Perovskite photoactive layer preparation method based on 2D perovskite confinement directional growth, solar cell and preparation method

Abstract

The invention relates to the technical field of photoelectric functional materials and devices, and provides a preparation method of a perovskite photoactive layer based on 2D perovskite confinement directional growth, a solar cell and a preparation method.The grain size of a perovskite body is adjusted through formamidine formate, and a gap is generated at the grain boundary; preliminary passivation is carried out through lead thiocyanate, and in the film forming process, after thiocyanate radicals are released, lead iodide is formed at the grain boundary; guanidino iodide is adopted for post-treatment and reacts with lead iodide at the grain boundary, and confinement oriented growth of the 2D perovskite is achieved. According to the invention, on the basis of generation of grain boundary gaps through double doping and completion of preliminary passivation of lead iodide, guanidino iodine is adopted for post-treatment, so that the film quality can be effectively improved, the photoelectric conversion efficiency and filling factors of a device are improved, and efficient and stable perovskite unijunction solar cells and perovskite / organic laminated solar cells are obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic functional materials and devices, and in particular to a method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth, a solar cell and a preparation method thereof. Background Art

[0002] Perovskite solar cells are known for their unique ABX3 perovskite structure, where A represents a monovalent cation, B represents a divalent metal cation, and X represents a halogen anion. Compared with traditional silicon-based solar cells, perovskite solar cells show higher flexibility and convenience in the preparation process, and can be produced using low-cost methods such as the solution method. It is particularly worth mentioning that due to the flexibility of its preparation process, perovskite solar cells can be easily mounted on flexible substrates, thus achieving wide applications in various fields such as curved, foldable and wearable electronic devices, opening up a new path for the future development of photovoltaic technology.

[0003] Tandem solar cells are devices that use multiple light-absorbing layers to effectively utilize photons of different wavelengths in the solar spectrum, and can effectively suppress energy loss caused by hot carrier relaxation, thereby breaking through the theoretical limit of single-junction cell SQ for photoelectric conversion efficiency. Currently, tandem solar cells based on perovskite / silicon, perovskite / copper indium gallium selenide (CIGS) and all-perovskite have been widely studied.

[0004] Perovskite has important application potential in tandem solar cells. The crystallization rate of perovskite during the film preparation process will affect the final film quality. An unsatisfactory crystallization process may lead to a higher defect state density, especially defects at the grain boundaries, which may significantly affect device performance. Compared with 3D perovskite solar cells, the photoelectric conversion efficiency of 2D perovskite is still at a low level.

[0005] Previous studies have shown that smaller grain sizes in thin films are often accompanied by a large number of grain boundaries, and the grain boundaries of perovskites can induce non-radiative recombination and ion migration. At present, there are very mature methods for surface passivation of perovskites, but there are relatively few studies on passivation of grain boundaries using 2D perovskite phase confinement. Increasing grain size, optimizing grain boundary structure, and reducing non-radiative recombination are key ways to improve the performance of perovskite solar cells. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth, a solar cell and a preparation method, by introducing dual doping of formamidine formate (FAFa) and lead thiocyanate (Pb(SCN)2) into the perovskite precursor solution. FAFa can regulate the crystallization process of perovskite. Scanning electron microscopy (SEM) testing found that the doped grain size increased significantly and gaps were generated at the grain boundaries. Therefore, Pb(SCN)2 was selected to fill the gaps without changing the band gap, that is, without introducing other halogen ions. During the film formation process, SCN - After release, lead iodide (PbI2) is formed at the grain boundaries for initial passivation.

[0007] On the basis of the dual doping to produce grain boundary gaps and complete the initial passivation of PbI2, guanidinium iodine (GAI) is used for post-treatment to react with the above PbI2 at the grain boundary to achieve the confined directional growth of 2D perovskite. This post-treatment can effectively improve the film quality, while improving the photoelectric conversion efficiency and fill factor of the device, and obtain efficient and stable perovskite solar cells. In addition, this strategy is also applicable to perovskite / organic tandem solar cells.

