Perovskite solar cell and preparation method thereof, optoelectronic device

Abstract

This application provides a perovskite solar cell and its fabrication method, relating to the field of solar cell technology. The perovskite solar cell of this application includes a perovskite light-absorbing layer, which comprises a three-dimensional perovskite film and a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film. The two-dimensional perovskite and the three-dimensional perovskite film constitute a heterojunction structure, and the two-dimensional perovskite is either an ACI two-dimensional perovskite or a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite. The formation of the ACI two-dimensional phase facilitates the suppression of nonradiative recombination on the perovskite film surface and in the bulk phase, reduces the work function of the perovskite surface, forms a slightly n-biased perovskite surface, and obtains a more matched energy level arrangement of the perovskite / electron transport layer. Ultimately, the performance of the wide-bandgap perovskite solar cell based on the two-dimensional / three-dimensional perovskite heterojunction is significantly improved.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, specifically to a perovskite solar cell and its fabrication method, as well as an optoelectronic device. Background Technology

[0002] In recent years, the technology of two-terminal tandem solar cells based on silicon and wide-bandgap perovskite has developed rapidly, with the world's highest certified efficiency reaching 32.5%. Among them, the non-radiative recombination of the wide-bandgap perovskite bulk phase and surface leads to a large open-circuit voltage loss and poor interfacial charge transport, which is one of the main factors limiting the development of tandem solar cells.

[0003] Two-dimensional perovskites are a class of layered semiconductor materials whose inorganic framework is separated by organic molecular layers, exhibiting two-dimensional layered characteristics and relatively high quantum efficiency. The construction of two-dimensional / three-dimensional perovskite heterojunctions is beneficial for interface defect passivation and better energy level alignment, and can be applied to improve device performance. However, it has been found that the introduction of two-dimensional perovskites (such as the commonly used Ruddlesden-Popper, RP two-dimensional perovskite) increases the open-circuit voltage (V0) of the device. OC However, this will also lead to a decrease in the fill factor (FF). Summary of the Invention

[0004] This application aims to provide a perovskite solar cell and its fabrication method, as well as an optoelectronic device, which can construct two-dimensional / three-dimensional perovskite heterojunctions on the surface of the light-absorbing layer to suppress non-radiative recombination of perovskite, while also improving carrier transport at the interface between perovskite and transport layer, thereby realizing a high-performance perovskite solar cell.

[0005] In a first aspect, embodiments of this application provide a perovskite solar cell, including a perovskite light-absorbing layer, the perovskite light-absorbing layer comprising: a three-dimensional perovskite film layer, and a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film layer; wherein the two-dimensional perovskite and the three-dimensional perovskite film layer constitute a heterojunction structure, and the two-dimensional perovskite is: Alternating Cations in the Inter-layer Space (ACI) two-dimensional perovskite, or a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite.

[0006] Optionally, the miscible two-dimensional perovskite containing ACI two-dimensional perovskite includes: a miscible two-dimensional perovskite containing a mixture of ACI two-dimensional perovskite and RP two-dimensional perovskite.

[0007] Optionally, the spacer cations of the ACI two-dimensional perovskite are alternating guanidine ions and a first cation, wherein the first cation is the same as the A-site cation of the three-dimensional perovskite film.

[0008] Optionally, the perovskite solar cell further includes a C60 electron transport layer formed on a two-dimensional perovskite.

[0009] Secondly, embodiments of this application provide a multi-junction tandem solar cell including a perovskite sub-cell, wherein the perovskite sub-cell is any of the perovskite solar cells described above.

[0010] Thirdly, embodiments of this application also provide a method for preparing a perovskite solar cell, including a step of preparing a perovskite light-absorbing layer. The step of preparing the perovskite light-absorbing layer includes: preparing a three-dimensional perovskite film; coating the three-dimensional perovskite film with a treatment liquid, the treatment liquid including at least a first material for generating ACI two-dimensional perovskite; and annealing to generate two-dimensional perovskite at the upper interface of the three-dimensional perovskite film, the two-dimensional perovskite including ACI two-dimensional perovskite, or a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite.

[0011] Optionally, the first material used to generate ACI two-dimensional perovskite includes: guanidine halide or guanidine salt.

[0012] Preferably, the treatment solution has a concentration of 1.5 mg / mL. –1 ~2.5mg mL –1 A solution of guanidine chloride (GACl) in isopropanol (IPA); more preferably, the treatment solution has a concentration of 2 mg / mL. –1 A solution of guanidine chloride (GACl) in isopropanol (IPA).

[0013] Optionally, the treatment solution further includes a second material for generating RP two-dimensional perovskite; the two-dimensional perovskite generated after annealing is a mixed-phase two-dimensional perovskite consisting of ACI two-dimensional perovskite and RP two-dimensional perovskite.

[0014] Optionally, the treatment solution includes a mixed solution of GACl and oleamine iodine (OAmI).

[0015] Preferably, the mass concentration ratio of GACl to OAmI is 1.5:0.4 to 2.5:0.4; more preferably, the molar concentration ratio of GACl to OAmI is 2:0.4.

[0016] Optionally, the process of generating a two-dimensional perovskite at the upper interface of the three-dimensional perovskite film includes: coating the treatment solution onto the surface of the three-dimensional perovskite film in a first time to avoid the formation of yellow phase perovskite; annealing immediately after coating and cooling to generate a two-dimensional perovskite on the surface of the three-dimensional perovskite film.

[0017] Optionally, a mixed IPA solution of GACl and OAmI is dropped onto the three-dimensional perovskite film and immediately spin-coated, wherein the time from the first contact between the mixed IPA solution of guanidine chloride and oleamide iodine and the second time of coating begins does not exceed 3 seconds.

[0018] Fourthly, embodiments of this application also provide an optoelectronic device including a perovskite film layer. The perovskite film layer optoelectronic device includes a perovskite functional layer, which includes: a three-dimensional perovskite film layer; and a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film layer, wherein the two-dimensional perovskite is: ACI two-dimensional perovskite, or a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite.

[0019] The perovskite solar cell provided in this application further includes a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film layer. The two-dimensional perovskite includes ACI two-dimensional perovskite or a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite. The interface of the three-dimensional perovskite is processed to generate ACI two-dimensional perovskite, or to generate a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite, resulting in a slightly n-type perovskite surface. This forms a heterojunction structure of two-dimensional perovskite / three-dimensional perovskite on the upper layer of the perovskite light-absorbing layer, which greatly improves carrier transport at the interface between the perovskite and the transport layer. Simultaneously, the ACI two-dimensional perovskite can suppress non-radiative recombination of the perovskite, significantly improving the photoelectric efficiency of the perovskite solar cell.

[0020] Furthermore, the perovskite solar cell fabrication method provided in this application can also post-treat the three-dimensional perovskite film using a processing solution to generate in-situ mixed-phase alternating cation ACI two-dimensional perovskite and RP two-dimensional perovskite on the perovskite surface. This mixed-phase two-dimensional perovskite can significantly improve the perovskite carrier lifetime, obtain a slightly n-type perovskite surface, and achieve better perovskite / transport layer energy level alignment, thereby greatly improving the photoelectric efficiency of the perovskite solar cell.

