Perovskite solar cell and preparation method thereof

Abstract

The application belongs to the technical field of perovskite solar cells, and particularly relates to a perovskite solar cell and a preparation method thereof. The application provides a perovskite solar cell, wherein the perovskite solar cell comprises an interface buffer layer, and the interface buffer layer is a material containing ytterbium elements. The application uses the material containing ytterbium elements as the interface buffer layer of the perovskite solar cell, the work function of the material containing ytterbium elements is low, which is beneficial to the formation of ohmic contact, the extraction of electrons, and the reduction of the recombination of carriers at the interface, not only realizing high photoelectric conversion efficiency, but also significantly improving the stability of the perovskite solar cell device, especially the thermal stability, due to the chemical stability and thermal stability of the material containing ytterbium elements.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a perovskite solar cell and its preparation method. Background Technology

[0002] Perovskite solar cells have received increasing attention due to their simple fabrication process, low cost, and high performance. Currently, the photoelectric conversion efficiency of single-junction perovskite solar cell devices has reached 25.7%, which is very close to the photoelectric conversion efficiency record of monocrystalline silicon solar cells.

[0003] Based on their structure, perovskite solar cells can be classified into conventional and inverted structures. Common conventional perovskite solar cells include those with and without an electron transport layer. Conventional perovskite solar cells consist of a transparent conductive substrate, an electron transport layer, a perovskite layer, a hole transport layer, and a metal electrode, stacked sequentially. Inverted perovskite solar cells consist of a transparent conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, an interface buffer layer, and a metal electrode, stacked sequentially.

[0004] In addition, multi-junction (tandem) solar cells have enormous potential to break the Shockley-Quisher (SQ) efficiency limit of single-junction solar cells. Perovskite solar cells are ideal candidates for multi-junction cells due to their tunable bandgap, high photoelectric conversion efficiency, and ease of fabrication. This makes them easy to combine with many other types of solar cells, such as silicon, copper indium gallium selenide (CIGS), narrow bandgap perovskite solar cells, organic and quantum dot solar cells.

[0005] Inverted perovskite solar cells have attracted widespread attention due to their ability to be processed at low temperatures, lower device hysteresis, better device stability, and suitability for fabricating tandem perovskite devices. Currently, most inverted perovskite solar cell structures use bath copper phosphate (BCP) as an interface buffer layer. However, the glass transition temperature of organic material BCP is too low (85℃), and it is unstable under light, which severely limits the long-term stability of perovskite solar cells. Summary of the Invention

[0006] The purpose of this invention is to provide a perovskite solar cell and its preparation method. The perovskite solar cell provided by this invention significantly improves the thermal stability of the device while achieving a photoelectric conversion efficiency comparable to that of devices using BCP as an interface buffer layer.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The present invention provides a perovskite solar cell, the perovskite solar cell including an interface buffer layer, the interface buffer layer being a material containing ytterbium.

[0009] Preferably, the chemical composition of the interface buffer layer includes ytterbium oxide.

[0010] Preferably, the chemical composition of the interface buffer layer further includes elemental ytterbium.

[0011] Preferably, the perovskite solar cell includes an inverted structure cell, a formal structure cell, or a stacked structure cell consisting of an inverted structure and a formal structure.

[0012] Preferably, the thickness of the interface buffer layer is 0.5 to 10 nm.

[0013] Preferably, the perovskite solar cell is an inverted structure cell, the interface buffer layer is located between the electron transport layer and the metal electrode, and the chemical composition of the electron transport layer is a carbon compound.

[0014] Preferably, the carbon compound includes [6,6]-phenyl-C61-butyrate isomethyl ester, [6,6]-phenyl-C71-butyrate isomethyl ester, or C 60 .

[0015] Preferably, the perovskite solar cell is a formal perovskite solar cell without an electron transport layer structure, and the interface buffer layer is located between the transparent conductive substrate and the perovskite layer.

[0016] Preferably, the chemical composition of the hole transport layer in the formal electron-transport-layer-less perovskite solar cell includes bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), poly[bis(4-phenyl)(4-butylphenyl)amine], poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (Poly-TPD), and nickel oxide (NiO). x (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz), [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz) or [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz).

[0017] Preferably, the perovskite solar cell is a perovskite solar cell with a formal electron transport layer structure, and the interface buffer layer is located between the electron transport layer and the perovskite layer.

