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

Abstract

This invention relates to the field of optoelectronic functional materials and devices, providing a method for preparing a perovskite photoactive layer based on the confined directional growth of 2D perovskite, a solar cell, and a preparation method thereof. The method involves adjusting the grain size of the perovskite substrate using formamidinium formate and creating gaps at the grain boundaries; initial passivation using lead thiocyanate, during which thiocyanate ions are released and lead iodide is formed at the grain boundaries; and post-treatment using guanidino-iodine, which reacts with lead iodide at the grain boundaries, achieving the confined directional growth of 2D perovskite. This invention, based on the creation of grain boundary gaps through dual doping and the initial passivation with lead iodide, effectively improves the film quality through guanidino-iodine post-treatment, while simultaneously increasing the photoelectric conversion efficiency and fill factor of the device, resulting in highly efficient and stable perovskite single-junction solar cells and perovskite / organic tandem solar cells.

Description

Technical Field

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

[0002] Perovskite solar cells are renowned for their unique ABX3 perovskite structure, where A represents a monovalent cation, B a divalent metal cation, and X represents a halide anion. Compared to traditional silicon-based solar cells, perovskite solar cells offer greater flexibility and convenience in their fabrication processes, allowing for low-cost production using methods such as solution processing. Particularly noteworthy is their fabrication flexibility, enabling easy mounting on flexible substrates. This facilitates their widespread application in curved surfaces, foldable devices, and wearable electronic devices, paving new paths for the future development of photovoltaic technology.

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

[0004] Perovskites hold significant application potential in tandem solar cells. The crystallization rate of perovskites during thin-film fabrication affects the final film quality; an undesirable crystallization process can lead to a high defect state density, especially at grain boundaries, which can significantly impact device performance. Compared to 3D perovskite solar cells, the photoelectric conversion efficiency of 2D perovskites remains relatively low.

[0005] Previous studies have shown that smaller grain sizes in thin films are often accompanied by a large number of grain boundaries, which can induce nonradiative recombination and ion migration in perovskites. Currently, surface passivation methods for perovskites are well-established, but research on passivating grain boundaries using 2D perovskite phase confinement is relatively limited. Increasing grain size, optimizing grain boundary structure, and reducing nonradiative recombination are key approaches to improving the performance of perovskite solar cells. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in related technologies. To this end, this invention provides a method for preparing a perovskite photoactive layer based on confined directional growth of 2D perovskite, a solar cell, and a preparation method thereof, by introducing formamidine formate (FAFa) and lead thiocyanate (Pb(SCN)2) as co-doping into the perovskite precursor solution. FAFa can regulate the crystallization process of perovskite. Scanning electron microscopy (SEM) testing revealed a significant increase in grain size after doping, and the formation of gaps at grain boundaries. Therefore, Pb(SCN)2 is chosen to fill these gaps without changing the band gap, i.e., without introducing other halide ions. During the film formation process, SCN... - After release, lead iodide (PbI2) forms at the grain boundaries for initial passivation.

[0007] Based on the generation of grain boundary gaps through dual doping and the initial passivation of PbI2, guanidino-iodine (GAI) is used for post-treatment. GAI reacts with PbI2 at the grain boundaries to achieve confined, directional growth of 2D perovskite. This post-treatment effectively improves film quality, while simultaneously increasing the photoelectric conversion efficiency and fill factor of the device, resulting in a highly efficient and stable perovskite solar cell. Furthermore, this strategy is also applicable to perovskite / organic tandem solar cells.

[0008] This invention provides a method for preparing a perovskite photoactive layer based on confined directional growth of 2D perovskite, comprising:

[0009] S101: Weigh 0.1-0.3 mg lead iodide, 0.1-0.3 mg lead bromide, 0.02-0.3 mg cesium iodide, and 0.05-0.3 mg formamidin hydroiodate into 1 ml of the first organic solvent using a precision balance, and stir until completely dissolved to prepare a perovskite precursor solution;

[0010] S102: Weigh 0.5-40 mg of formamidinium formate and 0.3-10 mg of lead thiocyanate using a precision balance, and dissolve them in 1 ml of perovskite precursor solution until completely dissolved to prepare the preform solution.