[0021] In this application embodiment, an IPA solution of GACl and OAmI can also be used to post-process the three-dimensional perovskite film, resulting in a perovskite light-absorbing layer with a mixed-phase two-dimensional / three-dimensional heterojunction. The technical solution of this application has the following advantages: the formation of the mixed-phase two-dimensional perovskite can passivate defects on the perovskite surface, and the guanidine ion GACl... + Because of their small size, these perovskites can partially penetrate into the interior of perovskite films, significantly improving carrier lifetime at the perovskite film surface and in the bulk phase, and suppressing nonradiative recombination. The formation of mixed-phase two-dimensional perovskites makes the surface of three-dimensional perovskites more n-type, thus better matching the energy levels of the perovskite with the electron transport layer and promoting carrier transport at the interface. A 1cm [structure / project / structure] based on a mixed-phase two-dimensional / three-dimensional perovskite heterojunction... 2The device boasts a maximum photoelectric conversion efficiency of 21.65%, of which V OC The voltage is 1.225V, the FF is 85.58%, and the short-circuit current density (J) is... SC The value is 20.64 mA·cm. –2 . Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the perovskite light-absorbing layer of the perovskite solar cell provided in the embodiments of this application;

[0023] Figure 2 This is a flowchart of the fabrication method of perovskite solar cells provided in the embodiments of this application;

[0024] Figure 3 This is a schematic diagram comparing the powder X-ray diffraction (XRD) of the three-dimensional perovskite film without treatment solution provided in Experimental Example 1 of this application and the ACI two-dimensional / three-dimensional perovskite heterojunction films obtained by treatment with GACl / IPA solutions of different concentrations.

[0025] Figure 4 These are morphological comparison images of the untreated three-dimensional perovskite film provided in Experimental Example 1 of this application and the two-dimensional / three-dimensional perovskite heterojunction film obtained by treatment with GACl / IPA solution;

[0026] Figures 5(a) to 5(d) Box plots of electrical tests for three experimental sample samples with GACl treatment solution concentrations of 1.5 mg / mL, 2 mg / mL, and 2.5 mg / mL, respectively, provided in Experimental Example 1 of this application;

[0027] Figures 6(a) to 6(d) Box plots of electrical tests for untreated three-dimensional perovskites provided in Experimental Examples 1 and 2 of this application, and for three experimental sample samples treated with 2 mg / mL GACl / IPA solution and GACl / OAmI mixed IPA solution.

[0028] Figure 7 The device based on the two-dimensional / three-dimensional perovskite heterojunction thin film obtained by GACl / OAmI processing provided in Experimental Example 2 of this application (light-collecting area 1 cm²) 2 Performance test result curve;

[0029] Figure 8 The morphology comparison diagrams are provided for the untreated three-dimensional perovskite film and the mixed-phase two-dimensional / three-dimensional perovskite heterojunction film obtained by treating with GACl / OAmI in Experimental Example 2 of this application.

[0030] Figure 9These are the grazing incidence X-ray diffraction (GIXRD) patterns of the three-dimensional perovskite thin film and the mixed-phase two-dimensional / three-dimensional perovskite heterojunction thin film provided in Experimental Example 2 of this application;

[0031] Figure 10 These are the time-resolved fluorescence (TRPL) spectra of the untreated three-dimensional perovskite film and the mixed-phase two-dimensional / three-dimensional perovskite heterojunction film obtained by treatment with GACl / OAmI provided in Experimental Example 2 of this application;

[0032] Figure 11 These are surface potential diagrams of the untreated three-dimensional perovskite film and the mixed-phase two-dimensional / three-dimensional perovskite heterojunction film obtained by treating with GACl / OAmI, provided in Experimental Example 2 of this application.

[0033] Figure 12 This is an energy level arrangement diagram of perovskite / C60 in the untreated three-dimensional perovskite film provided in Experimental Example 2 of this application and the mixed-phase two-dimensional / three-dimensional perovskite heterojunction film obtained by treatment with GACl / OAmI. Detailed Implementation

[0034] To facilitate understanding, the terminology used in this article will be briefly explained below.

[0035] Perovskite: The chemical formula of perovskite is ABX3, where: A can be a monovalent organic cation or an inorganic cation, or a mixture of two or more monovalent cations in a certain proportion; B can be a divalent metal ion; X can be I... – ,Br – Cl – Or a mixture of the three in a certain proportion.

[0036] When large organic cations are present in the perovskite composition, a two-dimensional structure can be formed. The thickness of the two-dimensional perovskite is determined by the number (n) of the inorganic framework layers interspersed by large organic cations. The case where n = 1 is defined as purely two-dimensional. When n > 1, two-dimensional perovskites exhibit various types, such as the common Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) types.

[0037] Depending on their crystal structure, two-dimensional perovskites can be classified into two-dimensional or quasi-two-dimensional perovskites, such as the Ruddlesden-Popper (RP) phase, the Dion-Jacobson (DJ) phase, and the ACI phase with alternating cations.

[0038] The structural formula of the RP phase two-dimensional perovskite is A'2A. n–1 M n X 3n+1 Where A' is a monovalent organic spacer cation, and A can be methylamine (CH3NH3).+ MA), formamidin (HC(NH2)2 + Cations such as FA, B can be divalent metal ions such as Pb or Sn, and X can be I. – ,Br – Cl – Isohalogen ions, where n is the number of inorganic framework layers.

[0039] The DJ phase two-dimensional perovskite structure is A'A n–1 B n X 3n+1 Where A' is a divalent interlayer organic cation, A can be a cation such as MA or FA, B can be a divalent metal ion such as Pb or Sn, and X can be I. – ,Br – Cl – Isohalogen ions, where n is the number of inorganic framework layers.

[0040] The structure of the ACI phase two-dimensional perovskite is A'A n B n X 3n+1 Where A' is an alkylammonium cation (mainly a larger guanidine cation), A can be a cation such as MA or FA, B can be a divalent metal ion such as Pb or Sn, and X can be I – ,Br – Cl – Isohalogen ions, where n is the number of inorganic framework layers.

[0041] The following describes the perovskite solar cell with two-dimensional / three-dimensional perovskite heterojunction and its preparation method in conjunction with specific embodiments. The purpose is to enable the public to better understand the technical content, and not to limit it to technical means. In fact, any improvements to this application based on the same or similar principles are within the scope of the technical solutions claimed in this application.

[0042] like Figure 1 As shown, an embodiment of this application provides a perovskite solar cell, including a perovskite light-absorbing layer 10. The perovskite light-absorbing layer 10 includes a three-dimensional perovskite film 11 and a two-dimensional perovskite 12 distributed on the upper interface of the three-dimensional perovskite film 11. The two-dimensional perovskite 12 and the three-dimensional perovskite film 11 form a heterojunction structure, and the two-dimensional perovskite 12 is an ACI two-dimensional perovskite.