[0008] The present invention provides a method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth, comprising: S101: using a precision balance, weighing 0.1-0.3 mg of lead iodide, 0.1-0.3 mg of lead bromide, 0.02-0.3 mg of cesium iodide, and 0.05-0.3 mg of formamidine hydroiodide in 1 ml of a first organic solvent, and stirring until completely dissolved to prepare a perovskite precursor solution; S102: using a precision balance, weigh 0.5-40 mg of formamidine formate and 0.3-10 mg of lead thiocyanate, and dissolve them in 1 ml of the perovskite precursor solution until they are completely dissolved to prepare a prefabricated solution; S103: spin coating the prepared prefabricated liquid on the prepared perovskite body at a rotation speed of 1000-8000 rpm for 10-60 s, and annealing to form a perovskite photoactive layer; S104: using a precision balance to weigh 0.1-10 mg of guanidino iodine and dissolving it in 1 ml of a second organic solvent, heating and stirring at 10-80° C. until completely dissolved to prepare a guanidino iodine solution; S105: Spin coating the prepared guanidine iodine solution on the prepared perovskite photoactive layer at a rotation speed of 1000-8000 rpm for 10-60 s, and annealing to obtain a perovskite photoactive layer based on 2D perovskite confined directional growth.

[0009] Furthermore, the annealing temperature is 50-150° C., and the annealing time is 3-30 min.

[0010] Furthermore, the first organic solvent is dimethylformamide and / or dimethyl sulfoxide, and the second organic solvent is isopropanol.

[0011] The present invention also provides a solar cell, which is a perovskite single-junction solar cell based on the confined directional growth of 2D perovskite or a perovskite / organic tandem solar cell based on the confined directional growth of 2D perovskite, and the solar cell includes the perovskite photoactive layer based on the confined directional growth of 2D perovskite.

[0012] Furthermore, the perovskite single-junction solar cell based on the confined and directional growth of 2D perovskite includes a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer based on the confined and directional growth of 2D perovskite, a PEAI modification layer, an electron transport layer and a metal electrode stacked in sequence.

[0013] Furthermore, a method for preparing a perovskite single-junction solar cell based on 2D perovskite confined directional growth is provided. S201: treating the cleaned ITO glass of the transparent conductive substrate with ozone, spin coating the nickel oxide solution at a rotation speed of 1000-8000 rpm for 10-60s, and annealing at 80-180°C for 5-50 min to obtain a hole transport layer; S202: spin-coating the [2-(9H-carbazole-9-yl)ethyl]phosphoric acid solution on the hole transport layer at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180°C for 5-50 minutes to obtain a self-assembled monolayer; S203: forming a perovskite photoactive layer based on 2D perovskite confined directional growth on the self-assembled monolayer; S204: spin coating the phenylethylammonium iodide solution on the perovskite photoactive layer based on the 2D perovskite confined directional growth at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180° C. for 5-50 minutes to obtain a PEAI modified layer; S205: Spin-coating a phenyl C-61 butyrate methyl ester solution on the PEAI modified layer at a rotation speed of 1000-8000 rpm for 10-60 seconds to obtain an electron transport layer; S206: spin-coating the 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline supernatant on the electron transport layer at a rotation speed of 1000-8000 rpm for 10-60 s; S207: evaporating 50-150 nm of Ag electrode on the electron transport layer under vacuum conditions to obtain a metal electrode; Through steps S201 to S207, a perovskite single-junction solar cell based on 2D perovskite confined directional growth is prepared.

[0014] The present invention also provides a perovskite / organic tandem solar cell prepared based on a confined directional growth strategy of 2D perovskite, including a perovskite photoactive layer based on the confined directional growth of 2D perovskite.

[0015] Furthermore, a perovskite / organic tandem solar cell prepared based on the confined directional growth strategy of 2D perovskite includes a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer based on the confined directional growth of 2D perovskite, a PEAI modification layer, an electron transport layer, an Ag / Au interconnection layer, a hole transport layer, a PM6:Y6:PCBM ternary heterojunction layer, an electron transport layer and an Ag metal electrode stacked in sequence.

