further passivating the defects at the corresponding sites and reducing non-radiative recombination; 2) the sulfur atoms in the mercapto groups in the mercaptothiazole material can form hydrogen bonds with hydrogen atoms in water, thereby capturing a small amount of moisture that penetrates into the interior of the perovskite solar cell device, preventing this portion of moisture from continuing to corrode the metal halide perovskite film.

[0101] The method prepares a metal halide perovskite film by sequentially depositing a metal halide precursor solution and a cationic halide precursor solution, wherein the metal halide perovskite film has a molecular formula of ABX3 and serves as a perovskite light-absorbing layer of a perovskite solar cell to improve the efficiency and other performance of the perovskite solar cell.

[0102] In some embodiments, in step S201 , the annealing temperature is 50-100° C. and the annealing time is 0.1-5 min, so as to evaporate the organic solvent in the metal halide layer.

[0103] In some embodiments, in step S202, the annealing temperature is 90-250°C, and the annealing time is 5-20 minutes. In actual operation, different annealing temperatures can be selected according to different perovskite ABX3 material systems.

[0104] In some embodiments, in step S203, the solute in the mercaptothiazole material solution (i.e., mercaptothiazole material) includes any one or more of 2-mercaptothiazole, 2,5-dimercaptothiazole, 2-mercapto-1,3,4-thiadiazole, and 2,5-dimercapto-1,3,4-thiadiazole.

[0105] In some embodiments, in step S203, the solvent in the mercaptothiazole material solution (i.e., the third solvent) includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

[0106] In this embodiment, the third solvent is preferably chlorobenzene, and the concentration of the mercaptothiazole material is 0.1-10 mg / mL, preferably 1 mg / mL, to prevent too low a concentration from making the material effect insignificant and too high a concentration from destroying the formation of the perovskite crystal structure.

[0107] In some embodiments, in step S203, the annealing temperature is 60-120°C, and the annealing time is 1-10 minutes.

[0108] Furthermore, this embodiment also discloses a metal halide perovskite thin film, which is prepared by the above-mentioned method for preparing the metal halide perovskite thin film.

[0109] Specifically, the metal halide perovskite film at least includes a metal halide perovskite film with excellent photoelectric properties that does not include an interface passivation protective layer and is deposited on the substrate according to the above steps S201 and S202. In some embodiments, it also includes an interface passivation protective layer deposited on the above-mentioned metal halide perovskite film with excellent photoelectric properties that does not include an interface passivation protective layer according to step S203.

[0110] Furthermore, if Figure 3 As shown, this embodiment also discloses a perovskite solar cell, which includes, from bottom to top, a conductive substrate, a first carrier transport layer, the metal halide perovskite film mentioned above, a second carrier transport layer, a buffer layer and an electrode layer.

[0111] In some embodiments, the metal halide perovskite film includes a perovskite light absorbing layer and an interface passivation protective layer, the perovskite light absorbing layer is deposited on the first carrier transport layer, and the interface passivation protective layer is deposited on the surface of the perovskite light absorbing layer.

[0112] In some embodiments, the thickness of the perovskite light absorbing layer is 200-1000 nm.

[0113] In some embodiments, the thickness of the interface protection layer is 2 to 40 nm.

[0114] In some embodiments, the conductive substrate includes any one of ITO, FTO, and AZO.

[0115] In some embodiments, the first carrier transport layer is a hole transport layer, and the second carrier transport layer is an electron transport layer; or, the first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer.

[0116] Specifically, the material of the hole transport layer is [2-(9H-carbazole-9-yl)ethyl]phosphate (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphate (MeO-2PACz), [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphate (Me-2PACz), [4-(9H-carbazole-9-yl)butyl]phosphate (4PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphate (MeO-4PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate (Me-4PACz), ), [4-(7H-dibenzocarbazole-7-yl)butyl]phosphoric acid (4PADCB), 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 2,2',7,7'-tetrakis[N,N-di(4-methylphenyl)amino]-9,9'-spirobifluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3-hexylthiophene-2,5-diyl) (P3HT), poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD), nickel oxide (NiO x ), cuprous thiocyanate (CuSCN), copper iodide (CuI);

[0117] Specifically, the material of the electron transport layer includes C 60 , any one of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), tin oxide (SnO2), zinc oxide (ZnO), and titanium oxide (TiO2).