[0043] In this application, "upper interface" refers to the interface opposite to the substrate interface of the perovskite thin film (referred to as the buried interface by those skilled in the art).

[0044] In this application, the A-site cations in the ACI two-dimensional perovskite and the A-site cations in the three-dimensional perovskite film can be the same or different. The ACI two-dimensional perovskite can be generated in situ at the upper interface of the three-dimensional perovskite film, in which case the A-site cations in the ACI two-dimensional perovskite can be spontaneously acquired from the three-dimensional perovskite film. Alternatively, the ACI two-dimensional perovskite can be formed at the upper interface of the three-dimensional perovskite film through other preparation methods, in which case the A-site cations in the ACI two-dimensional perovskite and the A-site cations in the three-dimensional perovskite film can be different.

[0045] Preferably, the spacer cations in the ACI two-dimensional perovskite are alternating guanidine ions and a first cation, the first cation being the same as the A-site cation of the three-dimensional perovskite film. The ACI two-dimensional perovskite can be generated in situ at the upper interface by coating a treatment solution onto the three-dimensional perovskite film 11. The treatment solution can be, for example, a solution of guanidine halide or a guanidine salt. The guanidine halide can be exemplarily selected from guanidine bromide or guanidine chloride, and the guanidine salt can be exemplarily selected from guanidine thiocyanate.

[0046] The ACI two-dimensional perovskite is formally called alternating spacer cation-layer perovskite, where the spacer layer can be alternating GA. + And the A-site cation. The ligand size of ACI two-dimensional perovskites is slightly larger than that of the A-site cation (e.g., FA). + It can enter the 3D perovskite lattice, passivate perovskite defects and interface defects, and has good carrier transport capability. It can suppress nonradiative recombination while regulating the energy level and electronic state of the perovskite surface and promoting carrier transport.

[0047] Although guanidine cations are currently reported as the main organic spacer cations capable of forming ACI two-dimensional perovskites, those skilled in the art will understand that the ACI two-dimensional perovskites of this application are not limited to ACI-phase two-dimensional perovskites with guanidine cations as spacer ions. Without affecting the implementation effect of this application, guanidine cations may be replaced with other cations. In other embodiments of this application, the ACI two-dimensional perovskite can also be replaced with a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite, that is, the two-dimensional perovskite 12 can be a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite and other two-dimensional perovskite phases besides the ACI phase. Here, phase mixing refers to the physical mixing and intermingling distribution of ACI two-dimensional perovskite and other two-dimensional perovskites.

[0048] In some embodiments, an ACI two-dimensional perovskite is selected to form a mixed-phase two-dimensional perovskite with another two-dimensional perovskite other than ACI. The ligand size of the ACI two-dimensional perovskite is generally slightly larger than the A-site cation, such as GA. + Slightly larger than FA +It can enter the three-dimensional perovskite lattice (meeting the tolerance factor requirements in perovskite) and has the effect of passivating bulk defects.

[0049] ACI two-dimensional perovskites possess excellent carrier transport capabilities, which can suppress nonradiative recombination while modulating the energy levels and electronic states of the perovskite surface, thus promoting carrier transport. Another type of two-dimensional perovskite, such as the commonly used RP perovskite and DJ perovskite, is used to construct two-dimensional / three-dimensional heterojunctions, primarily to suppress nonradiative recombination on the perovskite surface. RP perovskite is preferred as the alternative. The mixed-phase two-dimensional perovskite formed by blending these two types of two-dimensional perovskites can not only more comprehensively suppress surface nonradiative recombination but also achieve greater modification of the perovskite surface, preparing a more n-type surface and promoting electron transport at the perovskite / electron transport layer (e.g., C60) interface. Furthermore, small-sized ligands, such as GA... + The ligands, not fully involved in the formation of the surface ACI two-dimensional perovskite, are allowed to partially diffuse downwards into the three-dimensional perovskite bulk due to their small size, thus passivating defects. Therefore, the mixed-phase two-dimensional perovskite of this application possesses the advantages of both types of two-dimensional perovskites, and can promote carrier transport while suppressing nonradiative recombination, thereby achieving a significant improvement in device performance.

[0050] Preferably, the two-dimensional perovskite is a mixed-phase two-dimensional perovskite composed of ACI two-dimensional perovskite and RP two-dimensional perovskite. Based on the mixed-phase two-dimensional perovskite formed by ACI two-dimensional perovskite and RP two-dimensional perovskite, a mixed-phase two-dimensional / three-dimensional perovskite heterojunction is formed at the perovskite / electron transport layer interface. Based on this, a 1cm... 2 The device boasts a maximum photoelectric conversion efficiency of 21.65%, with an open-circuit voltage (V0) of [missing information]. OC The voltage is 1.225V, the fill factor (FF) is 85.58%, and the short-circuit current density (J) is... SC The value is 20.64 mA·cm. –2 .

[0051] In other embodiments of this application, the two-dimensional perovskite 12 may also be formed as follows: a portion of the region is ACI two-dimensional perovskite, and a portion of the region is a mixed-phase two-dimensional perovskite formed by mixing ACI two-dimensional perovskite with other two-dimensional perovskites.

[0052] Optionally, the perovskite solar cell further includes a C60 electron transport layer formed on a two-dimensional perovskite.

[0053] The perovskite solar cell may further include other functional layers, such as a bottom electrode and a hole transport layer located on one side (light-incident side) of the perovskite light-absorbing glass substrate; and an electron transport layer and a top electrode located on the other side (backlight side) of the perovskite light-absorbing layer. The bottom electrode can be made of any material suitable for perovskite solar cells, such as ITO, FTO, IWO, ICO, IZO, AZO, or other materials, which are not limited in this application. Furthermore, the bottom electrode may be omitted. The hole transport layer can be made of any hole transport layer material suitable for perovskite solar cells, such as PTAA, PEDOT:PSS, Spiro-OMeTAD, Poly-TPD, CuSCN, Cu2O, CuI, NiO. x The material can be any one of P3HT, MoOx, V2O5, 2PACz, 4PACz, MeO-4PACz, Spiro-TTB, F4-TCNQ, F6-TCNNQ, m-MTDATA, MeO-2PACz, and TAPC, or other hole transport layer materials, which are not limited in this application; the material of the three-dimensional perovskite film has the chemical formula ABX3, and can be any perovskite light-absorbing layer material suitable for perovskite solar cells, such as iodine-based perovskite materials such as FAPbI3, MAPbI3, and FACsPbI3, as well as mixed cationic and anionic perovskite materials, such as FACsPbIBrCl, FAMACsPbIBrCl, FACsDMAPbIBrCl, CsDMAPbIBrCl, FACsPbIBr, FAMACsPbSnIbIBr, FACsDMAPbIBr, and CsDMAPbIBr, which are not limited in this application. The electron transport layer material can be any material suitable for electron transport layers in perovskite solar cells, such as at least one of PCBM, TiO2, ZnO, SnO2, H-PDI, F-PDI, C60, and ICBA, or other electron transport layer materials, which are not limited in this application; the top electrode material can be any existing top electrode material suitable for perovskite solar cells, such as at least one of Ag, Au, Cu, C, Al, ITO, FTO, IWO, ICO, IZO, and AZO, or other top electrode materials, which are not limited in this application.