[0011] S103: Spin-coat the prepared pre-mixed solution onto the prepared perovskite substrate at a speed of 1000-8000 rpm for 10-60 s, and then perform annealing treatment to form a perovskite photoactive layer.

[0012] S104: Weigh 0.1-10 mg of guanidinoiodine using a precision balance and dissolve it in 1 ml of a second organic solvent. Heat and stir at 10-80 °C until completely dissolved to prepare a guanidinoiodine solution.

[0013] S105: Spin-coat the prepared guanidino-iodine solution onto the prepared perovskite photoactive layer at a speed of 1000-8000 rpm for 10-60 s, and then perform annealing treatment to obtain a perovskite photoactive layer based on 2D perovskite confined directional growth.

[0014] Furthermore, the annealing temperature is 50-150 ℃, and the annealing time is 3-30 min.

[0015] Furthermore, the first organic solvent is dimethylformamide and / or dimethyl sulfoxide, and the second organic solvent is isopropanol.

[0016] The present invention also provides a solar cell, wherein the solar cell is a perovskite single-junction solar cell based on confined directional growth of 2D perovskite or a perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite, and the solar cell includes the perovskite photoactive layer based on confined directional growth of 2D perovskite.

[0017] Furthermore, the perovskite single-junction solar cell based on 2D perovskite confined directional growth includes a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer based on 2D perovskite confined directional growth, a PEAI modification layer, an electron transport layer, and a metal electrode stacked sequentially.

[0018] Furthermore, a method for fabricating a perovskite single-junction solar cell based on confined directional growth of 2D perovskite is provided.

[0019] S201: Ozone treatment is performed on the cleaned transparent conductive substrate ITO glass, and nickel oxide solution is spin-coated at a speed of 1000-8000 rpm for 10-60s, followed by annealing at 80-180 ℃ for 5-50 min to obtain the hole transport layer.

[0020] S202: Spin-coat a solution of [2-(9H-carbazole-9-yl)ethyl]phosphoric acid onto the hole transport layer at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180 ℃ for 5-50 min to obtain a self-assembled monolayer.

[0021] S203: A perovskite photoactive layer formed on a self-assembled monolayer based on 2D perovskite confined directional growth;

[0022] S204: Spin-coat a phenylethyl ammonium iodide solution onto a perovskite photoactive layer based on 2D perovskite confined directional growth at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180 ℃ for 5-50 min to obtain a PEAI modified layer.

[0023] S205: A methyl phenyl C-61 butyrate solution is spin-coated onto the PEAI modified layer at a speed of 1000-8000 rpm for 10-60 s to obtain an electron transport layer;

[0024] S206: Spin-coat the supernatant of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline onto the electron transport layer at a speed of 1000-8000 rpm for 10-60s;

[0025] S207: Evaporate an Ag electrode 50-150 nm into the electron transport layer under vacuum conditions to obtain a metal electrode;

[0026] Through steps S201 to S207, a perovskite single-junction solar cell based on the confined directional growth of 2D perovskite is prepared.

[0027] The present invention also provides a perovskite / organic tandem solar cell prepared by a confined directional growth strategy based on 2D perovskite, including a perovskite photoactive layer based on confined directional growth of 2D perovskite.

[0028] Furthermore, a perovskite / organic tandem solar cell fabricated based on a 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 confined directional growth of 2D perovskite, a PEAI modification layer, an electron transport layer, an Ag / Au interconnect layer, a hole transport layer, a PM6:Y6:PCBM ternary heterojunction layer, an electron transport layer, and an Ag metal electrode, stacked sequentially.

[0029] Furthermore, a method for fabricating perovskite / organic tandem solar cells based on a confined directional growth strategy for 2D perovskites is provided.

[0030] S301: Ozone treatment is performed on the cleaned transparent conductive substrate ITO glass, and nickel oxide solution is spin-coated at a speed of 1000-8000 rpm for 10-60s, followed by annealing at 80-180 ℃ for 5-50 min; hole transport layer is obtained.