[0118] In some embodiments, the thickness of the first carrier transport layer is 1 to 100 nm, and the thickness of the second carrier transport layer is 1 to 100 nm.

[0119] In some embodiments, the buffer layer is made of SnO 2 or 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP).

[0120] In some embodiments, the buffer layer has a thickness of 1 to 10 nm.

[0121] In some embodiments, the electrode layer is a metal electrode layer, the material of the electrode layer includes any one of gold, silver, and copper, and the thickness of the electrode layer is 70 to 150 nm.

[0122] Furthermore, this embodiment also discloses a method for preparing a perovskite solar cell, comprising:

[0123] depositing a first carrier transport layer on a conductive substrate;

[0124] Taking the first carrier transport layer as a substrate, a metal halide perovskite film is deposited on the first carrier transport layer using the above-mentioned method for preparing the metal halide perovskite film;

[0125] A second carrier transport layer, a buffer layer, and an electrode layer are sequentially deposited on the metal halide perovskite film to obtain a perovskite solar cell.

[0126] Specifically, the metal halide perovskite film includes a perovskite light absorption layer and an interface passivation protective layer. First, according to the above steps S201 and S202, a metal halide perovskite film excluding an interface passivation protective layer is deposited on the first carrier transport layer to serve as the perovskite light absorption layer; then, according to step S203, the interface passivation protective layer is deposited on the perovskite light absorption layer;

[0127] In some embodiments, a deposition method of the first carrier transport layer and the second carrier transport layer includes any one of coating, thermal evaporation, and magnetron sputtering.

[0128] In some embodiments, the coating comprises any one of spin coating, spray coating, blade coating, and slit coating.

[0129] In some embodiments, the electrode layer is deposited by thermal evaporation at a deposition rate of

[0130] Compared with the prior art, the two-step perovskite precursor solution, metal halide perovskite film, perovskite solar cell and preparation method thereof of this embodiment have the following advantages:

[0131] (1) It can slow down the reaction rate of cationic halide and metal halide layer when preparing metal halide perovskite film by two-step deposition process, so that cationic halide can fully penetrate into the metal halide layer, so that the two can fully react, reduce the content of unreacted lead iodide in the perovskite film, improve the crystal quality of perovskite material, and enhance the crystallinity of perovskite material.

[0132] (2) It can passivate the uncoordinated lead defects in the bulk and interface of metal halide perovskite films.

[0133] (3) A hydrophilic protective layer (i.e., an interface passivation protective layer) can be formed on the surface of the metal halide perovskite film to capture moisture that penetrates into the perovskite solar cell and prevent moisture from corroding the metal halide perovskite film.

[0134] Example 2

[0135] This embodiment discloses a perovskite solar cell and a preparation method thereof. The preparation method of the cell adopts the preparation method of the metal halide perovskite film described in Example 1 to deposit a metal halide perovskite film on the first carrier transport layer as a perovskite light absorbing layer. Specifically, the steps are as follows:

[0136] S1, conductive substrate treatment: ITO conductive glass was used as the conductive substrate, and glass cleaning agent, deionized water, ethanol, acetone, isopropanol and ethanol were ultrasonicated for 10 min in sequence, and then the substrate was blown dry with dry air, followed by UV-ozone treatment for 15 min;

[0137] S2, preparing a first carrier transport layer solution: dissolving [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphoric acid in anhydrous ethanol, and the concentration of the prepared first carrier transport layer solution is 0.4 mg / mL;

[0138] S3, depositing a first carrier transport layer: depositing the first carrier transport layer by spin coating, spin coating the first carrier transport layer solution in step S2 on the ITO conductive glass obtained in step S1, the spin coating speed is 4000 rpm, the spin coating time is 30 s, and annealing is performed at 100° C. for 10 min to obtain the first carrier transport layer, at which point the first carrier transport layer is a hole transport layer;

[0139] S4, preparing a metal halide precursor solution: dissolving 553.2 mg of PbI2 (lead iodide) in 1 mL of a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a metal halide precursor solution, wherein the volume ratio of DMF to DMSO is 4:1, and heating and stirring at 50° C. for 2 h for later use;