[0054] Furthermore, perovskite solar cells may also include other functional layers, such as electron blocking layers and hole blocking layers. For example, when a perovskite solar cell is provided with a hole transport blocking layer, the hole blocking layer is disposed between the electron transport layer and the top electrode. The material of the hole blocking layer can be any existing hole blocking layer material suitable for perovskite solar cells, such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) or SnO2, or it can be other hole blocking layer materials or materials without a blocking layer, which are not limited in this application.

[0055] The aforementioned functional membrane layers do not affect the implementation effect of the solution in this application, therefore this application does not limit them, and the above description is only an example.

[0056] This application uses a mixed IPA solution of GACl and OAmI to post-treat wide-bandgap perovskite films, generating an in-situ hybrid phase of ACI two-dimensional perovskite and RP two-dimensional perovskite on the perovskite surface. This hybrid two-dimensional perovskite can significantly improve the carrier lifetime of the perovskite, resulting in a slightly n-type perovskite surface and better perovskite / C60 energy level alignment, greatly improving the photoelectric efficiency of perovskite solar cells. Here, C60 represents a commonly used electron transport layer material in perovskite solar cells.

[0057] Secondly, embodiments of this application provide a multi-junction tandem solar cell including a perovskite sub-cell, wherein the perovskite sub-cell is any of the perovskite solar cells described above. Exemplarily, the multi-junction tandem solar cell of this application can be a crystalline silicon / perovskite tandem cell.

[0058] In the embodiments of this application, the perovskite sub-cell has an ACI two-dimensional perovskite on the upper interface of its perovskite light-absorbing layer, or a mixed-phase two-dimensional perovskite with ACI two-dimensional perovskite and other two-dimensional perovskites besides ACI. The perovskite light-absorbing main film layer (i.e., three-dimensional perovskite) is modified by the two-dimensional perovskite on the upper interface to obtain a slightly n-type perovskite surface. This three-dimensional perovskite light-absorbing layer forms a heterojunction structure of two-dimensional / three-dimensional perovskite, which can improve carrier transport at the interface between perovskite and transport layer, while suppressing nonradiative recombination of perovskite, greatly improving the photoelectric efficiency of single-junction solar cells and multi-junction tandem solar cells.

[0059] Optionally, the two-dimensional perovskite is a mixed-phase two-dimensional perovskite consisting of ACI two-dimensional perovskite and RP two-dimensional perovskite or DJ two-dimensional perovskite, preferably a mixed-phase two-dimensional perovskite consisting of ACI two-dimensional perovskite and RP two-dimensional perovskite.

[0060] Optionally, the spacer cations of the ACI two-dimensional perovskite are alternating guanidine ions and formamidin ions.

[0061] Optionally, the perovskite solar cell further includes a C60 electron transport layer formed on a two-dimensional perovskite.

[0062] On the other hand, embodiments of this application also provide a method for fabricating a perovskite solar cell, including a step of fabricating a perovskite light-absorbing layer, such as... Figure 2 As shown, the fabrication process of the perovskite light-absorbing layer includes:

[0063] S101, Preparation of three-dimensional perovskite film;

[0064] S102. Coating a treatment liquid onto a three-dimensional perovskite film, the treatment liquid comprising at least a first material for generating ACI two-dimensional perovskite;

[0065] S103. Annealing is performed to generate a two-dimensional perovskite at the upper interface of the three-dimensional perovskite film. The two-dimensional perovskite includes ACI two-dimensional perovskite, or the two-dimensional perovskite includes a miscible two-dimensional perovskite containing ACI two-dimensional perovskite.

[0066] The perovskite light-absorbing layer preparation process of this application involves first generating a three-dimensional perovskite film using relevant techniques (e.g., a one-step solution method or a two-step solution method), then coating the upper interface of the three-dimensional perovskite film with a treatment solution, followed by annealing, to generate a two-dimensional perovskite in situ on the upper interface of the three-dimensional perovskite film. The generated two-dimensional perovskite has a very small thickness, generally in the nm range, not exceeding 30 nm, and can partially or completely cover the three-dimensional perovskite film. For example, the thickness of the two-dimensional perovskite layer is less than 20 nm, such as approximately a few nanometers to tens of nanometers.

[0067] Three-dimensional perovskite films can be, for example, wide-bandgap perovskites with a bandgap greater than 1.6 eV, with the chemical formula ABX3, where: A can be a monovalent organic or inorganic cation; B can be a divalent metal ion; and X can be I. – ,Br – Cl – Three-dimensional perovskite films can also be perovskites with a voltage below 1.6 eV.

[0068] In addition to the fabrication process of the perovskite light-absorbing layer, the fabrication method of the perovskite solar cell of this application also includes the process of fabricating other functional films. These other functional films may include, for example, a bottom electrode and a hole transport layer located on the light-incident side of the perovskite light-absorbing layer, and an electron transport layer and a top electrode located on the light-incident side of the perovskite backlight layer. They may further include a hole-blocking layer, an electron-blocking layer, and an interface modification layer, etc. These functional films do not affect the implementation effect of the solution of this application; therefore, the fabrication processes of these films will not be described in detail in this application.

[0069] In some embodiments, the first material in the treatment solution used to generate ACI two-dimensional perovskite may include: guanidine halide or guanidine salt, for example, the treatment solution having a guanidine ion concentration of 1.5 mg·mL⁻¹. –1 ~2.5 mg·mL –1 The solution, preferably, the treatment solution can be a solution with a concentration of 2 mg·mL⁻¹ –1 GACl in IPA solution.

[0070] In other embodiments, the processing solution may further include a second material for generating RP two-dimensional perovskite; correspondingly, the two-dimensional perovskite generated after annealing in step S103 is a mixed-phase two-dimensional perovskite containing both ACI and RP two-dimensional perovskite. For example, the processing solution may include a mixed solution of GACl and OAmI; wherein the mass concentration ratio of guanidine chloride to oleamide iodine is (1.5:0.4) to (2.5:0.4). For example, the mass concentration ratio of GACl to OAmI can be 1.5:0.4, 1.7:0.4, 1.9:0.4, 2:0.4, 2.2:0.4, or 2.5:0.4. Preferably, the mass concentration ratio of GACl to OAmI is 2:0.4.

[0071] In some embodiments, the second material used to generate the RP two-dimensional perovskite in the treatment solution may be at least one of oleylamine iodine, phenethylamine iodine, and butylamine iodine; exemplaryly, the treatment solution may be any one of a mixed solution of guanidine bromide and oleylamine iodine, a mixed solution of guanidine chloride and phenethylamine iodine, a mixed solution of guanidine chloride and butylamine iodine, or a mixed solution of guanidine chloride and tetraoctylammonium bromide.