[0031] S302: Spin-coat a solution of [2-(9H-carbazole-9-yl)ethyl]phosphoric acid onto the hole transport layer at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180 ℃ for 5-50 min to obtain a self-assembled monolayer.

[0032] S303: A perovskite photoactive layer formed on a self-assembled monolayer based on 2D perovskite confined directional growth;

[0033] S304: Spin-coat a phenylethyl ammonium iodide solution onto a perovskite photoactive layer based on 2D perovskite confined directional growth at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180 ℃ for 5-50 min to obtain a PEAI modified layer.

[0034] S305: A methyl phenyl C-61 butyrate solution is spin-coated onto the PEAI modified layer at a speed of 1000-8000 rpm for 10-60 s to obtain an electron transport layer;

[0035] S306: Spin-coat the supernatant of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline onto the electron transport layer at a speed of 1000-8000 rpm for 10-60s;

[0036] S307: An Ag / Au interconnect layer and a molybdenum trioxide layer are evaporated under vacuum conditions to obtain an Ag / Au interconnect layer;

[0037] S308: Spin-coat a ternary PM6:Y6:PCBM organic solution onto a molybdenum trioxide layer at a speed of 1000-8000 rpm for 20-80s, and anneal at 50-180 ℃ for 5-50 min to obtain a PM6:Y6:PCBM ternary heterojunction layer.

[0038] S309: Spin-coat a solution of poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide onto a PM6:Y6:PCBM ternary heterojunction layer at a speed of 1000-8000 rpm for 10-60 seconds;

[0039] S310: An Ag metal electrode is obtained by evaporating an Ag electrode 50-150 nm onto a poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide layer under vacuum conditions;

[0040] Steps S301 to S310 are followed to prepare perovskite / organic tandem solar cells based on confined directional growth of 2D perovskite.

[0041] 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],

[0042] Y6 is 2,2'-(((12,13-bis(2-ethylhexyl)-3,9-bisundecyl-12,13-dihydro-[1,2,5]thiadiazo[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]indol-2,10-diyl)bis(methanediyl))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diyl))dimalonitrile,

[0043] PCBM is [6,6]-phenyl C61 butyrate methyl ester.

[0044] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0045] This invention provides a confined directional growth strategy for 2D perovskites, involving the co-doping of formamidine formate (FAFa) and lead thiocyanate (Pb(SCN)2) in the perovskite photoactive layer. FAFa regulates the perovskite crystallization process, obtaining large-sized, well-oriented grains while leaving grain boundary gaps. Without introducing other halide ions, Pb(SCN)2 is used for preliminary passivation of the grain boundaries. During film formation, SCN... - After release, lead iodide (PbI2) forms at the grain boundaries, completing initial passivation. Then, at the grain boundaries, guanidinoiodine (GAI) post-treatment interacts with the PbI2 to obtain a confined, directionally grown 2D perovskite phase. This strategy can also elevate the positions of the conduction band bottom and valence band top of the perovskite, while simultaneously raising the Fermi level, promoting electron transport at the i / n interface, and enhancing hole blocking. This invention provides a new approach to crystallization regulation and grain boundary passivation in perovskite solar cells, offering a broad prospect for further improving the performance of perovskite solar cells and perovskite / organic tandem solar cells.

[0046] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of a perovskite single-junction solar cell structure based on confined directional growth of 2D perovskite, provided by the present invention.

[0049] Figure 2 These are scanning electron microscope (SEM) images of perovskite films before and after modification under different conditions in the embodiments of the present invention.

[0050] Figure 3 The normalized X-ray diffraction (XRD) spectra of perovskite films before and after modification under different conditions in the embodiments of the present invention, and the peak intensity ratio of the perovskite (100) plane to lead iodide.

[0051] Figure 4 The images show grazing incidence wide-angle X-ray scattering (GIWAXS) spectra of perovskite films before and after modification under different conditions in the embodiments of the present invention.

[0052] Figure 5 The images show the photoluminescence (PL) and time-resolved fluorescence (TRPL) spectra of perovskite films before and after modification under different conditions in the embodiments of the present invention.

[0053] Figure 6 The figures show the dark-state current curves of the device before and after modification under different conditions in the embodiments of the present invention.

