A trans-perovskite battery with modified C60 as an electron transport layer and a preparation method thereof

Abstract

The application relates to a trans-perovskite battery with modified C60 as an electron transport layer and a preparation method, the trans-perovskite battery comprising a substrate, a hole transport layer, a perovskite layer, an electron transport layer and a top electrode arranged in sequence, the perovskite layer generates free electrons and holes in a photoexcited state, the free electrons enter the electron transport layer, and the holes enter the hole transport layer, the electron transport layer adopts a modified C60 material, the electron mobility and film forming quality are improved, the preparation method of the trans-perovskite battery, uniform dispersion distribution of silver in a C60 film is realized through a double-source co-evaporation process, high-efficiency electron transport channels are constructed by utilizing the excellent conductivity of silver, meanwhile, the film compactness is improved by filling the intermolecular gaps of C60 with silver atoms, so that the electron transport efficiency and the device stability are simultaneously improved.

Description

Technical Field

[0001] This invention relates to an inverted perovskite solar cell with modified C60 as the electron transport layer and its preparation method, belonging to the field of photovoltaics. Background Technology

[0002] Perovskite solar cells have become a research hotspot in the photovoltaic field due to their advantages such as high photoelectric conversion efficiency, simple fabrication process, and low cost. Among them, inverted (pin) perovskite solar cells have attracted widespread attention due to their advantages such as low fabrication temperature, good process compatibility, and flexibility. Inverted perovskite solar cells include single-junction cells as well as tandem cells such as perovskite / crystalline silicon tandem cells and all-perovskite tandem cells. However, the long-term stability and large-area fabrication compatibility of inverted perovskite cells still need to be improved.

[0003] C60 (fullerene) is the most widely used electron transport material in the field of inverted perovskite solar cells. Whether in single-junction or tandem cells, it possesses advantages such as high electron mobility, excellent thin-film formation properties, and high visible light transmittance, enabling efficient extraction and transport of photogenerated electrons from the perovskite light-absorbing layer. However, C60 films have low intrinsic conductivity and also suffer from defects such as high interfacial contact resistance, numerous pores, and poor density. During cell operation, carrier accumulation at the interface is prone to occur, leading to interfacial carrier recombination losses, ultimately limiting the photoelectric conversion efficiency and long-term stability of inverted perovskite solar cells. Therefore, there is an urgent need to develop novel electron transport layer materials that combine high electron mobility and excellent film formation quality to improve cell efficiency. Summary of the Invention

[0004] To improve the efficiency of inverted perovskite solar cells, this invention provides an inverted perovskite solar cell with modified C60 as the electron transport layer. In this cell, modified C60 is used as the electron transport layer to improve electron mobility and film quality. The invention also provides a method for preparing this inverted perovskite solar cell. A dual-source co-evaporation process is used to achieve uniform dispersion of silver in the C60 film. The excellent conductivity of silver is used to construct an efficient electron transport pathway. At the same time, the silver atoms fill the gaps between C60 molecules to improve the film density, thereby simultaneously improving electron transport efficiency and device stability.

[0005] The technical solution adopted in this invention is as follows: an inverted perovskite solar cell with modified C60 as the electron transport layer, comprising a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a top electrode arranged sequentially. The perovskite layer generates free electrons and holes under photoexcitation. The free electrons enter the electron transport layer, and the holes enter the hole transport layer. The electron transport layer is made of modified C60 material, which is formed with C60 as the main material and silver as the dopant element.

[0006] Preferably, the modified C60 material is formed by co-evaporation of C60 and metallic silver, and the ratio of the evaporation rate of C60 to the evaporation rate of Ag during co-evaporation is 40:(1~8).

[0007] Preferably, in the modified C60 material, silver particles are dispersed in the intermolecule gaps of C60, with a size of 2-3 nm, and the thickness of the electron transport layer formed is 10-20 nm.

[0008] Preferably, the perovskite layer material is formamidinium lead iodine or formamidinium lead iodine bromine, and the hole transport layer material is MeO-2PACz or nickel oxide.

[0009] Preferably, a SnO2 layer is disposed between the electron transport layer and the top electrode, and the total thickness of the electron transport layer and the SnO2 layer is 25~50 nm. This thickness can reduce the optical absorption loss of C60 while ensuring electrical functionality.