[0072] In other embodiments, the processing solution may also include materials for generating the DJ two-dimensional perovskite phase, i.e., the processing solution is a mixed solution including materials that can form ACI two-dimensional perovskites and materials that can form DJ two-dimensional perovskites, such as a mixed solution of guanidine chloride and ethylenediamine.

[0073] In this application, after the processing solution contacts the surface of the three-dimensional perovskite film, the processing solution needs to coat the surface of the three-dimensional perovskite film within a certain time, that is, the processing solution coats the surface of the three-dimensional perovskite film within the first time. Here, the length of the first time can be adjusted according to different film formation processes. Its length should not be too long or too short. If the first time is too short, the cations in the processing solution may not have enough time to react with the three-dimensional perovskite. If the first time is too long, guanidine ions may excessively penetrate into the three-dimensional perovskite film, resulting in the formation of yellow-phase perovskite without photoelectric effect. For example, the first time does not exceed 5 seconds; wherein, the start and end points of the first time are: from the time the processing solution contacts the surface of the three-dimensional perovskite film to the time of coating.

[0074] The film-forming process used in this application can be a conventional film-forming process in the field of optoelectronic devices, such as spraying, slot coating, spin coating, etc.

[0075] In some embodiments, the coating of the treatment liquid onto the three-dimensional perovskite film in step S102 may include: immediately rotating the substrate after dropping the treatment liquid comprising the first material onto the surface of the three-dimensional perovskite film, such that the time from the first moment when the precursor liquid contacts the surface of the three-dimensional perovskite film to the second moment when the substrate begins to rotate does not exceed 3 seconds. Annealing is performed immediately after coating, and after cooling, an ACI two-dimensional perovskite is generated on the surface of the three-dimensional perovskite film. See Experiment 1 appended at the end of this application; using this method, an ACI two-dimensional perovskite can be generated on the surface of the three-dimensional perovskite film, forming an ACI two-dimensional perovskite / three-dimensional perovskite heterojunction.

[0076] Optionally, the coating of the treatment solution onto the three-dimensional perovskite film in step S102 may include: dropping a mixed IPA solution of GACl and OAmI onto the three-dimensional perovskite film and immediately spin-coating it, followed by step S103: annealing to obtain a mixed-phase two-dimensional / three-dimensional heterojunction perovskite film; wherein the time from the first contact between the mixed IPA solution of GACl and OAmI and the surface of the three-dimensional perovskite film to the second time when the substrate begins to rotate does not exceed 3 seconds. See Experiment 2 appended to the end of this application. Using this method, a mixed-phase two-dimensional perovskite containing both ACI and RP two-dimensional perovskite phases can be generated on the surface of the three-dimensional perovskite film, forming a heterojunction structure of a mixed-phase two-dimensional perovskite / three-dimensional perovskite film.

[0077] The combination of ACI and RP two-dimensional perovskite structures not only more comprehensively suppresses surface nonradiative recombination but also enables greater modification of the perovskite surface, producing a more n-type-oriented surface and promoting electron transport at the perovskite / electron transport layer interface. Furthermore, the small-sized ligands of ACI two-dimensional perovskite can partially infiltrate the 3D perovskite bulk, passivating bulk defects. Therefore, the mixed-phase two-dimensional perovskite prepared in this application combines the advantages of both types of two-dimensional perovskites, promoting carrier transport while suppressing nonradiative recombination, resulting in a significant improvement in device performance.

[0078] The inventors learned that prior to the application date, there were no reports on the generation of ACI two-dimensional perovskite and ACI two-dimensional perovskite / three-dimensional perovskite heterojunctions at the upper interface of three-dimensional perovskite films, nor had anyone prepared heterojunction structures of mixed-phase two-dimensional perovskite / three-dimensional perovskite films.

[0079] The method for preparing mixed-phase two-dimensional / three-dimensional heterojunction perovskite thin films disclosed in this application has the following advantages: the formation of mixed-phase two-dimensional perovskite can passivate defects on the perovskite surface, and the GA +Because of their small size, these perovskites can partially penetrate into the interior of perovskite films, significantly improving carrier lifetime at the perovskite film surface and in the bulk phase, and suppressing nonradiative recombination. The formation of mixed-phase two-dimensional perovskites makes the surface of three-dimensional perovskites more n-oriented and better matches the energy levels of the perovskite with the C60 electron transport layer, promoting carrier transport at the interface. A 1cm [structure / structure] based on a mixed-phase two-dimensional / three-dimensional perovskite heterojunction... 2 The device boasts a maximum photoelectric conversion efficiency of 21.65%, of which V OC The voltage is 1.225V, the FF is 85.58%, and the short-circuit current density (J) is... SC The value is 20.64 mA·cm. –2 .

[0080] Embodiments of this application also provide an optoelectronic device including a perovskite functional film layer, the perovskite functional film layer comprising: a three-dimensional perovskite film layer; and a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film layer, wherein the two-dimensional perovskite and the three-dimensional perovskite film layer constitute a heterojunction structure; the two-dimensional perovskite is: ACI two-dimensional perovskite, or a mixed-phase two-dimensional perovskite containing ACI two-dimensional perovskite.

[0081] The optoelectronic devices described in this application can be, for example, solar cell devices, light-emitting diodes (LEDs), and detectors. Solar cell devices using organic-inorganic hybrid perovskite as the light-absorbing layer can be fabricated using different bandgap perovskite materials to prepare single-junction perovskite solar cells or wide-bandgap (>1.6 eV) top cells suitable for tandem solar cells. Due to the adoption of the scheme described in this application, the open-circuit voltage and fill factor of the device are significantly improved by effectively suppressing non-radiative recombination and efficiently transporting interface charges, resulting in a substantial increase in the photoelectric conversion efficiency of the single-junction device.

[0082] The following are the experimental and test results of this application.

[0083] Experimental Example 1:

[0084] This embodiment provides an ACI two-dimensional perovskite / three-dimensional perovskite solar cell and its fabrication method, the fabrication method comprising:

[0085] Step 1: Prepare a substrate for a wide-bandgap perovskite thin film in advance. The substrate has a structure of glass / conductive substrate / hole transport layer.

[0086] Step 2: Dissolve lead iodide, cesium iodide, lead bromide, lead chloride, formamidine iodoformide, and chloromethylamine in a mixed solution of dimethylformamide and dimethyl sulfoxide in a certain proportion, and heat and stir until clear;

[0087] Step 3: Spin-coat the perovskite precursor liquid onto the substrate, inject the antisolvent, and finally anneal to obtain the perovskite film; the antisolvent does not dissolve any component of the wide-bandgap perovskite film; after the film cools down after annealing, take a portion of the prepared perovskite film for post-processing.

[0088] Step 4: Dissolve a certain concentration of GACl in IPA solution, and heat and stir until dissolved. Prepare solutions with concentrations of 1, 2, 3, 4, 5, and 10 mg / mL. –1 .

[0089] Step 5: Drop the GACl / IPA solution onto the prepared perovskite film surface and immediately rotate the substrate. Note that the time difference between the contact time between the solution and the perovskite substrate and the subsequent rotation time of the substrate should not exceed 3 seconds, otherwise a yellow perovskite film (yellow phase) will be formed. Yellow phase perovskite has no photoelectric properties.