[0054] Figure 7 The JV curves of perovskite solar cells before and after modification under different conditions are shown in the embodiments of the present invention.

[0055] Figure 8 The JV curves of perovskite / organic tandem solar cells before and after modification under different conditions are shown in the embodiments of the present invention.

[0056] Figure label:

[0057] 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 modified layer; 6. Electron transport layer; 7. Metal electrode. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but cannot be used to limit the scope of this invention.

[0059] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0060] The following is combined with Figures 1 to 8 This invention describes a method for preparing a perovskite photoactive layer based on confined directional growth of 2D perovskite, a solar cell, and the preparation method thereof.

[0061] The perovskite photoactive layer includes a perovskite matrix, formamidine formate (FAFa), lead thiocyanate (Pb(SCN)2), and guanidinoiodine (GAI).

[0062] The grain size of the perovskite matrix is ​​adjusted by FAFa, and gaps are generated at the grain boundaries;

[0063] Initial passivation is performed using (Pb(SCN)2). During the film formation process, SCN... - After release, lead iodide (PbI2) is formed at the grain boundaries.

[0064] GAI was used for post-treatment, reacting with PbI2 at the grain boundaries to achieve confined directional growth of 2D perovskites.

[0065] The molecular structure of formic acid formamidine is: The molecular structure of lead thiocyanate is The molecular structure of guanidino-iodine is .

[0066] A method for preparing a perovskite photoactive layer based on confined directional growth of 2D perovskite, comprising:

[0067] S101: 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 formamidinium hydroiodate (FAI) into 1 ml of a first organic solvent using a precision balance, 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);

[0068] S102: Weigh 0.5-40 mg of FAFa and 0.3-10 mg of Pb(SCN)2 using a precision balance, and dissolve them in 1 ml of perovskite precursor solution until completely dissolved to prepare the preform solution.

[0069] S103: Spin-coat the prepared pre-mixed solution onto the prepared perovskite substrate at a speed of 1000-8000 rpm for 10-60 s, and then perform annealing treatment to form a perovskite photoactive layer.

[0070] S104: Weigh 0.1-10 mg of GAI using a precision balance and dissolve it in 1 ml of a second organic solvent. Heat and stir at 10-80 °C until completely dissolved to prepare a guanidine iodine solution. The second organic solvent includes, but is not limited to, isopropanol (IPA).

[0071] S105: Spin-coat the prepared GAI solution onto the prepared perovskite photoactive layer at a speed of 1000-8000 rpm for 10-60 s, and then anneal it to obtain a perovskite photoactive layer based on 2D perovskite confined directional growth.

[0072] Annealing involves heating to a suitable temperature, holding it at that temperature for a certain time, and then slowly cooling it.

[0073] The annealing process of the perovskite photoactive layer preparation method based on 2D perovskite confined directional growth of the present invention involves heating to 50-150 ℃ and holding at that temperature for 3-30 min.

[0074] The annealing temperature is 50-150 ℃, of which 50 ℃, 100 ℃, and 150 ℃ can be selected.

[0075] The holding time for annealing is 3-30 min, with options including 3 min, 15 min, 25 min, and 30 min.

[0076] 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 sequentially.

[0077] A method for fabricating a perovskite single-junction solar cell based on confined directional growth of 2D perovskite, comprising:

[0078] S201: Ozone treatment is performed on the cleaned transparent conductive substrate 1 ITO glass, followed by spin coating of nickel oxide (NiO) at a speed of 1000-8000 rpm. xSolution 10-60s, anneal at 80-180 ℃ for 5-50 min to obtain hole transport layer 2;

[0079] S202: Spin-coat a solution of [2-(9H-carbazole-9-yl)ethyl]phosphoric acid (2PACz) onto hole transport layer 2 at a speed of 1000-8000 rpm for 10-60 s, and anneal at 50-180 ℃ for 5-50 min to obtain a self-assembled monolayer 3.