[0010] This invention also provides a method for preparing an inverse perovskite solar cell, comprising the following steps: S01 Obtain the substrate; S02 deposits a hole transport layer on a substrate, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S03 deposits a perovskite layer on the hole transport layer, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S04 deposits an electron transport layer on the perovskite layer, the electron transport layer being formed by co-evaporation of C60 and metallic silver; S05 is used to fabricate the top electrode on the electron transport layer.

[0011] Preferably, the electron transport layer is formed by co-evaporation of C60 and metallic silver at a deposition rate of 40:(1~8), with a vacuum degree of 5×10⁻⁶ during co-evaporation. -4 Below Pa.

[0012] Preferably, a SnO2 layer is first deposited on the electron transport layer, and then step S05 is performed. The SnO2 layer is prepared by atomic layer deposition, using tetra(dimethylamino)tin as the tin source and deionized water as the oxygen source. The deposition temperature is 110~130℃ and the deposition thickness is 15~30nm.

[0013] As a preferred method, the hole transport layer is prepared by spin-coating a MeO-2PACz solution onto the surface of the intermediate composite linker layer at a spin-coating speed of 3000~4000 rpm and a spin-coating time of 30~45 s, followed by annealing at 120℃ for 10 min.

[0014] Preferably, the perovskite layer is prepared using a stepwise spin-coating method, firstly by spin-coating at 2000 rpm for 20 s, followed by spin-coating at 5000 rpm for 30 s, with ethyl acetate added dropwise as an anti-solvent 10 s before the end of the second spin-coating step, and finally annealed at 110°C for 15 min. The present invention also provides a method for preparing an inverse perovskite solar cell, comprising the following steps: S01 Obtain the substrate; S02 deposits a hole transport layer on a substrate, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S03 deposits a perovskite layer on the hole transport layer, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S04 deposits an electron transport layer on the perovskite layer, the electron transport layer being formed by co-evaporation of C60 and metallic silver; S05 is used to fabricate the top electrode on the electron transport layer.

[0015] Preferably, the electron transport layer is co-evaporated with C60 and metallic silver at a evaporation rate of 40:(1~8), and the vacuum degree during co-evaporation is below 5×10-4 Pa.

[0016] Preferably, a SnO2 layer is first deposited on the electron transport layer, and then step S05 is performed. The SnO2 layer is prepared by atomic layer deposition, using tetra(dimethylamino)tin as the tin source and deionized water as the oxygen source. The deposition temperature is 110~130℃ and the deposition thickness is 15~30nm.

[0017] As a preferred method, the hole transport layer is prepared by spin-coating a MeO-2PACz solution onto the surface of the intermediate composite linker layer at a spin-coating speed of 3000~4000 rpm and a spin-coating time of 30~45 s, followed by annealing at 110~130℃.

[0018] Preferably, the perovskite layer is prepared by a stepwise spin coating method, firstly by spin coating at 1500~2500 rpm for 10~30 s, then by spin coating at 4500~5500 rpm for 20~40 s, and then by adding ethyl acetate as an anti-solvent 5~15 s before the end of the second spin coating step, and finally by annealing at 100~120℃.

[0019] The beneficial effects of this invention include: (1) By using silver doping, silver atoms are embedded in the interstices of C60 molecules in a dispersed state to form a continuous metallic conductive network, providing a fast transport channel for electrons and significantly reducing the interfacial transport impedance. The Fermi level of the silver nanoparticles matches well with the LUMO level of C60, allowing electrons to tunnel from the excited state of C60 to the silver conductive network and then quickly transport to the external circuit, avoiding the slow long-distance transport of electrons in the C60 thin film.

[0020] (2) This invention effectively compresses the molecular gaps by filling the C60 molecular gaps with silver atoms, thereby reducing porosity and improving the density of the film. At the same time, the uniform distribution of silver atoms on the film surface can smooth the surface morphology and reduce surface roughness. The dense and smooth film can reduce the density of interface defect states and reduce the non-radiative recombination rate. It can also effectively block the penetration of external water vapor and oxygen, thus slowing down the aging and failure of perovskite materials.