[0090] Step Six: After completing spin coating as in Step Five, immediately transfer the substrate to a hot plate at 100°C for annealing for 5 minutes. After annealing, the perovskite film will appear purple.

[0091] After cooling, some samples were selected for XRD, steady-state fluorescence (PL) and scanning electron microscopy (SEM) surface morphology tests. The tests showed that ACI two-dimensional perovskite was generated on the surface of the three-dimensional perovskite film. The perovskite on the surface of the original perovskite film was transformed into ACI two-dimensional perovskite after treatment, and the perovskite under the surface is the three-dimensional perovskite film at this time.

[0092] Step 7: After annealing, transfer all samples to a vacuum evaporation chamber to deposit the electron transport layer C60 and the barrier layer BCP. Finally, deposit the metal electrode and perform efficiency testing.

[0093] Comparative Example 1 (Standard Preparation): A perovskite film identical to that in Experimental Example 1 was used, but without the addition of GACl IPA solution. Figure 3 The corresponding test curve is marked as "0" for the concentration of the treatment solution.

[0094] Tests: The samples of Comparative Example 1 (labeled as having a GACl IPA solution concentration of "0" for treatment) and Experimental Example 1 (labeled as having a corresponding GACl IPA solution concentration of "1, 2, 3, 4, 5, 10" mg / mL for treatment) were subjected to XRD tests. The sample films with concentrations of 0 mg / mL and 2 mg / mL were selected for steady-state fluorescence tests and surface SEM tests.

[0095] Figure 3The powder XRD results are shown when the concentration of GACl in the treatment solution is increased from 0 to 10 mg / mL. Four new peaks appear at 6.73, 9.32, 11.55 and 12.96. These characteristic peaks correspond to two-dimensional ACI perovskites, proving the formation of the ACI structure.

[0096] Steady-state fluorescence tests were then performed on the samples from Comparative Example 1 and Experimental Example 1 (GACl IPA solution concentration 2 mg / mL). After comparison, three new peaks appeared in the sample from Experimental Example 1 at 625, 656, and 692 nm. These three peaks belong to GAA. n Pb n X 3n+1 (This is the chemical formula of the ACI structure); the three peaks correspond to n=2, 3, and 4 respectively, further proving the formation of the ACI structure and the width distribution of the two-dimensional perovskite layer.

[0097] Figure 4 Comparative Example 1 (SEM measurements before and after GACl treatment) Figure 4 The Chinese label indicates "three-dimensional" and the sample of Experimental Example 1 ( Figure 4 The morphology comparison images of the films labeled "3D / ACI 2D" show that in Comparative Example 1, the 3D film has saturated 3D grains, and the bright-colored substance is PbX2 (lead halides have relatively poor conductivity and are generally bright-colored). The right image (labeled "3D / ACI 2D") shows obvious micron-sized flake-like substances after treatment with 2 mg / mL GACl solution (clearly different from PbX2). The combination of the above three tests confirms that there is a new substance on the surface of the 3D perovskite, and this new substance is ACI 2D perovskite.

[0098] In addition, some samples from Experiment 1 after spin-coating with GACl were continued with the subsequent perovskite solar cell fabrication process, followed by electrical testing. The box plots for these cells' electrical tests are shown below. Figures 5(a) to 5(d) As shown in the figure, only the box plots of the electrical tests of the three samples from Experimental Example 1 with corresponding GACl treatment solution concentrations of 1.5 mg / mL, 2 mg / mL, and 2.5 mg / mL, which showed better results, are shown.

[0099] in, Figures 5(a) to 5(d) The open-circuit voltages (V) of the battery samples corresponding to the three GACl concentrations are shown below. OC Photovoltaic conversion efficiency (PCE), short-circuit current (J) SC Experimental data on the fill factor (FF) and fill factor (FF). Simultaneously, the open-circuit voltage (V) of the corresponding optimal cell (as a control standard) without GACl / IPA solution treatment. OC The voltage is 1.16V, the optical conversion efficiency (PCE) is 18.53%, and the short-circuit current (J) is... SC The value is 20.64 mA·cm.–2 The fill factor (FF) is 77.25%. (Comparison) Figures 5(a) to 5(d) The electrical experimental data of the battery cells corresponding to these three GACl concentrations are shown, and the concentration of 2 mg·mL can be determined. –1 The battery cell corresponding to the isopropanol solution of guanidine chloride showed the best test results, with its open-circuit voltage (V) OC The voltage is 1.21V, the photoelectric conversion efficiency (PCE) is 20.18%, and the short-circuit current (J) is... SC The value is 20.12 mA·cm. –2 The fill factor (FF) was 82.45%, which was a significant improvement compared to the standard (without GACl / IPA solution treatment).

[0100] Cause Analysis: By treating the three-dimensional perovskite film with GACl / IPA solution, a slightly n-type perovskite surface is obtained. This forms a heterojunction structure of ACI two-dimensional perovskite / three-dimensional perovskite on the upper layer of the perovskite light-absorbing layer, which improves carrier transport at the interface between the perovskite and the transport layer. At the same time, the ACI two-dimensional perovskite passivates surface defects in the film, and guanidinium cations can partially enter the interior of the three-dimensional perovskite film, passivating bulk defects in the film. This achieves simultaneous suppression of nonradiative recombination on the perovskite surface and in the bulk phase, greatly improving the photoelectric efficiency of the perovskite solar cell.

[0101] Experimental Example 2:

[0102] This application also provides a method for fabricating a perovskite solar cell with a mixed-phase two-dimensional / three-dimensional perovskite heterojunction, comprising the following steps:

[0103] Step 1: Prepare a substrate for a wide-bandgap perovskite thin film in advance. The substrate has a structure of glass / conductive substrate / hole transport layer.

[0104] Step 2: Dissolve lead iodide, cesium iodide, lead bromide, lead chloride, formamidine iodoformide, and chloromethylamine in a mixed solution of dimethylformamide and dimethyl sulfoxide in a certain proportion, and heat and stir until clear;

[0105] Step 3: Spin-coat the perovskite precursor liquid onto the substrate, inject the antisolvent, and finally anneal to obtain the perovskite film; the antisolvent does not dissolve any component of the wide-bandgap perovskite film; after the film cools down after annealing, take a portion of the prepared perovskite film for post-processing.

[0106] Step 4: Dissolve GACl and OAMI in IPA at a specific concentration ratio to prepare a mixed IPA solution of GACl and OAMI. In all prepared treatment solutions, the concentration of GACl is 2 mg / mL. –1 The concentrations of oleamine iodine were 0.2, 0.4, and 0.6 mg / mL, respectively. –1 .

[0107] Step 5: Rapidly spin-coat the solution obtained in Step 4 onto the perovskite film obtained in Step 2;

[0108] Step 6: After completing spin coating as in Step 5, immediately transfer the substrate to a hot stage at 100°C for annealing for 5 minutes to obtain a mixed-phase two-dimensional / three-dimensional perovskite heterojunction film.