[0080] S203: A perovskite photoactive layer 4 based on 2D perovskite confined directional growth is formed on the self-assembled monolayer 3;

[0081] S204: Phenethyl iodide ammonium (PEAI) solution was spin-coated onto the perovskite photoactive layer 4 based on 2D perovskite confined directional growth at a speed of 1000-8000 rpm for 10-60 s, and then annealed at 50-180 ℃ for 5-50 min to obtain PEAI modified layer 5.

[0082] S205: Spin-coat a methyl phenyl C-61 butyrate (PCBM) solution onto the PEAI modified layer 5 at a speed of 1000-8000 rpm for 10-60 s to obtain the electron transport layer 6.

[0083] S206: Spin-coat the supernatant of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) onto electron transport layer 6 at a speed of 1000-8000 rpm for 10-60 s.

[0084] S207: Evaporate Ag electrode 50-150 nm onto the above BCP layer under vacuum conditions to obtain metal electrode 7.

[0085] After steps S201 to S207, a perovskite single-junction solar cell based on 2D perovskite confined directional growth is obtained.

[0086] A perovskite / organic tandem solar cell fabricated based on a confined directional growth strategy of 2D perovskite comprises a transparent conductive substrate, a hole transport layer, a self-assembled monolayer, a perovskite photoactive layer, a PEAI modified layer, an electron transport layer, an Ag / Au interconnect layer, a hole transport layer, a PM6:Y6:PCBM ternary heterojunction layer, an electron transport layer, and an Ag metal electrode stacked sequentially.

[0087] A method for fabricating a perovskite / organic tandem solar cell based on a confined directional growth strategy of 2D perovskite, comprising:

[0088] S301: Ozone treatment is performed on the cleaned transparent conductive substrate ITO glass, followed by spin coating of nickel oxide (NiO) at a speed of 1000-8000 rpm.x The solution is annealed at 80-180 ℃ for 5-50 min after 10-60 s in the solution to obtain the hole transport layer.

[0089] S302: Spin-coat the 2PACz solution onto the hole transport layer at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180℃ for 5-50 min to obtain a self-assembled monolayer.

[0090] S303: Coated onto a self-assembled monolayer to form a perovskite photoactive layer based on 2D perovskite confined directional growth;

[0091] S304: Phenethyl iodide ammonium (PEAI) solution is spin-coated onto a perovskite photoactive layer based on 2D perovskite confined directional growth at a speed of 1000-8000 rpm for 10-60 s, followed by annealing at 50-180 ℃ for 5-50 min to obtain a PEAI modified layer.

[0092] S305: Spin-coat a methyl phenyl C-61 butyrate (PCBM) solution onto the PEAI modified layer at a speed of 1000-8000 rpm for 10-60 s to obtain an electron transport layer;

[0093] S306: Spin-coat the supernatant of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) onto the electron transport layer at a speed of 1000-8000 rpm; spin-coat for 10-60 s.

[0094] S307: An Ag / Au interconnect layer and a molybdenum trioxide (MoO3) layer are evaporated under vacuum conditions to obtain an Ag / Au interconnect layer;

[0095] S308: Spin-coat the above MoO3 layer with a ternary PM6:Y6:PCBM organic solution at a speed of 1000-8000 rpm for 20-80s, and anneal at 50-180 ℃ for 5-50 min to obtain a PM6:Y6:PCBM ternary heterojunction layer.

[0096] S309: Spin-coat the PFN-Br solution onto the PM6:Y6:PCBM ternary heterojunction layer at a speed of 1000-8000 rpm for 10-60s;

[0097] S310: An Ag metal electrode is obtained by evaporating an Ag electrode 50-150 nm onto a PFN-Br layer under vacuum conditions;

[0098] After steps S301 to S310, a perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite is obtained.

[0099] 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],

[0100] Y6 is 2,2'-(((12,13-bis(2-ethylhexyl)-3,9-bisundecyl-12,13-dihydro-[1,2,5]thiadiazo[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]indol-2,10-diyl)bis(methanediyl))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diyl))dimalonitrile,

[0101] PCBM is [6,6]-phenyl C61 butyrate methyl ester.