[0021] (3) Silver nanoparticles exhibit surface plasmon resonance. When incident light interacts with silver nanoparticles, it excites local surface plasmon resonance, forming an enhanced local electric field around the particles, which promotes the generation of photogenerated carriers in the perovskite light absorption layer. The absorbance of the C60 film is improved after silver doping, with the average absorbance of visible light increasing by 7.5%, which increases the number of photogenerated carriers and thus improves the short-circuit current density.

[0022] (4) The present invention adopts a dual-source vacuum co-evaporation process, which can fix the C60 evaporation rate and achieve precise control of the doping amount by adjusting the Ag evaporation rate. This process avoids the problems of concentration fluctuation in solution doping and energy unevenness in ion implantation. The process is simple, has good repeatability, and is easy to scale up for production.

[0023] (5) This invention, through the material and process design of the hole transport layer, perovskite layer, and hole blocking layer, forms a highly efficient and complete charge separation-transport-collection system with the electron transport layer. The components include a silver-doped C60 electron transport layer, a perovskite layer, MeO-2PACz, or NiO. X The hole transport layer forms a good energy level gradient, which promotes charge separation; it forms a bilayer structure of electron transport and hole blocking with the SnO2 layer, which reduces interfacial recombination; and it forms a tight interfacial contact with the perovskite light absorption layer, which reduces interfacial defects, thereby significantly improving the device efficiency and stability. Attached Figure Description

[0024] Figure 1 Photoelectric performance diagrams of the embodiments and comparative examples in this invention; Figure 2 SEM image of the electron transport layer in the comparative example, with the short line in the image representing the 200nm scale; Figure 3 SEM image of the electron transport layer in Example 2, with the short line representing a 200nm scale. Detailed Implementation

[0025] The present invention is described in more detail below, but it should not be construed as limiting the scope of protection of the invention to the following description. Unless otherwise specified, any range described in the present invention includes end values, any values ​​between end values, and any sub-ranges formed by end values ​​or any values ​​between end values. There are no particular limitations on the purity of any raw materials used in the present invention; however, analytical grade materials are preferred. The sources and abbreviations of all raw materials used in the present invention are conventional sources and abbreviations in the art, and are clearly understood within the scope of their relevant uses. Those skilled in the art can obtain them from commercially available sources or prepare them using conventional methods based on the abbreviations and corresponding uses.

[0026] "At least one" means one or more, while "more" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0027] Perovskite solar cells include the standard pin-type structure and the inverted nip-type structure. The inverted perovskite solar cell of this invention comprises a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a top electrode, stacked sequentially. This sequential stacking only indicates a positional relationship and does not limit whether they are in contact; they can be directly contacted or stacked through intermediate layers, such as an interface modification layer connecting the hole transport layer and the perovskite layer. The perovskite layer, acting as a light-absorbing layer, generates free electrons and holes under photoexcitation. Free electrons enter the electron transport layer and are conducted to the top electrode, while holes enter the hole transport layer and are conducted to the bottom electrode. The electron transport layer uses a modified C60 material, which is formed with C60 as the main material and silver as a dopant. Silver is dispersed in the intermolecule gaps of C60. C60 molecules have a hollow cage-like structure, with molecules bound by van der Waals forces. After forming the thin film, a large number of intermolecule gaps exist, resulting in high porosity and insufficient density of the film. Silver atoms are dispersedly embedded in the interstices of C60 molecules, filling these gaps, reducing film porosity, and increasing density. Furthermore, the silver atoms form a conductive network, creating efficient electron transport channels and significantly reducing interfacial transport impedance. In addition, the surface plasmon resonance effect of silver nanoparticles enhances the local electric field, promoting the generation and separation of photogenerated carriers and improving light absorption efficiency.