[0018] This invention provides a perovskite solar cell comprising an interface buffer layer made of a ytterbium-containing material. This invention replaces the biofilm polymer (BCP) buffer layer (YCP) with a ytterbium-containing material as the interface buffer layer in the perovskite solar cell. Because the ytterbium-containing material has a low work function, it facilitates the formation of ohmic contacts, promotes electron extraction, and reduces carrier recombination at the interface. This not only achieves high photoelectric conversion efficiency but also significantly improves the stability of the perovskite solar cell device, especially its thermal stability, due to the chemical and thermal stability of the ytterbium-containing material. The results of the embodiments show that the perovskite solar cell provided by this invention, using a ytterbium-containing material as the interface buffer layer, significantly improves device stability, especially thermal stability. Existing organic BCP buffer layers are unstable under thermal conditions, easily agglomerating or degrading, leading to a decrease in device stability. Using a stable ytterbium-containing material as the interface buffer layer can prevent the diffusion of electrode metal atoms and suppress the oxidation of the metal electrode (e.g., ...). Figure 1 The test results show that the interface stability is greatly improved, resulting in highly stable perovskite solar cells (such as...). Figure 2 (Test results); Meanwhile, the perovskite solar cell provided by this invention uses a ytterbium-containing material as an interface buffer layer, without sacrificing the device's photoelectric conversion performance. This facilitates the formation of an ohmic contact between the electron transport layer and the metal electrode, reducing carrier recombination at the interface. This invention achieves an ultra-high photoelectric conversion performance of nearly 25% using a ytterbium-containing material as an interface buffer layer. External quantum efficiency curve testing also verifies the reliability of the short-circuit current density in the JV test (e.g., Figure 3 (Test results).

[0019] Furthermore, in this invention, the perovskite solar cell includes an inverted structure, a formal structure, or a stacked structure composed of an inverted structure and a formal structure; the interface buffer layer of the inverted perovskite solar cell is located between the electron transport layer and the metal electrode; the interface buffer layer of the formal perovskite solar cell is located between the transparent conductive substrate and the perovskite layer or between the electron transport layer and the perovskite layer. In the inverted perovskite solar cell, the interface buffer layer containing ytterbium is located between the electron transport layer and the metal electrode, avoiding the formation of Schottky barrier-induced carrier recombination at the interface between the electron transport layer and the metal electrode, which is detrimental to carrier extraction; at the same time, it prevents metal atoms of the electrode from diffusing into the electron transport layer or even the perovskite photoactive layer, forming defect-induced carrier recombination, which greatly reduces the stability and photoelectric transmission performance of the device. In a formally structured perovskite solar cell, an interface buffer layer containing ytterbium is located between the transparent conductive substrate and the perovskite layer, or between the electron transport layer and the perovskite layer. When located between the transparent conductive substrate and the perovskite layer, the interface buffer layer containing ytterbium can reduce the work function of the transparent conductive substrate, which is more conducive to electron extraction. When located between the electron transport layer and the perovskite layer, it can help form an ohmic contact, which is beneficial to electron extraction, improving the thermal stability of the device while maintaining high photoelectric transmission performance. Attached Figure Description

[0020] Figure 1 This is a comparative illustration of the perovskite solar cell interface buffer layer after aging, prepared in Example 1 of the present invention and in prior art document 1.

[0021] Figure 2 The perovskite solar cell prepared in Example 1 of this invention has the following curves: photoelectric conversion efficiency, statistical distribution of device performance, steady-state output, and external quantum efficiency of the cell.

[0022] Figure 3 The image shows a comparison of the stability of perovskite solar cell devices prepared in Example 1 of this invention and in prior art document 1, as well as the maximum power output curve of the narrow bandgap perovskite solar cell in Example 1.

[0023] Figure 4 This is a schematic diagram of the formal structure and the inverted structure of the perovskite solar cell of this invention. Detailed Implementation

[0024] The present invention provides a perovskite solar cell, the perovskite solar cell including an interface buffer layer, the interface buffer layer being a material containing ytterbium.

[0025] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0026] In this invention, the chemical composition of the interface buffer layer preferably includes ytterbium oxide.

[0027] As one or more specific embodiments of the present invention, the chemical composition of the interface buffer layer is ytterbium oxide.

[0028] In this invention, the chemical composition of the interface buffer layer preferably further includes ytterbium.

[0029] As one or more specific embodiments of the present invention, the chemical composition of the interface buffer layer is a mixture of ytterbium oxide and elemental ytterbium.