[0016] Furthermore, a method for preparing a perovskite / organic tandem solar cell based on a confined directional growth strategy of 2D perovskite is provided. S301: treating the cleaned ITO glass of the transparent conductive substrate with ozone, spin coating the nickel oxide solution at a speed of 1000-8000 rpm for 10-60s, and annealing at 80-180°C for 5-50 min to obtain a hole transport layer; S302: spin-coating the [2-(9H-carbazole-9-yl)ethyl]phosphoric acid solution on the hole transport layer at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180° C. for 5-50 minutes to obtain a self-assembled monolayer; S303: forming a perovskite photoactive layer based on 2D perovskite confined directional growth on the self-assembled monolayer; S304: spin-coating the phenylethylammonium iodide solution on the perovskite photoactive layer based on the 2D perovskite confined directional growth at a rotation speed of 1000-8000 rpm for 10-60s, and annealing at 50-180°C for 5-50 min to obtain a PEAI modified layer; S305: spin coating the phenyl C-61 butyrate methyl ester solution on the PEAI modified layer at a rotation speed of 1000-8000 rpm for 10-60s to obtain an electron transport layer; S306: spin-coating the 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline supernatant on the electron transport layer at a rotation speed of 1000-8000 rpm for 10-60s; S307: evaporating the Ag / Au interconnection layer and the molybdenum trioxide layer under vacuum conditions to obtain the Ag / Au interconnection layer; S308: spin coating the ternary PM6:Y6:PCBM organic solution on the molybdenum trioxide layer at a rotation speed of 1000-8000 rpm for 20-80s, and annealing at 50-180°C for 5-50 min to obtain a PM6:Y6:PCBM ternary body heterojunction layer; S309: Spin-coat a poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide solution on the PM6:Y6:PCBM ternary heterojunction layer at a rotation speed of 1000-8000 rpm for 10-60s; S310: evaporating 50-150 nm of Ag electrode on the poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide layer under vacuum conditions to obtain an Ag metal electrode; After step S301 to step S310, a perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite is prepared; Among them, PM6 is poly[[4,8-bis[4-fluoro-5-(2-ethylhexyl)-thiophene-2-yl-]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-alt-[5,7-bis-(2-ethylhexyl)benzo[1,2-c:4,5-c']dithiophene-4,8-dione-1,3-dithiophene-5',5''-diyl], Y6 is 2,2'-(((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, PCBM is [6,6]-phenyl C61 butyric acid methyl ester.

[0017] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The present invention provides a confined directional growth strategy for 2D perovskite, which is to dope formamidine formate (FAFa) and lead thiocyanate (Pb(SCN)2) in the perovskite photoactive layer. FAFa regulates the perovskite crystallization process, obtains large-sized, well-oriented grains, and leaves grain boundary gaps. Without introducing other halogen ions, Pb(SCN)2 is used to preliminarily passivate the grain boundaries. During the film formation process, SCN -After release, lead iodide PbI2 is formed at the grain boundary to complete the initial passivation. Then, at the grain boundary, guanidino iodine (GAI) is post-treated with the above PbI2 to obtain a confined and directional growth 2D perovskite phase. This strategy can also improve the position of the bottom of the conduction band and the top of the valence band of the perovskite, while raising the Fermi level, promoting electron transport at the i / n interface, and enhancing the blocking effect on holes. The present invention provides a new idea for the crystallization regulation and grain boundary passivation of perovskite solar cells, and provides a broad prospect for further improving the performance of perovskite solar cells and perovskite / organic tandem solar cells.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of a perovskite single-junction solar cell based on 2D perovskite confined and directional growth provided by the present invention.

[0021] Figure 2 3 are scanning electron microscope (SEM) images of the perovskite film before and after modification under different conditions in the embodiments of the present invention.

[0022] Figure 3 : The normalized X-ray diffraction (XRD) spectra of the perovskite film before and after modification under different conditions in the embodiments of the present invention, as well as the peak intensity ratio of the perovskite (100) plane to lead iodide.

[0023] Figure 4 GIWAXS spectra of the perovskite film before and after modification under different conditions in the embodiments of the present invention.

[0024] Figure 5 The photoluminescence spectra (PL) and time-resolved fluorescence spectra (TRPL) of the perovskite film before and after modification under different conditions in the embodiments of the present invention are shown.

[0025] Figure 6 1 and 2 are dark current curves of the device before and after modification under different conditions in the embodiment of the present invention.

[0026] Figure 7 1 is the JV curve of the perovskite solar cell before and after modification under different conditions in the embodiment of the present invention.

[0027] Figure 8 1 is the JV curve of the perovskite / organic tandem solar cell before and after modification under different conditions in the embodiment of the present invention.