[0028] The electron transport layer was prepared using a dual-source vacuum co-evaporation process. During co-evaporation, the ratio of the C60 deposition rate to the Ag deposition rate was 40:(1~8), preferably with the C60 deposition rate fixed at 0.4 Å / s and the Ag deposition rate at 0.01~0.08 Å / s. This deposition rate ratio directly determines the silver doping concentration, thus affecting the microstructure and photoelectric properties of the film. At this deposition rate, silver is uniformly distributed in a dispersed state among the C60 molecules, forming a complete conductive network without excessive aggregation, balancing the film density and carrier transport requirements. When the Ag deposition rate is lower than this value, the silver content is low, the formed conductive network is not complete, and the improvement in electron transport efficiency is limited. When the Ag deposition rate is higher than this value, the silver content is excessive, and some silver atoms aggregate to form clusters, creating defect recombination centers, which increases carrier recombination loss and leads to performance degradation. Therefore, by precisely controlling the deposition rate ratio, precise control of the doping amount can be achieved, improving battery performance. As a preferred option, the C60 to Ag ratio is 10:1, and silver is uniformly distributed in the C60 lattice interstices in a dispersed state without agglomeration and precipitation, resulting in the best film density, the lowest interfacial transport impedance, and the highest photoelectric conversion efficiency.

[0029] Preferably, the thickness of the electron transport layer is 10-20 nm. This thickness ensures efficient electron transport while maintaining high visible light transmittance, avoiding absorption loss of incident light due to an excessively thick electron transport layer. The silver particles doped with C60 have a size of 2-3 nm. Within this size range, molecular-level composites can be achieved between silver and C60, rather than physical-level mixing.

[0030] Perovskite materials are represented by the general formula ABX3, where A is at least one monovalent cation, such as MA. + FA + Cs + 、Rb + In this case, B is at least one divalent cation, such as Ca. 2+ Pb 2+ Sn 2+ Cu 2+ And X is at least one anion, such as I - ,Br - Cl - F - SCN -When the perovskite includes more than one type of A cation, different A cations can be distributed at the A sites in an ordered or disordered manner. When the perovskite includes more than one type of B cation, different B cations can be distributed at the B sites in an ordered or disordered manner. When the perovskite includes more than one type of X anion, different X anions can be distributed at the X sites in an ordered or disordered manner. In this invention, the perovskite material for the perovskite battery is preferably formamidinium lead iodide or formamidinium lead iodide bromide, i.e., A is FA. + B is Pb 2+ C is I - and / or Br - The hole transport layer material is either MeO-2PACz or nickel oxide. Silver doping reduces the surface roughness of the C60 film, leading to a tighter interfacial contact with the perovskite layer, reducing interfacial porosity and defect state density, and lowering the nonradiative recombination rate. MeO-2PACz, as a self-assembled monolayer hole transport material, exhibits good energy level matching and interfacial contact characteristics with the perovskite material; nickel oxide, as an inorganic hole transport material, is beneficial for improving the chemical and thermal stability of the device. The silver-doped C60 electron transport layer forms a good energy level gradient with the aforementioned perovskite and hole transport materials, promoting efficient injection of photogenerated electrons from the perovskite light-absorbing layer to the electron transport layer, while simultaneously blocking the reverse transport of holes and reducing interfacial recombination. To further enhance electron transport capability, this invention preferably places a SnO2 layer between the modified C60 electron transport layer and the top electrode. This forms a 25-50 nm dual electron transport layer, where the modified C60 electron transport layer efficiently transports electrons, while the SnO2 layer transports electrons and blocks holes, jointly improving charge separation efficiency and device stability. The SnO2 layer is preferably formed using atomic layer deposition (ALD). ALD produces a dense and uniform SnO2 film that effectively blocks the penetration of external moisture and oxygen, protecting the underlying electron transport layer and perovskite layer, further enhancing device stability.

[0031] The inverted perovskite solar cell in this invention can be a single junction or a stacked structure, wherein the stacked structure includes, but is not limited to, silicon-calcium stacked structure and calcium-calcium stacked structure. In the stacked solar cell, the bottom cell serves as the substrate and the top cell is an inverted perovskite solar cell. It is preferably applicable to silicon-calcium stacked solar cells. The solar cell includes an HJT crystalline silicon solar cell as the substrate, a hole transport layer, a perovskite layer, an electron transport layer and a top electrode. An intermediate connecting layer is provided between the substrate and the hole transport layer, which can be a transparent conductive layer or a tunneling layer.

[0032] This invention also provides a method for fabricating an inverted perovskite solar cell, comprising the step of fabricating the aforementioned silver-doped C60 electron transport layer. The method further includes: fabricating a hole transport layer and a perovskite light-absorbing layer below the electron transport layer; fabricating a SnO2 hole-blocking layer above the electron transport layer; and fabricating a top electrode above the SnO2 hole-blocking layer.