[0140] S5, adding mercaptothiazole material to the metal halide precursor solution: adding 2,5-dimercapto-1,3,4-thiadiazole to the metal halide precursor solution prepared in step S4, the addition amount is 1 mg / mL, to obtain a metal halide precursor solution doped with 2,5-dimercapto-1,3,4-thiadiazole, heating and stirring at 50° C. for 2 h and then setting aside;

[0141] S6, preparing a cationic halide precursor solution: dissolving 154.7 mg of iodoformamidine (FAI), 46.8 mg of cesium iodide (CsI), 19.1 mg of iodomethylamine (MAI), and 15.5 mg of chloromethylamine (MACl) in 1 mL of isopropanol (IPA) solution, stirring for 2 h, and setting aside to obtain a cationic halide precursor solution;

[0142] S7, depositing a metal halide layer: spin coating the metal halide precursor solution doped with 2,5-dimercapto-1,3,4-thiadiazole prepared in steps S4 and S5 on the first carrier transport layer (i.e., substrate) obtained in S3, at a spin coating rate of 3000 rpm for 30 seconds, and annealing at 70° C. for 2 minutes after spin coating to obtain a metal halide layer;

[0143] S8, depositing a cationic halide precursor solution: spin coating the cationic halide precursor solution prepared in step S6 on the metal halide layer obtained in step S7, at a spin coating rate of 3000 rpm for 30 seconds, and annealing at 100° C. for 10 minutes after spin coating to obtain a metal halide perovskite film;

[0144] S9, preparing an interface protection passivation layer: mixing 2,5-dimercapto-1,3,4-thiadiazole and chlorobenzene to obtain a solution with a concentration of 1 mg / mL, and then spin coating the solution on the perovskite light absorbing layer prepared in step (8) at a speed of 5000 rpm for 30 seconds, followed by annealing at 100° C. for 5 minutes to obtain the interface passivation protection layer;

[0145] S10, preparing the second carrier transport layer: using a vacuum thermal evaporation deposition method, C 60 Evaporation is performed on the interface passivation protective layer prepared in step S9 at an evaporation rate of The thickness of C is 30nm. 60Layer, i.e., the second carrier transport layer, in which case the second carrier transport layer is an electron transport layer;

[0146] S11, preparing a buffer layer: using a vacuum thermal evaporation deposition method, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) is deposited on the C prepared in step S10. 60 The evaporation rate is A BCP layer with a thickness of 7 nm, i.e., a buffer layer, is obtained;

[0147] S12, preparing the electrode layer: using a vacuum thermal evaporation deposition method, depositing metallic silver on the BCP layer prepared in step S11, the evaporation rate is A silver layer with a thickness of 125 nm, i.e., the electrode layer, is obtained;

[0148] In summary, a perovskite solar cell is prepared.

[0149] Example 3

[0150] The difference between Example 3 and Example 2 is that step S9 is not performed, and the remaining preparation method steps and parameters are consistent with Example 2.

[0151] Example 4

[0152] The difference between Example 4 and Example 2 is that step S5 is not performed, and the remaining preparation method steps and parameters are consistent with Example 2.

[0153] Example 5

[0154] The difference between Example 5 and Example 2 is that 2-mercapto-1,3,4-thiadiazole is used in step S5 and step S9, and the remaining preparation method steps and parameters are consistent with Example 2.

[0155] Example 6

[0156] The difference between Example 6 and Example 2 is that 2,5-dimercaptothiazole is used in step S5 and step S9, and the remaining preparation method steps and parameters are consistent with Example 2.

[0157] Example 7

[0158] The difference between Example 7 and Example 2 is that 2-mercaptothiazole is used in step S5 and step S9, and the remaining preparation method steps and parameters are consistent with Example 2.

[0159] Example 8

[0160] The difference between Example 8 and Example 2 is that step S5 and step S9 use a mixture of 2-mercaptothiazole and 2-mercapto-1,3,4-thiadiazole in a mass ratio of 1:1, and the remaining preparation method steps and parameters are consistent with Example 2.