[0030] In this invention, when the chemical composition of the interface buffer layer is a mixture of ytterbium oxide and elemental ytterbium, there are no special requirements on the mass ratio of the ytterbium oxide and elemental ytterbium.

[0031] In this invention, the thickness of the interface buffer layer is preferably 0.5 to 10 nm, more preferably 1.5 nm.

[0032] In this invention, the perovskite solar cell preferably comprises an inverted structure cell, a normal structure cell, or a stacked structure cell consisting of an inverted structure and a normal structure. This invention does not impose any special requirements on the specific stacking method of the stacked structure cell consisting of the inverted structure and the normal structure.

[0033] In this invention, such as Figure 4 As shown in the left figure, the inverted perovskite solar cell preferably consists of a transparent conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, an interface buffer layer, and a metal electrode, which are stacked sequentially. The interface buffer layer is located between the electron transport layer and the electrode. In this invention, the chemical composition of the electron transport layer is preferably a carbon compound, which preferably includes isomethyl [6,6]-phenyl-C61-butyrate (

[60] PCBM), isomethyl [6,6]-phenyl-C71-butyrate (

[70] PCBM), or C 60 .

[0034] In this invention, the formally structured perovskite solar cell includes formally structured perovskite solar cells without an electron transport layer and formally structured perovskite solar cells with an electron transport layer. For example... Figure 4 As shown in the middle figure, the preferred electron transport layer-free perovskite solar cell structure comprises a transparent conductive substrate, an interface buffer layer, a perovskite layer, a hole transport layer, and a metal electrode, which are sequentially stacked. The interface buffer layer is located between the transparent conductive substrate and the perovskite layer. In this invention, the chemical composition of the hole transport layer of the preferred electron transport layer structure of the perovskite solar cell structure includes PTAA, Poly-TPD, PEDOT:PSS, and NiO. xMeO-2PACz, 2PACz, or Me-4PACz.

[0035] like Figure 4 As shown in the right-hand figure, the formal perovskite solar cell with an electron transport layer structure includes a transparent conductive substrate, an electron transport layer, an interface buffer layer, a perovskite layer, a hole transport layer, and a metal electrode, which are stacked sequentially. The interface buffer layer is located between the electron transport layer and the perovskite layer.

[0036] In inverted perovskite solar cells, when the interface buffer layer is ytterbium oxide, it can not only form an ohmic contact at the electron transport layer and electrode interface, but also suppress atomic diffusion at the electrode, thereby obtaining a highly efficient and stable perovskite solar cell.

[0037] In inverted perovskite solar cells, this invention, by controlling the thickness of the interface buffer layer to 0.5–10 nm, effectively avoids the formation of a Schottky barrier at the electron transport layer and electrode interface, preventing induced carrier recombination and facilitating carrier extraction. Simultaneously, it effectively prevents electrode atoms from diffusing into the electron transport layer and even the perovskite photoactive layer, thus avoiding defect-induced carrier recombination and the resulting reduction in device stability and photoelectric conversion performance. By controlling the thickness of the interface buffer layer to 0.5–10 nm, this invention not only forms an ohmic contact at the electron transport layer and metal electrode interface but also suppresses electrode atomic diffusion, thereby obtaining a highly efficient and stable perovskite solar cell.

[0038] In a perovskite solar cell with a formal electron transport layer-free structure, this invention provides a ytterbium-containing material interface buffer layer of 1.5 nm, which effectively reduces the work function of the transparent conductive substrate, forms an ohmic contact, and is more conducive to electron extraction.

[0039] In perovskite solar cells with a formal electron transport layer structure, this invention provides an interface buffer layer containing ytterbium of 0.5–10 nm, which reduces the work function of the electron transport layer and facilitates electron extraction.

[0040] This invention provides a method for fabricating the perovskite solar cell described above, wherein the fabrication of the interface buffer layer in the perovskite solar cell includes:

[0041] The interface buffer layer was obtained by vacuum evaporation followed by oxidation using ytterbium as the evaporation source.

[0042] In this invention, the vacuum evaporation is preferably carried out in an evaporation chamber.

[0043] In this invention, before performing the vacuum evaporation, it is preferable to place the ytterbium metal at the evaporation source position in the evaporation chamber; then, the vacuum level of the evaporation chamber is adjusted, preferably to 4 × 10⁻⁶.-4 At Pa, the present invention preferably adjusts the temperature at the evaporation source location to perform the vacuum evaporation.