[0033] Preferably, the hole transport layer is prepared by spin-coating a MeO-2PACz solution onto the surface of the intermediate composite linker layer at a spin-coating speed of 3000-4000 rpm for 30-45 s, followed by annealing at 120°C for 10 min. The annealing treatment allows MeO-2PACz molecules to self-assemble on the substrate surface to form a dense and ordered monolayer, optimizing interfacial contact and energy level matching.

[0034] Preferably, the perovskite light-absorbing layer is prepared by a stepwise spin-coating method: first, spin-coating at 2000 rpm for 20 seconds, followed by spin-coating at 5000 rpm for 30 seconds, and then adding ethyl acetate as an anti-solvent 10 seconds before the end of the second spin-coating step, and finally annealing at 110°C for 15 minutes. The stepwise spin-coating combined with anti-solvent extraction can promote rapid nucleation and crystallization of perovskite, forming a dense and smooth light-absorbing layer.

[0035] The inverse perovskite solar cell of this invention can be prepared by the following method: S01 Obtain the substrate; S02 deposits a hole transport layer on a substrate, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S03 deposits a perovskite layer on the hole transport layer, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S04 deposits an electron transport layer on the perovskite layer, wherein the electron transport layer is formed by co-evaporation of C60 and metallic silver, and the ratio of the evaporation rate of C60 to the evaporation rate of Ag during co-evaporation is 40:(1~8). S05 is used to fabricate the top electrode on the electron transport layer.

[0036] In one embodiment, the hole transport layer is prepared by spin-coating a MeO-2PACz solution onto the surface of the intermediate composite connecting layer at a spin-coating speed of 3000-4000 rpm for 30-45 s, followed by annealing at 120°C for 10 min. Annealing allows MeO-2PACz molecules to self-assemble on the substrate surface to form a dense and ordered monolayer, optimizing interfacial contact and energy level matching. The perovskite layer is prepared by a stepwise spin-coating method: first, spin-coating at 2000 rpm for 20 s, followed by spin-coating at 5000 rpm for 30 s, with ethyl acetate added as an antisolvent 10 s before the end of the second spin-coating step, and finally annealing at 110°C for 15 min. Stepwise spin-coating combined with antisolvent extraction promotes rapid nucleation and crystallization of the perovskite, forming a dense and smooth light-absorbing layer. The electron transport layer is prepared by placing C60 raw material and Ag in two evaporation sources of a vacuum evaporation equipment; controlling the base vacuum at 5 × 10⁻⁶. -4 The pressure was kept below 1000 Pa to avoid contamination of the film by impurities such as oxygen and water vapor during the evaporation process. The C60 evaporation rate was fixed at 0.4 Å / s, and the Ag evaporation rate was adjusted within the range of 0.01~0.08 Å / s. A silver-doped C60 electron transport layer was co-evaporated and deposited on the substrate surface, with a thickness controlled at 10~20 nm. The core advantage of the dual-source co-evaporation process is that C60 and Ag evaporate and deposit simultaneously, and silver atoms are embedded into the molecular gaps in real time during the growth of the C60 film, achieving uniform doping at the atomic level and avoiding problems such as inhomogeneity and interface damage commonly encountered in post-processing doping. The SnO2 layer was prepared using atomic layer deposition, with tetra(dimethylamino)tin as the tin source and deionized water as the oxygen source, at a deposition temperature of 110~130℃, and a deposition thickness of 20 nm. The SnO2 layer can effectively block the transport of holes to the top electrode, reduce interfacial recombination, and protect the underlying perovskite and modified C60 electron transport layer from environmental corrosion. The top electrode is deposited with silver using a vacuum thermal evaporation method, with a thickness of 80-120 nm, and the evaporation vacuum degree is maintained at 7 × 10⁻⁶. -4 Below Pa. Silver electrodes have excellent conductivity and reflectivity, which can effectively collect photogenerated electrons and reflect unabsorbed photons, thereby improving light utilization.

[0037] The following detailed description uses specific embodiments as examples. Example 1

[0038] The preparation method of the inverse calcium-titanium battery in this embodiment is as follows: S01 Obtaining the substrate. In this embodiment, an HJT silicon wafer with dimensions of 2.5cm × 2.5cm is used as the silicon substrate. The substrate is a crystalline silicon cell with a pre-fabricated back silver electrode.