[0161] Example 9

[0162] The difference between Example 9 and Example 2 is that the solvent used in step S6 is a mixed solution of isopropyl alcohol (IPA) and N,N-dimethylformamide (DMF) in a volume ratio of 200:1, and the remaining preparation method steps and parameters are consistent with Example 2.

[0163] Comparative Example

[0164] The difference between the comparative example and Example 2 is that step S5 and step S9 are not performed, and the remaining preparation method steps and parameters are consistent with Example 2.

[0165] Performance Testing

[0166] The batteries prepared in Examples 2 to 7 and the comparative example were subjected to current-voltage characteristic (JV) tests, using AM1.5G light source, 100 mW cm -2 The sunlight simulates the light source and obtains the open circuit voltage of the battery (V OC ), short-circuit current density (J SC ), fill factor (FF) and power conversion efficiency (PCE), among which the open circuit voltage (V OC ), short-circuit current density (J SC ), fill factor (FF) is obtained from the tested JV characteristic curve, power conversion efficiency (PCE) = (V OC ×J SC ×FF) / 100mW cm -2 , the test results are shown in Table 1.

[0167] Table 1 Battery performance table

[0168] Voc(V) <![CDATA[Jsc(mA / cm 2 )]]> FF(%) PCE(%) Example 2 1.168 23.78 80.56 22.38 Example 3 1.146 23.06 78.79 20.82 Example 4 1.139 23.21 77.56 20.50 Example 5 1.153 22.92 79.82 21.09 Example 6 1.147 23.12 79.72 21.14 Example 7 1.161 23.34 80.39 21.78 Example 8 1.173 23.42 80.21 22.04 Example 9 1.169 23.72 80.64 22.36 Comparative Example 1.117 22.74 77.12 19.59

[0169] Data analysis

[0170] By comparing the performance parameters of the solar cell devices prepared by different embodiments and comparative examples in Table 1, it can be seen that the conversion efficiency of the perovskite solar cell devices prepared by Examples 2 to 9 is higher than that of the perovskite solar cell devices prepared by the comparative examples, indicating that the scheme of the present invention can effectively improve the efficiency of the perovskite solar cell devices and has significant beneficial effects. Among them, the performance improvement is due to the mercaptothiazole material regulating the crystallization process of the two-step metal halide perovskite film, promoting the complete reaction of the two-step process, promoting the crystallization growth of the metal halide perovskite film, and passivating the defects of the perovskite bulk phase and the surface interface, thereby improving the conversion efficiency of the device.

[0171] Analysis of the data of Examples 2-4 and the comparative example in Table 1 shows that adding the mercaptothiazole material alone to the metal halide precursor solution in the two-step perovskite precursor solution and depositing it on the surface of the metal halide perovskite film can both improve the performance of the perovskite solar cell device. Combining the two methods can play a synergistic role and further improve the performance of the perovskite solar cell device.

[0172] Figure 4 is the X-ray diffraction pattern of the metal halide perovskite film prepared in Example 2, Figure 5 The X-ray diffraction spectrum of the metal halide perovskite film prepared in the comparative example, wherein the model of the X-ray diffractometer is Rigaku, D / max2500VB25 / PC, and the characteristic diffraction peaks belonging to the (110) and (220) crystal planes of the perovskite material are marked in the figure, and the * is marked as the characteristic diffraction peak belonging to lead iodide. Figure 4 , Figure 5 It can be found that the characteristic diffraction peak intensity of the metal halide perovskite film in Example 2 is significantly stronger than that of the metal halide perovskite film in the comparative example. At the same time, the characteristic peak intensity attributable to lead iodide near 12.7 degrees is significantly weakened, indicating that introducing the mercaptothiazole material into the metal halide solution in the two-step perovskite precursor solution can promote the full reaction between the precursors, regulate the crystallization process of the metal halide perovskite film, and slow down the crystallization rate of the metal halide perovskite film, so that the perovskite is fully crystallized, thereby obtaining a higher quality metal halide perovskite film.