[0028] Reference numerals: 1. Transparent conductive substrate; 2. Hole transport layer; 3. Self-assembled monolayer; 4. Perovskite photoactive layer based on 2D perovskite confined directional growth; 5. PEAI modification layer; 6. Electron transport layer; 7. Metal electrode. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0031] Combine the following Figures 1 to 8 The present invention describes a method for preparing a perovskite photoactive layer based on 2D perovskite confined and directional growth, a solar cell and a preparation method thereof.

[0032] The perovskite photoactive layer includes a perovskite host, formamidine formate (FAFa), lead thiocyanate (Pb(SCN)2), and guanidino iodine (GAI); The grain size of the perovskite host is adjusted by FAFa, and gaps are generated at the grain boundaries; Preliminary passivation is performed by (Pb(SCN)2). During the film formation process, SCN - After release, lead iodide (PbI2) is formed at the grain boundaries; GAI is used for post-treatment to react with PbI2 at the grain boundaries to achieve confined and directional growth of 2D perovskite.

[0033] The molecular structure of formamidine formate is The molecular structure of lead thiocyanate is The molecular structure of guanidino iodine is .

[0034] A method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth, comprising: S101: using a precision balance, weigh 0.1-0.3 mg PbI2, 0.1-0.3 mg lead bromide (PbBr2), 0.02-0.3 mg cesium iodide (CsI), and 0.05-0.3 mg formamidine hydroiodide (FAI) in 1 ml of a first organic solvent, and stir until completely dissolved to prepare a perovskite precursor solution; the first organic solvent includes but is not limited to dimethylformamide and / or dimethyl sulfoxide (DMF and DMSO); S102: using a precision balance, weigh 0.5-40 mg of FAFa and 0.3-10 mg of Pb(SCN)2, and dissolve them in 1 ml of the perovskite precursor solution until they are completely dissolved to prepare a prefabricated solution; S103: spin coating the prepared prefabricated liquid on the prepared perovskite body at a rotation speed of 1000-8000 rpm for 10-60 s, and annealing to form a perovskite photoactive layer; S104: using a precision gradient balance to weigh 0.1-10 mg of GAI and dissolving it in 1 ml of a second organic solvent, heating and stirring at 10-80° C. until completely dissolved to prepare a guanidino iodine solution; the second organic solvent includes isopropyl alcohol (IPA), but is not limited to IPA; S105: spin coating the prepared GAI solution on the prepared perovskite photoactive layer at a rotation speed of 1000-8000 rpm for 10-60 s, and performing annealing treatment to obtain a perovskite photoactive layer based on 2D perovskite confined directional growth.

[0035] Annealing is the process of heating to an appropriate temperature, keeping it at that temperature for a certain period of time, and then slowly cooling it.

[0036] The annealing treatment of the perovskite photoactive layer preparation method based on 2D perovskite confined directional growth of the present invention is heating to 50-150° C. and keeping the temperature for 3-30 min.

[0037] The heating temperature of the annealing treatment is 50-150°C, and can be 50°C, 100°C, or 150°C.

[0038] The holding time of the annealing treatment is 3-30 min, which can be selected as 3 min, 15 min, 25 min, and 30 min.

[0039] like Figure 1 As shown, a perovskite single-junction solar cell based on 2D perovskite confined directional growth includes a transparent conductive substrate 1, a hole transport layer 2, a self-assembled monolayer 3, a perovskite photoactive layer 4 based on 2D perovskite confined directional growth, a PEAI modified layer 5, an electron transport layer 6 and a metal electrode 7 stacked in sequence.