[0044] In this invention, the evaporation rate during vacuum evaporation is preferably [missing information].

[0045] In this invention, the vacuum degree during vacuum evaporation is preferably 4 × 10⁻⁶. -4 Pa.

[0046] In this invention, during the vacuum evaporation process, the rotation speed of the substrate carrying the interface buffer layer is 18 r / min.

[0047] In this invention, after vacuum evaporation, since ytterbium is easily oxidized, the ytterbium layer is oxidized to obtain the interface buffer layer.

[0048] In this invention, when the perovskite solar cell is preferably of an inverted structure, the vacuum evaporation is performed on the surface of the electron transport layer. During the vacuum evaporation, the substrate supporting the interface buffer layer is an inverted substrate containing the electron transport layer surface layer. In this invention, the method for preparing the inverted substrate containing the electron transport layer surface layer preferably includes the following steps: sequentially preparing a hole transport layer, a perovskite layer, and an electron transport layer on the surface of a transparent conductive substrate.

[0049] In this invention, when the perovskite solar cell is a formal structure, the vacuum evaporation is performed on the surface of a transparent conductive substrate or the surface of an electron transport layer. During the vacuum evaporation, the substrate supporting the interface buffer layer is either a transparent conductive substrate or a formal substrate containing an electron transport layer. In this invention, the method for preparing the formal substrate containing the electron transport layer preferably includes the following steps: preparing an electron transport layer on the surface of the transparent conductive substrate.

[0050] In this invention, the transparent conductive substrate is preferably ITO or FTO glass.

[0051] In this invention, the preferred material for the electron transport layer is C. 60 .

[0052] The present invention does not have any special requirements for the preparation methods of the electron transport layer, hole transport layer, perovskite layer and electrodes of the perovskite solar cell. The preparation methods of the electron transport layer, hole transport layer, perovskite layer and electrodes of perovskite solar cells that are well known to those skilled in the art can be used.

[0053] In this invention, prior to the fabrication of the perovskite solar cell, the conductive substrate is preferably cleaned and treated with UV-O3 sequentially.

[0054] In this invention, the cleaning process preferably includes the following steps: ultrasonically cleaning the conductive substrate sequentially with a cleaning agent, ultrasonically cleaning with deionized water, ultrasonically cleaning with acetone, and ultrasonically cleaning with isopropanol. The ultrasonic cleaning time with the cleaning agent is preferably 15 minutes, the ultrasonic cleaning time with deionized water is preferably 15 minutes, the ultrasonic cleaning time with acetone is preferably 15 minutes, and the ultrasonic cleaning time with isopropanol is preferably 15 minutes.

[0055] In this invention, the UV-O3 treatment time is 15 minutes. This invention does not have special requirements regarding the specific implementation process of the UV-O3 treatment. Preferably, this invention uses the UV-O3 treatment to remove residual organic matter on the surface of the conductive substrate and improve the work function.

[0056] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] according to Figure 4 The structure shown in the left diagram:

[0059] The ITO transparent conductive substrate was cleaned by ultrasonic cleaning for 15 minutes each using glass cleaner, deionized water, acetone, and isopropanol, respectively.

[0060] The cleaned ITO transparent conductive substrate was treated with UV-O3 for 15 minutes to remove residual organic matter on the surface of the transparent ITO conductive substrate and improve its work function.

[0061] 1. For narrow bandgap perovskite solar cells (Rb) with a bandgap of 1.55 eV. 0.05 Cs 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 3) The perovskite layer preparation process is as follows:

[0062] A self-assembled monolayer of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) was dissolved in isopropanol to obtain a hole transport layer precursor solution with a mass concentration of 0.5 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 3000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 100 °C for 10 min to obtain the hole transport layer.

[0063] A mixed solution of CsI, RbI, MABr, FAI, PbI2 and PbBr2 is coated onto the surface of the interface layer to obtain a mixed solution layer of CsI, RbI, MABr, FAI, PbI2 and PbBr2. The mixed solution layer of CsI, RbI, MABr, FAI, PbI2 and PbBr2 is then annealed to obtain the perovskite layer.