[0102] Example:

[0103] The C=O in the FAFa additive of this invention can react with Pb 2+ The interaction of ions hinders the formation of large iodopide colloids, contributing to the final acquisition of large-sized perovskite grains while leaving grain boundary gaps. Pb(SCN)₂ additives can effectively fill the gaps between large grains. - During thin film formation, the gas is released as a gas and does not embed itself in the perovskite lattice, leaving PbI2 at the grain boundaries as initial passivation. GAI can interact with the PbI2 at the grain boundaries, ultimately generating a confined, directionally grown 2D perovskite phase, achieving efficient passivation of grain boundary defects while maintaining good electrical performance. This invention achieves confined, directional growth of 2D perovskite using a sequential optimization method, resulting in a significant improvement in both the optical and electrical performance of solar cells.

[0104] The thin film preparation steps of this invention are as follows: Weigh 30 mg of FAFa using a precision balance and place it in vial No. 1. Weigh 30 mg of FAFa and 4.8 mg of Pb(SCN)2 and place them in vial No. 2. Next, add 1 mL of fully dissolved perovskite precursor solution to each vial and stir at room temperature until completely dissolved to obtain a clear and transparent yellow solution. Weigh 2.9 mg of GAI using a precision balance and place it in vial No. 3. Add 1 mL of IPA to the vial and stir at 50°C until completely dissolved to obtain a clear and transparent colorless solution. Thin films without any optimization are labeled as control; thin films containing only FAFa additive are labeled as FAFa; thin films containing both FAFa and Pb(SCN)2 additives are labeled as FAFa&Pb(SCN)2; and thin films containing both FAFa and Pb(SCN)2 additives and using GAI passivating agent are labeled as FAFa&Pb(SCN)2+GAI.

[0105] The device fabrication steps of this invention are as follows: Weigh 2.4 mg of FAFa and 0.8 mg of Pb(SCN)2 using a precision balance, place them in a vial, add 1 mL of fully dissolved perovskite precursor solution to the vial, and stir at room temperature until completely dissolved to obtain a clear and transparent yellow solution. Weigh 1 mg of GAI using a precision balance, place it in a vial, add 2 mL of IPA to the vial, and stir at 50°C until completely dissolved to obtain a clear and transparent colorless solution. Devices without any optimization are labeled as control, and devices containing both FAFa and Pb(SCN)2 additives and using GAI passivating agent are labeled as FAFa&Pb(SCN)2+GAI.

[0106] FAFa additives can alter the grain size of perovskite. To investigate the effect of FAFa treatment on the perovskite crystallization process, this invention performed SEM tests on perovskite films with added FAFa, such as... Figure 2 As shown in (a), the perovskite film without FAFa solution treatment has very small grains, such as Figure 2 (b) and Figure 2 As shown in (e), after adding FAFa, the perovskite grains significantly increased in size, and gaps appeared at the grain boundaries, such as... Figure 3 The XRD pattern shown in (a) indicates that after adding FAFa, the perovskite exhibits (100) plane orientation crystallization.

[0107] like Figure 2 As shown in (c), the FAFa & Pb(SCN)2 dual additives can alter the grain size of perovskite while initially filling grain boundary gaps. Adding Pb(SCN)2 can effectively fill grain boundary cracks. Figure 3(b) shows the XRD pattern, where the PbI2 peak intensity in the perovskite film is enhanced after the addition of Pb(SCN)2. Figure 4 As shown in (b), q z ≈ 0.92 Å −1 The signal at the point corresponds to the (001) plane of PbI2, indicating the formation of PbI2 at the grain boundary.

[0108] GAI solution can react with PbI2 at the aforementioned grain boundaries to achieve confined directional growth of the 2D perovskite phase, such as... Figure 2 As shown in (d), a new phase appeared at the grain boundaries of the perovskite after GAI solution treatment, such as Figure 4 As shown in (a)(c), after treatment with GAI solution, at q z ≈ 0.79 Å −1 Diffraction rings of the 2D perovskite phase appeared, with diffraction intensities concentrated at azimuth angles of 30.14° and 69.97°, indicating that the 2D perovskite phase tends to grow at azimuth angles of 59.86° and 20.03° to the substrate. This completes the confined directional growth of the 2D perovskite.