[0109] After cooling, some samples were selected for grazing incidence X-ray diffraction (GIXRD), transient fluorescence, and SEM surface morphology testing. The tests showed that a mixed two-dimensional perovskite of ACI and RP was formed on the surface of the three-dimensional perovskite film, and the perovskite below the surface was the three-dimensional perovskite film mentioned above.

[0110] Step 7: After annealing, transfer all samples to a vacuum evaporation chamber to deposit the electron transport layer C60 and the barrier layer BCP. Finally, deposit the metal electrode and perform efficiency testing.

[0111] Comparative Example 2 (Standard Preparation): The same steps as in Experimental Example 2 were used, except that no treatment solution was added for post-treatment.

[0112] Test: Partial samples of Experiment Example 2 ( Figures 6(a) to 6(d) The samples from Comparative Example 2 were labeled as "GACl / 0.2OAmI", "GACl / 0.4OAmI", and "GACl / 0.6OAmI" according to their concentrations. Figures 6(a) to 6(d) The labels are "Ref" (indicating no treatment with any solution), and the treatment solution in Experimental Example 1 was 2 mg / mL. –1 The sample ( Figures 6(a) to 6(d) Electrical tests were conducted using the symbol marked "GACl".

[0113] Figures 6(a) to 6(d) The open-circuit voltages (V) of the battery samples corresponding to the three mixed concentrations of GACl / OAmI treatment solution are shown below. OC Power conversion efficiency (PCE), short-circuit current (J) SC Experimental data for GACl / 0.4OAmI and filler factor (FF) were compared. The comparison was made with the label "GACl / 0.4OAmI" (corresponding to a mixed IPA treatment solution of GACl and OAmI, where the concentration of GACl was 2 mg / mL). –1 The concentration of OAmI was 0.4 mg·mL. –1 Open circuit voltage under certain conditions (V) OC It has the best power conversion efficiency (PCE) and fill factor (FF), while the short-circuit current (J) is the lowest. SC The decrease is the smallest compared to the standard part.

[0114] The electrical characteristic parameters of standard (untreated) solar cell devices based on ACI two-dimensional / three-dimensional perovskite heterojunction films generated by GACl / IPA solution treatment, RP two-dimensional / three-dimensional perovskite heterojunction films generated by OAMI solution treatment, and ACI / RP mixed-phase two-dimensional / three-dimensional perovskite heterojunction films generated by a mixed GACl and OAMI IPA solution treatment are summarized in the table below. Considering all factors, the test results of the electrical characteristic parameters of solar cell devices based on ACI two-dimensional / three-dimensional perovskite heterojunction films, or those based on ACI / RP mixed-phase two-dimensional / three-dimensional perovskite heterojunction films, are the best. V OC The voltages are 1.21V and 1.23V respectively, J SC 20.12 mA·cm –2 and 0.40 mA·cm –2 The FF values ​​were 82.45% and 83.73%, respectively, and the PCE values ​​were 20.18 mA·cm⁻¹. –2 and 20.94 mA·cm –2 Among them, the mixed-phase two-dimensional / three-dimensional heterojunction perovskite-based cells exhibited the best performance.

[0115] Ref GACl OAmI GACl / OAmI <![CDATA[V OC (V)]]> 1.16 1.21 1.14 1.23 <![CDATA[J SC (mA cm –2 )]]> 20.64 20.12 20.01 20.40 FF (%) 77.25 82.45 79.05 83.73 PCE (%) 18.53 20.18 17.97 20.94

[0116] Solar cell devices based on ACI and RP mixed two-dimensional / three-dimensional perovskite heterojunction thin films (light-collecting area 1cm²) 2 The photoelectric conversion performance of the device was tested. The concentration of GACl in the processing solution corresponding to the heterojunction thin film of this device was 2 mg·mL⁻¹. –1 The concentration of OAmI was 0.4 mg·mL. –1 The photoelectric conversion performance of this device was tested by placing it under standard sunlight and performing voltage-current curve scanning. The reverse scan photoelectric conversion efficiency of this device reached 21.28%, and the forward scan efficiency reached 21.65%.

[0117] Three-dimensional perovskite films (untreated with any solution) were selected and treated with a mixed IPA solution of GACl and OAmI (GACl concentration 2 mg / mL). –1 The concentration of OAmI was 0.4 mg·mL. –1 The mixed-phase two-dimensional / three-dimensional heterojunction film layer (which showed good electrical test results) was subjected to SEM surface morphology testing, GIXRD testing, TRPL spectrum testing, and surface potential testing. The results are as follows: Figures 8-12 As shown.

[0118] Figure 8This study compares the morphology of three-dimensional perovskite films with two-dimensional / three-dimensional perovskite heterojunction films mixed with ACI and RP. The testing method involved scanning the surface morphology of the perovskite films before and after treatment using a field emission scanning electron microscope. Unlike the well-formed grains of three-dimensional perovskite, the film treated with GACl / OAmI solution exhibited distinctly discontinuous, plate-like structures on its surface, and the surface contrast was significantly different. Figure 4 Thin films treated with GACl / IPA solution alone.

[0119] Figure 9 These are the GIXRD patterns of a three-dimensional perovskite thin film and a mixed-phase two-dimensional / three-dimensional perovskite heterojunction thin film. The post-treated film shows new peaks at 4.47°, 6.68°, 9.32°, 11.55°, and 12.96°, indicating the formation of new phases. The 4.47° peak is characteristic of the RP phase, while the 6.68°, 9.32°, and 12.96° peaks are characteristic of the ACI phase. The GIXRD results confirm the formation of a mixed-phase two-dimensional / three-dimensional heterojunction in the post-treated film.

[0120] Figure 10 This paper compares the time-resolved fluorescence (TRPL) spectra of three-dimensional perovskite films and mixed-phase two-dimensional / three-dimensional perovskite heterojunction films. The testing method involved exciting both types of perovskite films with the same wavelength of excitation light and measuring the time-resolved fluorescence intensity. The results show that the carrier lifetime of the mixed-phase two-dimensional / three-dimensional perovskite heterojunction film is significantly longer than that of the three-dimensional perovskite film, indicating the presence of suppressed nonradiative recombination in the mixed-phase two-dimensional / three-dimensional perovskite heterojunction film.

[0121] Figure 11 The surface potential of three-dimensional thin films and mixed-phase two-dimensional / three-dimensional perovskite heterojunction thin films. Figure 12 This refers to the energy level arrangement of the two components with C60. The perovskite thin film was tested using the Kelvin probe method, and the results are as follows... Figure 11 As shown, the surface potential of the miscible two-dimensional / three-dimensional perovskite film is higher than that of the three-dimensional perovskite film, implying a lower surface work function, meaning that electrons on the surface of the miscible two-dimensional / three-dimensional perovskite film are more easily released from their bonds. The energy level structure of the perovskite film can be calculated using the results of ultraviolet photoelectron spectroscopy and ultraviolet-visible spectrophotometry, as shown below. Figure 12 As shown, the mixed-phase two-dimensional / three-dimensional perovskite heterojunction has energy level positions that are more matched with C60, and the lower work function also represents a more n-level surface electronic structure state. Electrons on the treated perovskite surface are more easily transferred to the C60 transport layer, which improves the carrier transport performance of the perovskite / C60 interface. Figure 12 The results show that the construction of mixed two-dimensional / three-dimensional perovskite heterojunctions improves the carrier transport performance of the perovskite / C60 interface and reduces interface energy loss.