[0039] The hole transport layer was prepared using SO2. MeO-2PACz was used as the hole transport layer. The specific steps were as follows: 1 mg of MeO-2PACz was mixed with 1 mL of ethanol solution to obtain a 1 mg / mL MeO-2PACz solution. After filtering to remove large particles, the solution was spin-coated onto a silicon wafer at a spin rate of 3300 rpm for 30 s. The wafer was then annealed at 120 °C for 10 min to obtain a MeO-2PACz hole transport layer approximately 3 nm thick.

[0040] The preparation of the SO3 perovskite layer specifically includes: Preparation of precursor solution: The perovskite precursor solution was prepared by mixing formamidine hydroiodide (FAI) and lead iodide (PbI2) in a molar ratio of 1:1 and dissolving them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1. The mixture was shaken and stirred at room temperature for 12 h to obtain a clear solution with a concentration of 1.5 M.

[0041] (2) Stepwise spin coating: First, spin coating was performed at 2000 rpm for 20 s, then the speed was increased to 5000 rpm for another 30 s, and ethyl acetate (EA) was added as an antisolvent 10 s before the end of the second step. The film was then annealed at 110 °C for 15 min to form a perovskite layer.

[0042] The preparation of the SO4 modified layer includes the following steps: Preparation of ethylenediamine dihydroiodate (EDAI2) solution: Dissolve 0.5 mg of EDAI2 in 1 mL of isopropanol, shake and stir to form an isopropanol solution of 0.5 mg / mL EDAI2, and filter the solution using a 0.45 μm filter cartridge to remove larger particles, thus obtaining the EDAI2 solution.

[0043] (2) Spin-coat the EDAI2 solution onto the perovskite layer at a speed of 3000 rpm for 30 s, and then anneal it in a nitrogen atmosphere at 100 °C for 5 minutes to form a modified layer with a thickness of about 3 nm.

[0044] Preparation of S05 modified C60 electron transport layer. A vacuum evaporation apparatus was used, with C60 and Ag co-doped. The evaporation rate of C60 was set to 0.4 Å / s, and the evaporation rate of Ag to 0.02 Å / s, with a rate ratio of 20:1. The vacuum degree of the evaporation chamber was 5 × 10⁻⁶. -4 Below Pa, the thickness of the modified C60 electron transport layer is controlled to be 15 nm.

[0045] Preparation of the S06 SnO2 layer. An atomic layer deposition process was used, with tetra(dimethylamino)tin as the tin source and deionized water as the oxygen source, to prepare the layer on the surface of the electron transport layer. The deposition temperature was 120℃, and the deposition thickness was controlled to be 20 nm.

[0046] Fabrication of the S07 electrode. A 100 nm layer of silver (Ag) was deposited on the surface of the SnO2 barrier layer using thermal evaporation as the electrode. The vacuum level was maintained at 7 × 10⁻⁶ during the deposition process. -4 Below Pa.

[0047] Perovskite solar cells were fabricated. Example 2

[0048] The only difference from Example 1 is that the Ag evaporation rate in S05 is 0.04 Å / s, and the ratio of the two rates is 10:1. Example 3

[0049] The only difference from Example 1 is that the Ag evaporation rate in S05 is 0.06 Å / s, and the ratio of the two rates is 20:3. Example 4

[0050] The only difference from Example 2 is that nickel oxide (NiO) is used in SO2. x NiO serves as the hole transport layer (HTL). x The fabrication process is as follows: NiO with a thickness of 12 nm is prepared on a substrate using PVD. x The process involves 1000W, oxygen at 1 sccm, and argon at 97 sccm. After coating, the NiO is annealed in air at 200℃ for 10 minutes using a hot plate to obtain the desired NiO. x . Example 5

[0051] Compared with Example 2, the only difference is the preparation process of the perovskite layer. In this example, the preparation process of the perovskite layer is as follows: (1) FAI (formamidinium hydroiodide), PbI2 (lead iodide), and PbBr2 (lead bromide) were dissolved in a mixture of 1 mL N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) at a molar ratio of 1:0.75:0.25 to form a precursor solution, wherein the volume ratio of DMF to DMSO was 4.5:1; the solution was stirred overnight at room temperature until completely dissolved; the solution was filtered using a 0.22 μm polytetrafluoroethylene filter to remove large particles from the solution, resulting in a perovskite precursor solution with a concentration of 1.6 M.