[0040] A method for preparing a perovskite single-junction solar cell based on 2D perovskite confined directional growth, comprising: S201: The cleaned ITO glass of the transparent conductive substrate 1 is subjected to ozone treatment, and nickel oxide (NiO x ) solution for 10-60s, annealing at 80-180°C for 5-50 min to obtain a hole transport layer 2; S202: Spin-coat [2-(9H-carbazole-9-yl)ethyl]phosphoric acid solution (2PACz) on the hole transport layer 2 at a rotation speed of 1000-8000 rpm for 10-60 seconds, and anneal at 50-180°C for 5-50 minutes to obtain a self-assembled monolayer 3; S203: forming a perovskite photoactive layer 4 based on 2D perovskite confined directional growth on the self-assembled monolayer 3; S204: Spin-coating a phenylethylammonium iodide (PEAI) solution on the perovskite photoactive layer 4 based on 2D perovskite confined directional growth at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180° C. for 5-50 minutes to obtain a PEAI modified layer 5; S205: Spin-coating a phenyl C-61 butyric acid methyl ester (PCBM) solution on the PEAI modified layer 5 at a rotation speed of 1000-8000 rpm for 10-60 seconds to obtain an electron transport layer 6; S206: Spin-coat the 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) supernatant on the electron transport layer 6 at a speed of 1000-8000 rpm for 10-60 seconds; S207: Evaporate 50-150 nm of Ag electrode onto the BCP layer under vacuum conditions to obtain a metal electrode 7.

[0041] After steps S201 to S207, a perovskite single-junction solar cell based on 2D perovskite confined directional growth is obtained.

[0042] A perovskite / organic tandem solar cell prepared based on a confined directional growth strategy of 2D perovskite, comprising a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer, a PEAI modification layer, an electron transport layer, an Ag / Au interconnection layer, a hole transport layer, a PM6:Y6:PCBM ternary heterojunction layer, an electron transport layer and an Ag metal electrode stacked in sequence.

[0043] A method for preparing a perovskite / organic tandem solar cell based on a confined directional growth strategy of 2D perovskite, comprising: S301: The cleaned ITO glass substrate is subjected to ozone treatment, and nickel oxide (NiO x ) solution for 10-60s, annealing at 80-180°C for 5-50 min to obtain a hole transport layer; S302: Spin-coat the 2PACz solution on the hole transport layer at a rotation speed of 1000-8000 rpm for 10-60 seconds, and anneal at 50-180° C. for 5-50 minutes to obtain a self-assembled monolayer; S303: coating on the self-assembled monolayer to form a perovskite photoactive layer based on 2D perovskite confined directional growth; S304: Spin-coating a phenylethylammonium iodide (PEAI) solution on the perovskite photoactive layer based on 2D perovskite confined directional growth at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180 °C for 5-50 minutes to obtain a PEAI modified layer; S305: Spin-coating a phenyl C-61 butyric acid methyl ester (PCBM) solution on the PEAI modified layer at a rotation speed of 1000-8000 rpm for 10-60 seconds to obtain an electron transport layer; S306: Spin-coat the 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) supernatant on the electron transport layer at a speed of 1000-8000 rpm; spin-coating for 10-60 seconds. S307: evaporating the Ag / Au interconnection layer and the molybdenum trioxide layer (MoO3) under vacuum conditions to obtain the Ag / Au interconnection layer; S308: spin coating the ternary PM6:Y6:PCBM organic solution on the MoO3 layer at a rotation speed of 1000-8000 rpm for 20-80s, and annealing at 50-180°C for 5-50 min to obtain a PM6:Y6:PCBM ternary body heterojunction layer; S309: spin coating the PFN-Br solution on the PM6:Y6:PCBM ternary heterojunction layer at a rotation speed of 1000-8000 rpm for 10-60s; S310: evaporating 50-150 nm of Ag electrode on the PFN-Br layer under vacuum conditions to obtain an Ag metal electrode; After steps S301 to S310, a perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite is obtained; Among them, PM6 is poly[[4,8-bis[4-fluoro-5-(2-ethylhexyl)-thiophene-2-yl-]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-alt-[5,7-bis-(2-ethylhexyl)benzo[1,2-c:4,5-c']dithiophene-4,8-dione-1,3-dithiophene-5',5''-diyl], Y6 is 2,2'-(((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, PCBM is [6,6]-phenyl C61 butyric acid methyl ester.

[0044] Example: The C=O in the FAFa additive of the present invention can react with Pb 2+ The interaction of ions hinders the formation of large iodine lead salt colloids, which helps to obtain large-sized perovskite grains while leaving grain boundary gaps. Pb(SCN)2 additives can effectively fill the gaps between large grains. - It is released in the form of gas during the film formation process and will not be embedded in the perovskite lattice, leaving PbI2 at the grain boundary as a preliminary passivation. GAI can interact with PbI2 at the grain boundary to eventually generate a 2D perovskite phase with confined and directional growth, achieving efficient passivation of grain boundary defects while maintaining good electrical properties. The present invention achieves confined and directional growth of 2D perovskite by adopting a sequential optimization method, thereby greatly improving the optical and electrical properties of solar cells.