[0064] In this invention, the solvent in the mixed solution of CsI, RbI, MABr, FAI, PbI2 and PbBr2 is preferably a blend of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (DMF:DMSO = 4:1). The preferred concentrations of CsI, RbI, MABr, FAI, PbI2 and PbBr2 in the mixed solution are 19.5 mg / mL, 15.9 mg / mL, 8.4 mg / mL, 19.5 mg / mL, 656.9 mg / mL, and 27.5 mg / mL. The coating is preferably spin coating, and the spin coating speed is preferably 1000 rpm × 10 s in the first step and 3000 rpm × 30 s in the second step. 150 μL of anti-solvent chlorobenzene is added dropwise in the 15th second of the second step. The annealing temperature is preferably 100℃ and the annealing holding time is preferably 10 min.

[0065] 2. For medium-bandgap perovskite solar cells with a bandgap of 1.61 eV (Cs 0.05 FA 0.85 MA 0.10 ) 0.95 Pb(I 0.85 Br 0.15 3) The perovskite layer preparation process is as follows:

[0066] Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was dissolved in toluene to obtain a hole transport layer precursor solution with a mass concentration of 2 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 5000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 120 °C for 10 min to obtain the hole transport layer.

[0067] Phenethylamine iodine was dissolved in isopropanol at a concentration of 10 mg / mL and shaken thoroughly to ensure complete dissolution. The phenethylamine iodine solution was then spin-coated onto the surface of the PTAA hole transport layer at a spin speed of 5000 rpm for 30 s, followed by annealing at 100 °C for 5 min to obtain the phenethylamine iodine modified layer.

[0068] A mixed solution of CsI, MABr, FAI, PbI2 and PbBr2 is coated onto the surface of the interface layer to obtain a mixed solution layer of CsI, MABr, FAI, PbI2 and PbBr2. The mixed solution layer of CsI, MABr, FAI, PbI2 and PbBr2 is then annealed to obtain the perovskite layer.

[0069] In this invention, the solvent in the mixed solution of CsI, MABr, FAI, PbI2, and PbBr2 is preferably a blend of DMF and DMSO (DMF:DMSO = 4:1). The preferred concentrations of CsI, MABr, FAI, PbI2, and PbBr2 in the mixed solution are 26.1 mg / mL, 24.6 mg / mL, 283.0 mg / mL, 793.8 mg / mL, and 111.8 mg / mL. The mixture is stirred at 70°C for 2-3 hours with a magnetic stirrer. The coating is preferably spin-coating, with the spin-coating speed preferably 2000 rpm × 10 s in the first step and 6000 rpm × 30 s in the second step. 100 μL of the anti-solvent chlorobenzene is added dropwise at the 15th second of the second step. The preferred annealing temperature is 100°C, and the preferred annealing time is 30 minutes.

[0070] 3. For wide-bandgap perovskite solar cells (FA) with a bandgap of 1.78 eV. 0.83 Cs 0.17 Pb(I 0.6 Br 0.4 3) The perovskite layer preparation process is as follows:

[0071] Self-assembled monolayers of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) and [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2-PACz) were dissolved in isopropanol at a mass ratio of 1:1 to obtain a hole transport layer precursor solution with a mass concentration of 0.5 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 3000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 100 °C for 10 min to obtain the hole transport layer.

[0072] A mixed solution of CsI, FAI, PbI2 and PbBr2 is coated onto the surface of the interface layer to obtain a mixed solution layer of CsI, FAI, PbI2 and PbBr2. The mixed solution layer of CsI, FAI, PbI2 and PbBr2 is then annealed to obtain the perovskite layer.

[0073] In this invention, the solvent in the mixed solution of CsI, MABr, FAI, PbI2 and PbBr2 is preferably a blend of DMF and DMSO (DMF:DMSO = 4:1). The concentrations of CsI, FAI, PbI2 and PbBr2 in the mixed solution are preferably 68.9 mg / mL, FAI2 22.7 mg / mL, PbI2 287.65 mg / mL, and PbBr2 343.5 mg / mL. The coating is preferably spin coating, and the spin coating speed is preferably 1000 rpm × 10 s in the first step and 5000 rpm × 40 s in the second step. 300 μL of the anti-solvent anisole is added dropwise at the 35th second of the second step. The annealing temperature is preferably 100℃, and the annealing time is preferably 30 min.