[0122] The above-mentioned mixed two-dimensional / three-dimensional heterojunction perovskite film was integrated on a double-textured silicon heterojunction (SHJ) bottom cell to form a 1cm layer. 2 Monolithic multilayer devices. The champion device exhibits a hysteresis-free JV curve, with a PCE of 31.19% and V0. OC It is 1.904V, J SC 19.61 mA·cm –2 The FF was 83.52%. At the highest power point, after continuous irradiation for 30 minutes under simulated light (1 sun, AM 1.5G), a steady-state output efficiency of 31.16% was obtained. This unencapsulated solar cell was certified by the National Institute of Metrology in China, with a PCE of 30.41% and J... SC 19.7 mA·cm –2 V OC The voltage is 1.86V, and the FF is 82.95%. A steady-state PCE of 30.16% was also achieved.

[0123] We subjected the packaged multilayer device to damp heat testing (85°C, 85% relative humidity, IEC 61215:2021 standard). After more than 1000 hours, the device maintained 98% of its initial efficiency, demonstrating that our 2D / 3D heterojunction perovskite itself and the interface layer have sufficient tolerance to thermal stress. Furthermore, in ambient air at approximately 25°C, under continuous sunlight of one solar intensity (AM 1.5G, 100mW·cm⁻¹), the device also showed good performance. –2 Under full solar irradiation, the tandem solar cell maintained 92% of its initial efficiency after tracking near the highest power point for 230 hours, making it one of the most stable perovskite / silicon tandem solar cells reported to date under full solar irradiation.

[0124] Without conflict, the technical features of the embodiments of this application can be used in any combination.

[0125] The above embodiments have been described in conjunction with the accompanying drawings. The specific implementation of this application is not limited to the above embodiments, and non-essential modifications made based on the above invention are still within the protection scope of the invention.

Claims

1. A perovskite solar cell, comprising a perovskite light-absorbing layer, characterized in that, The perovskite light-absorbing layer comprises: a three-dimensional perovskite film layer, and a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film layer; wherein, The two-dimensional perovskite and the three-dimensional perovskite film form a heterojunction structure, and, The two-dimensional perovskite is a miscible two-dimensional perovskite containing ACI two-dimensional perovskite; the miscible two-dimensional perovskite containing ACI two-dimensional perovskite includes: a miscible two-dimensional perovskite containing a mixture of ACI two-dimensional perovskite and RP two-dimensional perovskite. The second material used to generate RP two-dimensional perovskite includes a mixed solution of guanidine chloride and oleamine iodine.

2. The perovskite solar cell as described in claim 1, characterized in that, The spacer cations of the ACI two-dimensional perovskite are alternating guanidine ions and a first cation, the first cation being the same as the A-site cation of the three-dimensional perovskite film.

3. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell further includes a C60 electron transport layer, which is formed on the two-dimensional perovskite.

4. A multi-junction tandem solar cell, characterized in that, Includes a perovskite sub-cell, wherein the perovskite sub-cell is a perovskite solar cell as described in any one of claims 1-3.

5. A method for fabricating a perovskite solar cell, comprising a step of fabricating a perovskite light-absorbing layer, characterized in that, The fabrication process of the perovskite light-absorbing layer includes: Preparation of three-dimensional perovskite films; A treatment solution is coated onto the three-dimensional perovskite film. The treatment solution includes at least a first material for generating ACI two-dimensional perovskite; the treatment solution also includes a second material for generating RP two-dimensional perovskite; the treatment solution includes a mixed solution of guanidine chloride and oleamine iodine. Annealing is performed to generate a two-dimensional perovskite at the upper interface of the three-dimensional perovskite film, the two-dimensional perovskite comprising a miscible two-dimensional perovskite of ACI two-dimensional perovskite; the miscible two-dimensional perovskite comprising ACI two-dimensional perovskite includes a miscible two-dimensional perovskite of ACI two-dimensional perovskite and RP two-dimensional perovskite.

6. The preparation method according to claim 5, characterized in that, The first material used to generate ACI two-dimensional perovskite includes: guanidine salt.

7. The preparation method according to claim 5, characterized in that, The first material used to generate ACI two-dimensional perovskite includes: guanidine halide.

8. The preparation method according to claim 6 or 7, characterized in that, The treatment solution has a concentration of 1.5 mg / mL. –1 ~2.5 mg·mL –1 A solution of guanidine chloride in isopropanol.

9. The preparation method according to claim 6 or 7, characterized in that, The concentration of the treatment solution is 2 mg·mL⁻¹ –1 A solution of guanidine chloride in isopropanol.

10. The preparation method according to claim 5, characterized in that, The mass concentration ratio of guanidine chloride to oleamine iodine is (1.5:0.4) to (2.5:0.4).

11. The preparation method according to claim 5, characterized in that, The mass concentration ratio of guanidine chloride to oleamine iodine is 2:0.

4.

12. The preparation method according to any one of claims 5 to 11, characterized in that, The process of generating a two-dimensional perovskite at the upper interface of the three-dimensional perovskite film includes: The treatment solution is coated onto the surface of the three-dimensional perovskite film in the first time to avoid the formation of yellow phase perovskite. After coating and forming the film, annealing is performed immediately, and after cooling, a two-dimensional perovskite is formed on the surface of the three-dimensional perovskite film.

13. The preparation method according to claim 12, characterized in that, The treatment solution is a mixed isopropanol solution of guanidine chloride and oleamine iodine. The step of coating the surface of the three-dimensional perovskite film with the treatment solution within a first time includes: A solution of guanidine chloride and oleoamine iodine in isopropanol is dropped onto the three-dimensional perovskite film and immediately spin-coated, wherein the time from the first contact between the mixed isopropanol solution of guanidine chloride and oleoamine iodine and the surface of the three-dimensional perovskite film to the second time of the start of coating does not exceed 3 seconds.

14. An optoelectronic device comprising a perovskite functional film layer, characterized in that, The perovskite functional membrane comprises: a three-dimensional perovskite film layer; and a two-dimensional perovskite distributed on the interface of the three-dimensional perovskite film layer, wherein the two-dimensional perovskite and the three-dimensional perovskite film layer constitute a heterojunction structure; the two-dimensional perovskite is a miscible two-dimensional perovskite containing ACI two-dimensional perovskite; the miscible two-dimensional perovskite containing ACI two-dimensional perovskite includes: a miscible two-dimensional perovskite containing both ACI two-dimensional perovskite and RP two-dimensional perovskite phases. The second material used to generate RP two-dimensional perovskite includes a mixed solution of guanidine chloride and oleamine iodine.

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