[0173] Figure 6 is an electron microscope photograph of the metal halide perovskite film in Example 2, Figure 7 The electron microscope photograph of the metal halide perovskite film prepared in the comparative example, wherein the scanning electron microscope model is JEOL-6701F, and the magnification is 30000 times. Figure 6 , Figure 7 It can be found that Figure 7 The metal halide perovskite films in the nanostructured carbon nanotubes have smaller grain sizes and holes between the grains, while Figure 6 The metal halide perovskite film in Example 2 has a larger grain size and a smoother and more compact surface morphology. The larger grain size and the smoother and non-porous surface indicate that the metal halide perovskite film in Example 2 has a lower defect state density and the device will generate less leakage current during operation, which is beneficial to the improvement of the efficiency and stability of the perovskite solar cell device.

[0174] The batteries prepared in Example 2 and the comparative example were placed in the same air under various conditions, and their JV characteristic curves were periodically measured to obtain the power conversion efficiency (PCE) of the batteries and the PCE data were normalized. The results are shown in FIG. Figure 8 As shown in Figure 2, the purpose of normalization is to facilitate the comparison of PCE data at the same starting point. Figure 8 It can be found that the battery sample prepared in Example 2 exhibits longer stability than the battery sample prepared in the comparative example, which indicates that the interfacial passivation protective layer formed by the mercaptothiazole material introduced in Example 2 can effectively protect the metal halide perovskite film from moisture erosion, thereby improving the stability of the metal halide perovskite film.

[0175] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A two-step method for preparing a perovskite precursor solution, characterized in that: include: S101, a step of preparing a metal halide precursor solution doped with mercaptothiazole: dissolving a metal halide material in a first solvent to prepare a metal halide precursor solution, Adding mercaptothiazole material to a metal halide precursor solution, heating and stirring the solution, to obtain a metal halide precursor solution doped with mercaptothiazole; S102, cationic halide precursor solution preparation step: dissolving the cationic halide material into a second solvent to obtain a cationic halide precursor solution.

2. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The mercaptothiazole material includes any one or more of 2-mercaptothiazole, 2,5-dimercaptothiazole, 2-mercapto-1,3,4-thiadiazole, and 2,5-dimercapto-1,3,4-thiadiazole.

3. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The metal halide material has a molecular formula of BX2, where B is Pb 2+ Sn 2+ One or two of X include halogen ions I - Br - , Cl - Any one or more of the .

4. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The first solvent includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

5. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The concentration of the metal halide material in the first solvent is in the range of 1.0 to 2.0M.

6. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: In step S101, the heating temperature is 30 to 60°C.

7. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The cationic halide material has the molecular formula AX, A is CH3NH3 + 、CH(NH2)2 + 、(CH3)2NH2 + , Cs + Any one or more of the following, X is a halogen ion I - Br - , Cl - Any one or more of the .

8. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The second solvent includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

9. The method for preparing a two-step perovskite precursor solution according to claim 1, characterized in that: The concentration of the cationic halide material in the second solvent is in the range of 1.0 to 2.0 M.

10. A two-step perovskite precursor solution, characterized in that: The invention comprises a metal halide precursor solution and a cationic halide precursor solution doped with mercaptothiazole prepared by the method described in any one of claims 1 to 9.

11. A method for preparing a metal halide perovskite thin film, characterized in that: include: S201, coating a metal halide precursor solution doped with mercaptothiazole prepared by the method according to any one of claims 1 to 9 on a substrate, and annealing to obtain a metal halide layer; S202, coating the cationic halide precursor solution obtained by the method described in any one of claims 1 to 9 on the metal halide layer, and annealing to obtain a metal halide perovskite film.

12. The method for preparing a metal halide perovskite thin film according to claim 11, characterized in that: Also includes: S203, preparing a mercaptothiazole material solution, depositing it on the surface of the metal halide perovskite film, and annealing to form an interface protection layer on the surface of the metal halide perovskite film.

13. The method for preparing a metal halide perovskite thin film according to claim 11 or 12, characterized in that: In step S201, the annealing temperature is 50-100°C, and the annealing time is 0.1-5 minutes.

14. The method for preparing a metal halide perovskite thin film according to claim 11 or 12, characterized in that: In step S202, the annealing temperature is 90-250°C, and the annealing time is 5-20 minutes.