[0074] After obtaining the aforementioned narrow-bandgap, medium-bandgap, and wide-bandgap perovskite layers, an electron transport layer was subsequently fabricated on the perovskite layers, and C was deposited by vacuum deposition. 60 Electron transport layer, 25-50 nm thick, with a deposition rate of [missing information]. No thermal annealing is required after deposition to obtain C. 60 Electron transport layer;

[0075] The ytterbium metal was placed at the evaporation source position in the evaporation chamber, and the pressure in the coating chamber was allowed to drop to 4 × 10⁻⁶. -4 After Pa, the evaporation source temperature was adjusted to begin depositing ytterbium metal. When the film thickness gauge data showed that the deposition rate was... Then, the substrate rotation speed was set to 18 r / min, the substrate baffle was opened, and a ytterbium metal with a thickness of 1.5 nm was deposited by vapor deposition. Then the substrate baffle was closed. Since ytterbium metal is extremely easy to oxidize, it may be partially or completely converted into ytterbium oxide during the vapor deposition process, thus obtaining an interface buffer layer.

[0076] A copper electrode is vacuum-deposited onto the surface of the interface buffer layer to obtain a perovskite solar cell.

[0077] Comparative Example 1

[0078] The ITO transparent conductive substrate was cleaned by ultrasonic cleaning for 15 minutes each using glass cleaner, deionized water, acetone, and isopropanol.

[0079] A self-assembled monolayer of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) was dissolved in isopropanol to obtain a hole transport layer precursor solution with a mass concentration of 0.5 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 3000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 100 °C for 10 min to obtain the hole transport layer.

[0080] 1. For narrow bandgap perovskite solar cells with a bandgap of 1.55 eV, the perovskite layer fabrication process is as follows:

[0081] A self-assembled monolayer of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) was dissolved in isopropanol to obtain a hole transport layer precursor solution with a mass concentration of 0.5 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 3000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 100 °C for 10 min to obtain the hole transport layer.

[0082] A mixed solution of CsI, RbI, MABr, FAI, PbI2 and PbBr2 is coated onto the surface of the interface layer to obtain a mixed solution layer of CsI, RbI, MABr, FAI, PbI2 and PbBr2. The mixed solution layer of CsI, RbI, MABr, FAI, PbI2 and PbBr2 is then annealed to obtain the perovskite layer.

[0083] In this invention, the solvent in the mixed solution of CsI, RbI, MABr, FAI, PbI2 and PbBr2 is preferably a blend of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (DMF:DMSO = 4:1). The preferred concentrations of CsI, RbI, MABr, FAI, PbI2 and PbBr2 in the mixed solution are 19.5 mg / mL, 15.9 mg / mL, 8.4 mg / mL, 19.5 mg / mL, 656.9 mg / mL, and 27.5 mg / mL. The coating is preferably spin coating, and the spin coating speed is preferably 1000 rpm × 10 s in the first step and 3000 rpm × 30 s in the second step. 150 μL of anti-solvent chlorobenzene is added dropwise in the 15th second of the second step. The annealing temperature is preferably 100℃ and the annealing holding time is preferably 10 min.

[0084] 2. For a medium-bandgap perovskite solar cell with a bandgap of 1.61 eV, the perovskite layer fabrication process is as follows:

[0085] Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was dissolved in toluene to obtain a hole transport layer precursor solution with a mass concentration of 2 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 5000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 120 °C for 10 min to obtain the hole transport layer.

[0086] Phenethylamine iodine was dissolved in isopropanol at a concentration of 10 mg / mL and shaken thoroughly to ensure complete dissolution. The phenethylamine iodine solution was then spin-coated onto the surface of the PTAA hole transport layer at a spin speed of 5000 rpm for 30 s, followed by annealing at 100 °C for 5 min to obtain the phenethylamine iodine modified layer.

[0087] A mixed solution of CsI, MABr, FAI, PbI2 and PbBr2 is coated onto the surface of the interface layer to obtain a mixed solution layer of CsI, MABr, FAI, PbI2 and PbBr2. The mixed solution layer of CsI, MABr, FAI, PbI2 and PbBr2 is then annealed to obtain the perovskite layer.

[0088] In this invention, the solvent in the mixed solution of CsI, MABr, FAI, PbI2, and PbBr2 is preferably a blend of DMF and DMSO (DMF:DMSO = 4:1). The preferred concentrations of CsI, MABr, FAI, PbI2, and PbBr2 in the mixed solution are 26.1 mg / mL, 24.6 mg / mL, 283.0 mg / mL, 793.8 mg / mL, and 111.8 mg / mL. The mixture is stirred at 70°C for 2-3 hours with a magnetic stirrer. The coating is preferably spin-coating, with the spin-coating speed preferably 2000 rpm × 10 s in the first step and 6000 rpm × 30 s in the second step. 100 μL of the anti-solvent chlorobenzene is added dropwise at the 15th second of the second step. The preferred annealing temperature is 100°C, and the preferred annealing time is 30 minutes.