[0109] The confined directional growth strategy of FAFa & Pb(SCN)2+GAI 2D perovskite can reduce nonradiative recombination and extend carrier lifetime. This invention conducted fluorescence (PL) and time-resolved fluorescence spectroscopy tests on perovskite films with and without a synergistic optimization strategy. The tested structure was a glass / perovskite. Figure 5 The peak position of PL before and after optimization showed no significant change, indicating that the additive was not embedded in the perovskite structure. After optimization, the PL peak intensity was significantly enhanced, and the carrier lifetime obtained by fitting the corresponding TRPL was also significantly extended. The increased perovskite grain size after optimization reduced grain boundaries in films of the same area, and nonradiative recombination of carriers and ion migration are most likely to occur at grain boundaries. This optimization strategy effectively passivates grain boundaries while reducing them, which is beneficial for the efficient transport of photogenerated carriers.

[0110] The confined, directional growth strategy of FAFa & Pb(SCN)2+GAI 2D perovskite can reduce the dark-state leakage current of solar cells. This invention conducted dark-state JV tests on perovskite solar cells with and without a synergistic optimization strategy. Figure 6 The optimized device shows a significant reduction in dark-state current, indicating a decrease in defect states, consistent with SEM and PL results. The confined directional growth strategy of 2D perovskites can optimize the performance of perovskite solar cell devices. This invention uses a one-step anti-solvent method to fabricate a perovskite single-junction solar cell with a device structure of ITO / NiOx / 2PACz / perovskite photoactive layer / PEAI / PCBM / BCP / Ag. Under sunlight irradiation (AM1.5G, 100 mW / cm²), the device... 2The effective area is 0.08875 cm². 2 Perovskite solar cells. Table 1 shows the key photovoltaic parameters of perovskite single-junction solar cells before and after optimization;

[0111] Table 1 Key photovoltaic parameters of perovskite single-junction solar cells before and after optimization

[0112]

[0113] Ultimately, an efficiency of 18.06% and a current of 17.16 mA / cm² were achieved. 2 The current density, open-circuit voltage of 1283 mV, and fill factor of 81.97% are shown. Figure 7 As shown, the confined directional growth strategy of 2D perovskites can significantly improve the performance of devices.

[0114] The confined directional growth strategy for 2D perovskites is also applicable to perovskite / organic tandem solar cells. Table 2 shows the key photovoltaic parameters of perovskite / organic tandem solar cells before and after optimization of the 2D perovskite confined directional growth strategy.

[0115] Table 2 Key photovoltaic parameters of perovskite / organic tandem solar cells before and after optimization

[0116]

[0117] like Figure 8 As shown, the tandem solar cell optimized by the confined directional growth strategy of 2D perovskite achieved an efficiency of 22.41% and a fill factor of 75.54.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate 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 confined directional growth of 2D perovskite, characterized in that, include: S101: Weigh 0.1-0.3 mg lead iodide, 0.1-0.3 mg lead bromide, 0.02-0.3 mg cesium iodide, and 0.05-0.3 mg formamidin hydroiodate into 1 ml of the first organic solvent using a precision balance, and stir until completely dissolved to prepare a perovskite precursor solution; S102: Weigh 0.5-40 mg of formamidinium formate and 0.3-10 mg of lead thiocyanate using a precision balance, and dissolve them in 1 ml of perovskite precursor solution until completely dissolved to prepare the preform solution. S103: Spin-coat the prepared pre-mixed solution onto the prepared perovskite substrate at a speed of 1000-8000 rpm for 10-60 s, and then perform annealing treatment to form a perovskite photoactive layer. S104: Weigh 0.1-10 mg of guanidinoiodine using a precision balance and dissolve it in 1 ml of a second organic solvent. Heat and stir at 10-80 °C until completely dissolved to prepare a guanidinoiodine solution. S105: Spin-coat the prepared guanidino-iodine solution onto the prepared perovskite photoactive layer at a speed of 1000-8000 rpm for 10-60 s, and then perform annealing treatment to obtain a perovskite photoactive layer based on 2D perovskite confined directional growth.