[0052] (2) The perovskite precursor solution was spin-coated onto the hole transport layer at spin-coating speeds of 1000 rpm / 20 s / 200 rpm / s and 5000 rpm / 30 s / 1000 rpm / s. At the 10th second of spin-coating, 0.11 mL of the antisolvent chlorobenzene was added to the film. After the addition was completed within 2 seconds, spin-coating continued for a total of 50 seconds. After spin-coating, the film was annealed in nitrogen at 100 °C for 10 min. Comparative Example

[0053] The comparative example differs from Example 2 in that it was prepared using an undoped Ag process, specifically, only C60 was deposited in SO5 at a deposition rate of 0.4 Å / s, while the remaining preparation parameters remained the same as in Example 2. Pure C60 films exhibit large intermolecular gaps, high porosity, low electron transport efficiency, and high interfacial transport impedance. Performance testing

[0054] The photoelectric performance of the batteries prepared in Examples 1-5 and the comparative examples was tested, and the results are shown in Table 1.

[0055] Table 1. Photoelectric performance of the batteries in Examples 1-5 and Comparative Examples

[0056] As shown in Table 1, compared to the undoped control, all Ag-doped examples in Examples 1-3 exhibited significantly improved photoelectric performance and stability. In Example 2, the doping effect was optimal at a deposition rate ratio of 10:1, with open-circuit voltage, short-circuit current density, and fill factor all reaching their best values, resulting in a cell efficiency of 28.90%. In Example 1, the photoelectric efficiency was 27.69% at a deposition rate ratio of 20:1. In Example 3, the photoelectric efficiency was 27.94% at a deposition rate ratio of 20:3. These findings demonstrate that the deposition rate affects the film density and interfacial transport impedance, thus influencing the photoelectric efficiency.

[0057] In addition, the C60 films prepared in the comparative examples and Examples 1-3 were characterized at the microscopic level, and the results are shown in Table 2.

[0058] Table 2 Performance parameters of the electron transport layer obtained in the examples and comparative examples

[0059] The results show that the root mean square roughness of the pure C60 film in the comparative example is 4.26 nm, while the roughnesses of Examples 1, 2, and 3 are 3.15 nm, 1.92 nm, and 2.51 nm, respectively. This indicates that the molecules in the pure C60 film are bound by weak van der Waals forces, resulting in large intermolecular gaps and significant surface undulations. When silver atoms are embedded in these intermolecular gaps, they fill the pores and smooth the surface, reducing roughness. However, with excessive doping, silver atoms aggregate to form clusters, further increasing surface undulations and raising the roughness again. A dense and smooth film can reduce the density of interface defect states, lower the nonradiative recombination rate, and effectively block the penetration of external water vapor and oxygen, thus significantly improving device stability.

[0060] Absorbance tests using a UV spectrophotometer showed that the absorbance of the Ag-doped film was improved compared to pure C60, with Example 2 exhibiting the best absorption performance, showing a 7.5% increase in average visible light absorbance. The surface plasmon resonance effect of silver nanoparticles enhanced the local electric field, promoting the generation of photogenerated carriers; however, excessive doping resulted in scattering losses, causing a decrease in the increase in absorbance, and the variation pattern was consistent with the short-circuit current of the battery.

[0061] According to dark-state EIS, the interfacial transport resistances of the comparative example, Example 1, Example 2, and Example 3 are 45.3Ω, 33.5Ω, 21.5Ω, and 25.8Ω, respectively. The dispersed Ag particles construct a continuous conductive path, providing a fast transport channel for electrons and effectively reducing the interfacial transport impedance. With an appropriate doping ratio, the conductive network is intact and the impedance is low. However, with excessive doping, silver aggregates form local charge traps, which actually increase the impedance.

[0062] Table 3. XRD diffraction peak positions of electron transport layer materials in the examples and comparative examples.