[0045] The steps for preparing the film of the present invention are as follows: weigh 30 mg of FAFa with a precision balance and put it into vial No. 1, weigh 30 mg of FAFa and 4.8 mg of Pb(SCN)2 and put them into vial No. 2, then add 1 mL of fully dissolved perovskite precursor solution to each of the two vials, stir at room temperature until completely dissolved, and obtain a clear and transparent yellow solution. Weigh 2.9 mg of GAI with a precision balance and put it into vial No. 3, add 1 mL of IPA to the vial, stir at 50°C until completely dissolved, and obtain a clear and transparent colorless solution. The film without any optimization is marked as control, the film containing only FAFa additive is marked as FAFa, the film containing both FAFa and Pb(SCN)2 additives is marked as FAFa&Pb(SCN)2, and the film containing both FAFa and Pb(SCN)2 additives and using GAI passivator is marked as FAFa&Pb(SCN)2+GAI.

[0046] The steps for preparing the device described in the present invention are as follows: weigh 2.4 mg of FAFa and 0.8 mg of Pb(SCN)2 with a precision balance, put them into a vial, add 1 mL of fully dissolved perovskite precursor solution into the vial, stir at room temperature until completely dissolved, and obtain a clear and transparent yellow solution. Weigh 1 mg of GAI with a precision balance and put it into a vial, add 2 mL of IPA into the vial, stir at 50°C until completely dissolved, and obtain a clear and transparent colorless solution. The device without any optimization is marked as control, and the device containing both FAFa and Pb(SCN)2 additives and using a GAI passivator is marked as FAFa&Pb(SCN)2+GAI.

[0047] FAFa additives can change the grain size of perovskite. In order to study the effect of FAFa treatment on the crystallization process of perovskite, the present invention conducted SEM tests on the perovskite film with FAFa added, such as Figure 2 As shown in (a), the grains of the perovskite film without FAFa solution treatment are very small, such as Figure 2 (b) and Figure 2 As shown in (e), after adding FAFa, the perovskite grains are significantly enlarged, and gaps appear at the grain boundaries, such as Figure 3 The XRD spectrum shown in (a) shows that after adding FAFa, the perovskite is crystallized in the (100) plane orientation.

[0048] like Figure 2 As shown in (c), the FAFa & Pb(SCN)2 dual additives can change the grain size of the perovskite and initially fill the grain boundary gaps. Adding Pb(SCN)2 can effectively fill the grain boundary cracks. Figure 3(b) shows the XRD spectrum. After adding Pb(SCN)2, the PbI2 peak intensity in the perovskite film is enhanced. Figure 4 As shown in (b), q z ≈ 0.92 Å −1 The signal at corresponds to the (001) plane of PbI2, indicating the formation of PbI2 at the grain boundary.

[0049] GAI solution can react with PbI2 at the grain boundaries to achieve confined directional growth of 2D perovskite phase, such as Figure 2 As shown in (d), new phases appeared at the grain boundaries of perovskite after GAI solution treatment, such as Figure 4 As shown in (a) and (c), after treatment with GAI solution, z ≈ 0.79 Å −1 The diffraction rings of the 2D perovskite phase appeared at 30.14° and 69.97°, indicating that the 2D perovskite phase tends to grow at 59.86° and 20.03° to the substrate. At this point, the confined directional growth of the 2D perovskite is completed.

[0050] The confined directional growth strategy of FAFa&Pb(SCN)2+GAI 2D perovskite can reduce the non-radiative recombination of perovskite and prolong the carrier lifetime. The present invention conducts fluorescence spectroscopy (PL) and time-resolved fluorescence spectroscopy tests on perovskite films with and without the synergistic optimization strategy, and the test structure is glass / perovskite. Figure 5 The peak position of PL before and after optimization does not change significantly, indicating that the additive is not embedded in the perovskite structure. After optimization, the PL peak intensity is significantly enhanced, and the corresponding carrier lifetime obtained after TRPL fitting is also significantly extended. After optimization, the perovskite grain size increases, resulting in a decrease in grain boundaries in the same area of ​​film, where non-radiative recombination of carriers and ion migration are most likely to occur. This optimization strategy not only reduces the grain boundaries but also effectively passivates the grain boundaries, which helps to efficiently transport photogenerated carriers.