[0089] 3. For a wide bandgap perovskite solar cell with a bandgap of 1.78 eV, the perovskite layer fabrication process is as follows:

[0090] Self-assembled monolayers of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) and [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2-PACz) were dissolved in isopropanol at a mass ratio of 1:1 to obtain a hole transport layer precursor solution with a mass concentration of 0.5 mg / mL. The hole transport layer precursor solution was spin-coated onto the surface of an ITO conductive substrate at a spin speed of 3000 rpm for 30 s to obtain a hole transport layer precursor solution layer. Subsequently, it was annealed at 100 °C for 10 min to obtain the hole transport layer.

[0091] A mixed solution of CsI, FAI, PbI2 and PbBr2 is coated onto the surface of the interface layer to obtain a mixed solution layer of CsI, FAI, PbI2 and PbBr2. The mixed solution layer of CsI, FAI, PbI2 and PbBr2 is then annealed to obtain the perovskite layer.

[0092] In this invention, the solvent in the mixed solution of CsI, MABr, FAI, PbI2 and PbBr2 is preferably a blend of DMF and DMSO (DMF:DMSO = 4:1). The concentrations of CsI, FAI, PbI2 and PbBr2 in the mixed solution are preferably 68.9 mg / mL, FAI2 22.7 mg / mL, PbI2 287.65 mg / mL, and PbBr2 343.5 mg / mL. The coating is preferably spin coating, and the spin coating speed is preferably 1000 rpm × 10 s in the first step and 5000 rpm × 40 s in the second step. 300 μL of the anti-solvent anisole is added dropwise at the 35th second of the second step. The annealing temperature is preferably 100℃, and the annealing time is preferably 30 min.

[0093] After obtaining the aforementioned narrow-bandgap, medium-bandgap, and wide-bandgap perovskite layers, an electron transport layer was subsequently fabricated on the perovskite layers, and C was deposited by vacuum deposition. 60 Electron transport layer, 25-50 nm thick, with a deposition rate of [missing information]. No thermal annealing is required after deposition to obtain C. 60 Electron transport layer;

[0094] Subsequently, a BCP interface buffer layer is prepared, which can be prepared by solution method or vacuum evaporation. For the solution method, BCP is first dissolved in ethanol to obtain an interface buffer layer precursor solution with a mass concentration of 1 mg / mL. This precursor solution is then spin-coated onto the electron transport layer surface at a speed of 5000 rpm for 30 seconds, resulting in the copper bath interface buffer layer. For the vacuum evaporation method, the chamber pressure is 4 × 10⁻⁶. -4 The PA thickness is 5-10 nm, and the evaporation rate is... No thermal annealing is required after deposition.

[0095] Finally, copper electrodes were vacuum-deposited onto the surface of the copper bath interface buffer layer to obtain a perovskite solar cell.

[0096] Test Example 1

[0097] The perovskite solar cells prepared in Example 1 and Comparative Example 1 were subjected to aging experiments. The aging conditions were: outdoor heating at 85℃ for 10 hours, with an outdoor humidity of 50–60% RH. The test results are as follows: Figure 1 As shown, by Figure 1 It can be seen that in Comparative Example 1, when copper bath is used as an interface buffer layer, the electrode aging is obvious at 85℃, which seriously limits the long-term stability of the device.

[0098] Test Example 2

[0099] Figure 2 Table 1 shows the photoelectric conversion efficiency, device performance statistical distribution, steady-state output, and external quantum efficiency curves of the narrow-bandgap, medium-bandgap, and wide-bandgap perovskite solar cells prepared in Example 1 of this invention. The optimal performance devices are listed in Table 1. Figure 2 As shown in Table 1, the ytterbium oxide interface buffer layer has excellent versatility and can help various perovskite systems achieve high photoelectric conversion performance. For a narrow bandgap perovskite solar cell with a bandgap of 1.56 eV, we achieved an ultra-high photoelectric conversion performance of 24.6%.

[0100] Table 1 shows the performance parameters of the perovskite solar cells prepared in Example 1.