15. The method for preparing a metal halide perovskite thin film according to claim 12, characterized in that: In step S203, the solvent used in preparing the mercaptothiazole material solution includes an organic solvent, and the organic solvent includes any one or more of ethanol, isopropanol, toluene, chlorobenzene, chloroform, ether, N,N-dimethylformamide, and dimethyl sulfoxide.

16. The method for preparing a metal halide perovskite thin film according to claim 12, characterized in that: In step S203, the solvent in the mercaptothiazole material solution is chlorobenzene, and the concentration thereof is 0.1-10 mg / mL.

17. The method for preparing a metal halide perovskite thin film according to claim 12, characterized in that: In step S203, the annealing temperature is 60-120°C, and the annealing time is 1-10 minutes.

18. A metal halide perovskite film, characterized in that: The method according to any one of claims 11 to 17 is used to prepare the present invention.

19. A perovskite solar cell, characterized in that: From bottom to top, it includes a conductive substrate, a first carrier transport layer, the metal halide perovskite film according to claim 18, a second carrier transport layer, a buffer layer and an electrode layer.

20. The perovskite solar cell according to claim 19, characterized in that: The metal halide perovskite film comprises a perovskite light absorbing layer and an interface passivation protective layer, and the interface passivation protective layer is deposited on the surface of the perovskite light absorbing layer.

21. The perovskite solar cell according to claim 20, characterized in that: The thickness of the perovskite light-absorbing layer is 200-1000 nm.

22. The perovskite solar cell according to claim 20, characterized in that: The thickness of the interface passivation protection layer is 2-40 nm.

23. The perovskite solar cell according to claim 19, characterized in that: The conductive substrate includes any one of ITO, FTO and AZO.

24. The perovskite solar cell according to claim 19, characterized in that: The first carrier transport layer is a hole transport layer, and the second carrier transport layer is an electron transport layer; or, the first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer; The material of the hole transport layer is [2-(9H-carbazole-9-yl)ethyl]phosphate (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphate (MeO-2PACz), [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphate (Me-2PACz), [4-(9H-carbazole-9-yl)butyl]phosphate (4PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphate (MeO-4PACz), [ 4-(7H-dibenzocarbazole-7-yl)butyl]phosphoric acid (4PADCB), 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 2,2',7,7'-tetrakis[N,N-di(4-methylphenyl)amino]-9,9'-spirobifluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3-hexylthiophene-2,5-diyl) (P3HT), poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD), nickel oxide (NiO x ), cuprous thiocyanate (CuSCN), copper iodide (CuI); The material of the electron transport layer includes C 60 , any one of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), tin oxide (SnO2), zinc oxide (ZnO), and titanium oxide (TiO2).

25. The perovskite solar cell according to claim 19, characterized in that: The thickness of the first carrier transport layer is 1 to 100 nm, and the thickness of the second carrier transport layer is 1 to 100 nm.

26. The perovskite solar cell according to claim 19, characterized in that: The material of the buffer layer is SnO2 or 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP).

27. The perovskite solar cell according to claim 19, characterized in that: The thickness of the buffer layer is 1-10 nm.

28. The perovskite solar cell according to claim 19, characterized in that: The electrode layer is a metal electrode layer, the material of the electrode layer includes any one of gold, silver and copper, and the thickness of the electrode layer is 70-150 nm.

29. A method for preparing a perovskite solar cell, characterized in that: include: depositing a first carrier transport layer on a conductive substrate; Taking the first carrier transport layer as a substrate, depositing a metal halide perovskite film on the first carrier transport layer by the method described in any one of claims 11 to 17; A second carrier transport layer, a buffer layer, and an electrode layer are sequentially deposited on the metal halide perovskite film to obtain a perovskite solar cell.

30. The method for preparing a perovskite solar cell according to claim 29, characterized in that: The deposition method of the first carrier transport layer and the second carrier transport layer includes any one of coating, thermal evaporation and magnetron sputtering.

31. The method for preparing a perovskite solar cell according to claim 29, characterized in that: The coating includes any one of spin coating, spray coating, blade coating and slit coating.

32. The method for preparing a perovskite solar cell according to claim 29, characterized in that: The electrode layer is deposited by thermal evaporation at a deposition rate of

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