[0051] The confined directional growth strategy of FAFa&Pb(SCN)2+GAI 2D perovskite can reduce the dark state leakage current of solar cells. The present invention conducts dark state JV tests on perovskite solar cells with and without the synergistic optimization strategy. Figure 6 The dark state current of the optimized device is significantly reduced, indicating the reduction of defect states in the device, which is consistent with the SEM and PL results. The confined directional growth strategy of 2D perovskite can optimize the performance of perovskite solar cell devices. The present invention adopts a one-step anti-solvent method to prepare a perovskite single-junction solar cell, and its device structure is ITO / NiOx / 2PACz / perovskite photoactive layer / PEAI / PCBM / BCP / Ag. Under one sunlight (AM1.5G, 100 mW / cm 2), the effective area is 0.08875cm 2 As shown in Table 1, the key photovoltaic parameters of the perovskite single junction solar cell before and after optimization; Table 1 Key photovoltaic parameters of perovskite single-junction solar cells before and after optimization

[0052] Finally, an efficiency of 18.06% and a current of 17.16 mA / cm 2 The current density, open circuit voltage of 1283 mV and fill factor of 81.97% are shown in Table 1. Figure 7 As shown, the confined directional growth strategy of 2D perovskites can significantly improve the performance of devices.

[0053] The confined directional growth strategy of 2D perovskites is also applicable to perovskite / organic tandem solar cells. As shown in Table 2, the key photovoltaic parameters of perovskite / organic tandem solar cells before and after optimization of the confined directional growth strategy of 2D perovskites; Table 2 Key photovoltaic parameters of perovskite / organic tandem solar cells before and after optimization

[0054] like Figure 8 As shown, the optimized tandem cell with confined directional growth strategy of 2D perovskite achieved an efficiency of 22.41% and a fill factor of 75.54.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth, characterized in that: include: S101: using a precision balance, weighing 0.1-0.3 mg of lead iodide, 0.1-0.3 mg of lead bromide, 0.02-0.3 mg of cesium iodide, and 0.05-0.3 mg of formamidine hydroiodide in 1 ml of a first organic solvent, and stirring until completely dissolved to prepare a perovskite precursor solution; S102: using a precision balance, weigh 0.5-40 mg of formamidine formate and 0.3-10 mg of lead thiocyanate, and dissolve them in 1 ml of the perovskite precursor solution until they are completely dissolved to prepare a prefabricated solution; S103: spin coating the prepared prefabricated liquid on the prepared perovskite body at a rotation speed of 1000-8000 rpm for 10-60 s, and performing annealing treatment to form a perovskite photoactive layer; S104: using a precision balance to weigh 0.1-10 mg of guanidino iodine and dissolving it in 1 ml of a second organic solvent, heating and stirring at 10-80° C. until completely dissolved to prepare a guanidino iodine solution; S105: Spin coating the prepared guanidine iodine solution on the prepared perovskite photoactive layer at a rotation speed of 1000-8000 rpm for 10-60 s, and annealing to obtain a perovskite photoactive layer based on 2D perovskite confined directional growth.

2. According to claim 1, a method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth, characterized in that: The annealing treatment temperature is 50-150° C., and the annealing treatment time is 3-30 min.

3. The method for preparing a perovskite photoactive layer based on 2D perovskite confined directional growth according to claim 1, characterized in that: The first organic solvent is dimethylformamide and / or dimethyl sulfoxide, and the second organic solvent is isopropanol.

4. A solar cell, characterized in that: The solar cell is a perovskite single-junction solar cell based on the confined directional growth of 2D perovskite or a perovskite / organic tandem solar cell based on the confined directional growth of 2D perovskite, and the solar cell comprises the perovskite photoactive layer based on the confined directional growth of 2D perovskite according to any one of claims 1 to 3.

5. The solar cell according to claim 4, characterized in that: The perovskite single-junction solar cell based on the confined and directional growth of 2D perovskite includes a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer based on the confined and directional growth of 2D perovskite, a PEAI modification layer, an electron transport layer and a metal electrode stacked in sequence.