[0063] XRD results showed that the pure C60 film exhibited characteristic diffraction peaks at 2θ = 10.8°, 17.7°, and 20.8°. The doped sample did not show sharp diffraction peaks for Ag, indicating that Ag is dispersed in the interstitial spaces of the C60 lattice without agglomeration. The slight shift in the characteristic peaks of C60 after doping modification confirmed that Ag was successfully incorporated into the film without disrupting the bulk C60 crystal structure.

[0064] Films were fabricated on wafers using the electron transport layer preparation methods described in Example 2 and the comparative example. Observations were performed using SEM. Figure 2 and Figure 3 As shown, from Figure 2 It can be seen that there are relatively many holes. Figure 3 Silver doping improves film quality.

[0065] In summary, this invention achieves uniform and dispersed silver doping in C60 thin films through a dual-source vacuum co-evaporation process. It leverages silver's conductivity to construct efficient electron transport channels, utilizes silver atoms to fill molecular gaps to enhance film density, and utilizes silver's plasmon resonance effect to enhance light absorption. These three factors work synergistically to significantly improve the photoelectric conversion efficiency and long-term stability of inverted silicon-calcium tandem solar cells. Furthermore, the synergistic design of the electron transport layer, hole transport layer, blocking layer, and perovskite light-absorbing layer forms a complete charge separation-transport-collection system, further enhancing device performance.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A trans-perovskite solar cell using modified C60 as the electron transport layer, characterized in that: The device comprises a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a top electrode arranged sequentially. The perovskite layer generates free electrons and holes under photoexcitation. The free electrons enter the electron transport layer, and the holes enter the hole transport layer. The electron transport layer is made of modified C60 material, which is based on C60 and doped with silver. The modified C60 material is formed by co-evaporation of C60 and metallic silver. During co-evaporation, the ratio of the evaporation rate of C60 to that of Ag is 40:(1~8).

2. The inverse perovskite solar cell according to claim 1, characterized in that: In the modified C60 material, silver particles are dispersed in the intermolecule gaps of C60, with a size of 2-3 nm, and the thickness of the electron transport layer formed is 10-20 nm.

3. The inverse perovskite solar cell according to claim 1, characterized in that: The perovskite layer material is formamidinium lead iodine or formamidinium lead iodine bromine, and the hole transport layer material is MeO-2PACz or nickel oxide.

4. The inverse perovskite solar cell according to claim 1, characterized in that: A SnO2 layer is disposed between the electron transport layer and the top electrode, and the total thickness of the electron transport layer and the SnO2 layer is 25~50nm.

5. A method for preparing an inverted perovskite solar cell with modified C60 as the electron transport layer, characterized in that: Includes the following steps: S01 Obtain the substrate; S02 deposits a hole transport layer on a substrate, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S03 deposits a perovskite layer on the hole transport layer, and the deposition method is one or a combination of solution coating, vapor deposition, and magnetron sputtering. S04 deposits an electron transport layer on the perovskite layer, the electron transport layer being formed by co-evaporation of C60 and metallic silver; S05 is used to fabricate the top electrode on the electron transport layer.

6. The preparation method according to claim 5, characterized in that: The electron transport layer was co-evaporated from C60 and metallic silver at a deposition rate of 40:(1~8), with a vacuum degree of 5×10⁻⁶ during co-evaporation. -4 Below Pa.

7. The preparation method according to claim 5, characterized in that: First, a SnO2 layer is deposited on the electron transport layer, and then step S05 is performed. The SnO2 layer is prepared by atomic layer deposition process, using tetra(dimethylamino)tin as the tin source and deionized water as the oxygen source. The deposition temperature is 110~130℃ and the deposition thickness is 15~30nm.

8. The preparation method according to claim 5, characterized in that: The hole transport layer is prepared by spin-coating a MeO-2PACz solution onto the surface of the intermediate composite linker layer at a spin speed of 3000-4000 rpm for 30-45 s, followed by annealing at 110-130℃.

9. The preparation method according to claim 5, characterized in that: The perovskite layer is prepared by a stepwise spin coating method. First, spin coating is performed at 1500-2500 rpm for 10-30 seconds, followed by spin coating at 4500-5500 rpm for 20-40 seconds. Ethyl acetate is added as an anti-solvent 5-15 seconds before the end of the second spin coating step. Finally, the layer is annealed at 100-120°C.

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