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

3. The method for preparing a perovskite photoactive layer based on confined directional growth of 2D perovskite 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 confined directional growth of 2D perovskite or a perovskite / organic tandem solar cell based on confined directional growth of 2D perovskite, and the solar cell includes the perovskite photoactive layer based on confined directional growth of 2D perovskite as described in any one of claims 1 to 3.

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

6. The solar cell according to claim 5, characterized in that, The fabrication method of perovskite single-junction solar cells based on confined directional growth of 2D perovskite is as follows: S201: Ozone treatment is performed on the cleaned transparent conductive substrate ITO glass, and nickel oxide solution is spin-coated at a speed of 1000-8000 rpm for 10-60s, followed by annealing at 80-180 ℃ for 5-50 min to obtain the hole transport layer. S202: Spin-coat a solution of [2-(9H-carbazole-9-yl)ethyl]phosphoric acid onto the hole transport layer at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180 ℃ for 5-50 min to obtain a self-assembled monolayer. S203: A perovskite photoactive layer formed on a self-assembled monolayer based on 2D perovskite confined directional growth; S204: Spin-coat a phenylethyl ammonium iodide solution onto a perovskite photoactive layer based on 2D perovskite confined directional growth at a speed of 1000-8000 rpm for 10-60s, and anneal at 50-180 ℃ for 5-50 min to obtain a PEAI modified layer. S205: A methyl phenyl C-61 butyrate solution is spin-coated onto the PEAI modified layer at a speed of 1000-8000 rpm for 10-60 s to obtain an electron transport layer; S206: Spin-coat the supernatant of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline onto the electron transport layer at a speed of 1000-8000 rpm for 10-60s; S207: Evaporate an Ag electrode 50-150 nm into 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 the confined directional growth of 2D perovskite is prepared.

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

8. The solar cell according to claim 7, characterized in that, The fabrication method of perovskite / organic tandem solar cells based on confined directional growth of 2D perovskite is as follows: S301: Ozone treatment is performed on the cleaned transparent conductive substrate ITO glass, and nickel oxide solution is spin-coated at a speed of 1000-8000 rpm, followed by annealing at 80-180 ℃ for 5-50 min; a hole transport layer is obtained. S302: Spin-coat a solution of [2-(9H-carbazole-9-yl)ethyl]phosphoric acid onto the hole transport layer at a speed of 1000-8000 rpm, and anneal at 50-180 ℃ for 5-50 min to obtain a self-assembled monolayer. S303: A perovskite photoactive layer formed on a self-assembled monolayer based on 2D perovskite confined directional growth; S304: Spin-coat a phenylethylamine iodide solution onto a perovskite photoactive layer based on 2D perovskite confined directional growth at a speed of 1000-8000 rpm, and anneal at 50-180 ℃ for 5-50 min to obtain a PEAI modified layer. S305: A methyl phenyl C-61 butyrate solution was spin-coated onto the PEAI modified layer at a speed of 1000-8000 rpm to obtain an electron transport layer; S306: Spin-coat the supernatant of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline onto the electron transport layer at a speed of 1000-8000 rpm; S307: An Ag / Au interconnect layer and a molybdenum trioxide layer are evaporated under vacuum conditions to obtain an Ag / Au interconnect layer; S308: Spin-coat a ternary PM6:Y6:PCBM organic solution onto a molybdenum trioxide layer at a speed of 1000-8000 rpm for 20-80s, and anneal at 50-180 ℃ for 5-50 min to obtain a PM6:Y6:PCBM ternary heterojunction layer. S309: Spin-coat a solution of poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide onto a PM6:Y6:PCBM ternary heterojunction layer at a speed of 1000-8000 rpm for 10-60 seconds; S310: An Ag metal electrode is obtained by evaporating an Ag electrode 50-150 nm onto a poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide layer under vacuum conditions; Steps S301 to S310 are followed to prepare perovskite / organic tandem solar cells based on confined directional growth of 2D perovskite. 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-bisundecyl-12,13-dihydro-[1,2,5]thiadiazo[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]indol-2,10-diyl)bis(methanediyl))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diyl))dimalonitrile, PCBM is [6,6]-phenyl C61 butyrate methyl ester.

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