6. The solar cell according to claim 5, characterized in that: The preparation method of perovskite single-junction solar cell based on 2D perovskite confined directional growth is: S201: treating the cleaned ITO glass of the transparent conductive substrate with ozone, spin coating the nickel oxide solution at a rotation speed of 1000-8000 rpm for 10-60s, and annealing at 80-180°C for 5-50 min to obtain a hole transport layer; S202: spin-coating the [2-(9H-carbazole-9-yl)ethyl]phosphoric acid solution on the hole transport layer at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180°C for 5-50 minutes to obtain a self-assembled monolayer; S203: forming a perovskite photoactive layer based on 2D perovskite confined directional growth on the self-assembled monolayer; S204: spin coating the phenylethylammonium iodide solution on the perovskite photoactive layer based on the 2D perovskite confined directional growth at a rotation speed of 1000-8000 rpm for 10-60 seconds, and annealing at 50-180° C. for 5-50 minutes to obtain a PEAI modified layer; S205: Spin-coating a phenyl C-61 butyrate methyl ester solution on the PEAI modified layer at a rotation speed of 1000-8000 rpm for 10-60 seconds to obtain an electron transport layer; S206: spin-coating the 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline supernatant on the electron transport layer at a rotation speed of 1000-8000 rpm for 10-60 s; S207: evaporating 50-150 nm of Ag electrode on the electron transport layer under vacuum conditions to obtain a metal electrode; Through steps S201 to S207, a perovskite single-junction solar cell based on 2D perovskite confined directional growth is prepared.

7. The solar cell according to claim 4, characterized in that: The perovskite / organic tandem solar cell based on the confined directional growth of 2D perovskite includes a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer based on the confined directional growth of 2D perovskite, a PEAI modification layer, an electron transport layer, an Ag / Au interconnection layer, a hole transport layer, a PM6:Y6:PCBM ternary heterojunction layer, an electron transport layer and an Ag metal electrode stacked in sequence.

8. The solar cell according to claim 7, characterized in that: The preparation method of perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite is: S301: treating the cleaned ITO glass of the transparent conductive substrate with ozone, spin coating the nickel oxide solution at a speed of 1000-8000 rpm, and annealing at 80-180°C for 5-50 min to obtain a hole transport layer; S302: spin-coating a [2-(9H-carbazole-9-yl)ethyl]phosphoric acid solution on the hole transport layer at a rotation speed of 1000-8000 rpm, and annealing at 50-180° C. for 5-50 min to obtain a self-assembled monolayer; S303: forming a perovskite photoactive layer based on 2D perovskite confined directional growth on the self-assembled monolayer; S304: spin coating the phenylethylammonium iodide solution on the perovskite photoactive layer based on the 2D perovskite confined directional growth at a rotation speed of 1000-8000 rpm, annealing at 50-180 ° C for 5-50 min to obtain a PEAI modified layer; S305: spin coating a phenyl C-61 butyrate methyl ester solution on the PEAI modified layer at a rotation speed of 1000-8000 rpm to obtain an electron transport layer; S306: spin coating the 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline supernatant on the electron transport layer at a rotation speed of 1000-8000 rpm; S307: evaporating the Ag / Au interconnection layer and the molybdenum trioxide layer under vacuum conditions to obtain the Ag / Au interconnection layer; S308: spin coating the ternary PM6:Y6:PCBM organic solution on the molybdenum trioxide layer at a rotation speed of 1000-8000 rpm for 20-80s, and annealing at 50-180°C for 5-50 min to obtain a PM6:Y6:PCBM ternary body heterojunction layer; S309: Spin-coat a poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide solution on the PM6:Y6:PCBM ternary heterojunction layer at a rotation speed of 1000-8000 rpm for 10-60s; S310: evaporating 50-150 nm of Ag electrode on the poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide layer under vacuum conditions to obtain an Ag metal electrode; After step S301 to step S310, a perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite is prepared; Among them, PM6 is poly[[4,8-bis[4-fluoro-5-(2-ethylhexyl)-thiophene-2-yl-]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-alt-[5,7-bis-(2-ethylhexyl)benzo[1,2-c:4,5-c']dithiophene-4,8-dione-1,3-dithiophene-5',5''-diyl], Y6 is 2,2'-(((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, PCBM is [6,6]-phenyl C61 butyric acid methyl ester.

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