[0101]

[0102]

[0103] The perovskite solar cells prepared in Example 1 and Comparative Example 1 were subjected to stability testing. The test conditions were: under light-shielded conditions, in a nitrogen atmosphere, and heated to 85°C. The power conversion efficiency (PCE) of the perovskite solar cells prepared in Example 1 and Comparative Example 1 as a function of time is shown below. Figure 3 As shown, by Figure 2 As can be seen from a and 2b, at the same time, the power conversion efficiency decay of the wide-bandgap and narrow-bandgap perovskite solar cells prepared in Example 1 of the present invention is significantly smaller than that of Comparative Example 1. At the same time, we can also find that due to the thermal instability of BCP, the devices using BCP as an interface buffer layer in the initial testing stage have a significant trend of device performance degradation. Figure 2 c represents the maximum power point output curve of a narrow bandgap perovskite solar cell using ytterbium oxide as an interface buffer layer under continuous LED illumination. We can see that after 1000 hours of continuous monitoring, the device performance still maintains 98% of its initial performance.

[0104] The perovskite solar cell provided by this invention uses ytterbium oxide as an interface buffer layer without compromising the device's photoelectric conversion performance. The ultrathin ytterbium metal transforms into ytterbium oxide after evaporation. Ytterbium oxide has a low work function, which facilitates the formation of ohmic contacts between the electron transport layer and the metal electrodes, reducing carrier recombination at the interface. This invention achieves an ultra-high photoelectric conversion performance of nearly 25% using ytterbium oxide as an interface buffer layer. External quantum efficiency curve testing also verifies the reliability of the short-circuit current density in JV testing (e.g., ...). Figure 2 (Test results).

[0105] Meanwhile, the perovskite solar cell provided by this invention uses inorganic ytterbium oxide as an interface buffer layer, which significantly improves device stability, especially thermal stability, while achieving high photoelectric conversion efficiency. Existing organic BCP buffer layers are unstable under thermal conditions, easily agglomerating or degrading, leading to a decrease in device stability; using a stable inorganic ytterbium oxide interface buffer layer can prevent the diffusion of electrode metal atoms and simultaneously suppress the oxidation of the metal electrode (e.g., ...). Figure 1 The test results show that the interface stability is greatly improved, resulting in highly stable perovskite solar cells (such as...). Figure 3 (Test results);

[0106] Finally, the perovskite solar cell fabrication method provided by this invention is simple. It eliminates the need for complex thin-film deposition techniques such as magnetron sputtering and atomic layer deposition; thin-film deposition can be achieved through simple thermal evaporation, which is crucial for the large-scale production of perovskite solar cells.

[0107] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A perovskite solar cell, said perovskite solar cell comprising an interface buffer layer, characterized in that, When the perovskite solar cell is a formal perovskite solar cell without an electron transport layer structure, the interface buffer layer is located between the transparent conductive substrate and the perovskite layer. When the perovskite solar cell is a perovskite solar cell with a formal electron transport layer structure, the interface buffer layer is located between the electron transport layer and the perovskite layer. The preparation of the interface buffer layer in the perovskite solar cell includes: using ytterbium metal as an evaporation source, the interface buffer layer is obtained by vacuum evaporation followed by oxidation; the thickness of the interface buffer layer is 0.5~10 nm; the interface buffer layer is a material containing ytterbium.

2. The perovskite solar cell according to claim 1, characterized in that, The chemical composition of the interface buffer layer includes ytterbium oxide.

3. The perovskite solar cell according to claim 2, characterized in that, The chemical composition of the interface buffer layer also includes ytterbium.

4. The perovskite solar cell according to any one of claims 1 to 3, characterized in that, The electron transport layer is chemically composed of carbon compounds.

5. The perovskite solar cell according to claim 4, characterized in that, The carbon compound includes [6,6]-phenyl-C61-butyrate isomethyl ester or [6,6]-phenyl-C71-butyrate isomethyl ester.

6. The perovskite solar cell according to any one of claims 1 to 3, characterized in that, The electron transport layer has a chemical composition of C. 60 .

7. The perovskite solar cell according to claim 1, characterized in that, The chemical composition of the hole transport layer in the formal electron-transport-free perovskite solar cell includes poly(4-phenyl)(2,4,6-trimethylphenyl)amine, poly[bis(4-phenyl)(4-butylphenyl)amine], poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), nickel oxide, (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, or [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

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