A solar cell with a p / n vertical interdigitated heterojunction structure and a preparation method thereof

Abstract

The application discloses a solar cell with a P / N vertical interaction heterojunction structure and a preparation method thereof, and belongs to the technical field of solar cells. The application aims to solve the core problems of process complexity, large optical / electricity loss and poor stability of a traditional laminated solar cell caused by the dependence on an intermediate connecting layer, simultaneously solve the problem of high cost of a traditional doctor blade coating nano-imprint technology, and cooperatively optimize the contradiction between light absorption and charge collection in the P / N heterojunction. The cooperative design of the photo-electric structure synchronously improves the photon absorption efficiency of the cell, realizes more sufficient and more balanced utilization of the solar spectrum, and provides a novel solar cell structure and method with high efficiency, high stability and relatively simple preparation process. Therefore, the technical scheme provides a new path with great potential for developing a next-generation solar cell with high efficiency, low process complexity, low cost and excellent light management function.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a solar cell with a P / N vertically interleaved heterojunction structure and its fabrication method. Background Technology

[0002] Against the backdrop of deepening globalization and industrialization, fossil fuels have long served as the core driving force of global economic development. However, their non-renewable nature has led to energy supply crises, and the severe challenges posed by combustion, such as climate change and environmental pollution, have forced the international community to turn its attention to sustainable clean energy systems. Among various renewable energy sources, solar energy, due to its wide distribution, theoretically unlimited reserves, and zero-carbon emission characteristics during utilization, is considered one of the key directions for future energy structure transformation. Photovoltaic power generation technology, with its high degree of modularity, strong adaptability to various scenarios, and direct energy conversion path, has become the most mature and dominant method for large-scale solar energy utilization, boasting the largest installed capacity.

[0003] Currently, the focus of the photovoltaic industry has shifted from simple scale expansion to pursuing higher photoelectric conversion efficiency and lower levelized cost of electricity (LCOE). However, the efficiency of traditional single-junction solar cells is limited by the Shockley-Quiseur (SQ) theoretical limit, while multi-junction tandem cells, although capable of breaking this limit, face industrialization challenges due to the need for complex intermediate connecting layers (tunnel junctions), strict lattice and current matching, and high manufacturing costs. The introduction of intermediate connecting layers not only increases process complexity and light loss, but their interface defects are also the main cause of nonradiative recombination of charge carriers and open-circuit voltage loss. Therefore, developing a novel cell structure that eliminates the need for intermediate connecting layers and simultaneously achieves broad-spectrum high-efficiency absorption and rapid charge extraction is a critical problem that urgently needs to be solved in the photovoltaic field. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a solar cell with a P / N vertical interactive heterojunction structure and a method for its fabrication, so as to achieve the purpose of simultaneously realizing broadband high-efficiency absorption and rapid charge extraction without the need for an intermediate connecting layer.

[0005] To achieve the above objectives, the technical solution adopted by this invention is to provide a method for fabricating a solar cell with a P / N vertically interlocked heterojunction structure, comprising the following steps: S1: Dissolve nickel oxide in water, add hydrogen peroxide to the resulting solution, and mix thoroughly to obtain a nickel oxide dispersion; S2: Spin-coat the nickel oxide dispersion onto the pretreated substrate and perform a first annealing treatment to form a nickel oxide film on the substrate; then spin-coat the MeO-2PACz / ethanol solution onto the nickel oxide film and perform a second annealing treatment to form a double hole transport layer on the substrate. S3: PbI2, formaldehyde iodide (FAI), CsCl, methylammonium iodide (MAI) and RbI are co-dissolved in a mixed solvent to obtain a precursor solution; the mixed solvent is composed of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. S4: Spin-coat the precursor solution onto the double hole transport layer, then evacuate in a vacuum chamber to form a precursor film on the double hole transport layer; then imprint the precursor film using a sapphire substrate wafer template to form a periodic hole structure on the precursor film, followed by annealing. S5: N-type semiconductors and P-type semiconductors are blended in chlorobenzene to obtain a mixed solution; then the mixed solution is spin-coated onto the annealed precursor film to form an organic layer. S6: Deposit BCP and silver electrode on the organic layer to obtain the final product.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the concentration of the nickel oxide solution obtained in S1 was 10 mg / mL; after adding hydrogen peroxide, the molar percentage of hydrogen peroxide in the solution was 40 mol.%.

[0008] Furthermore, the substrate is made of FTO, and the pretreatment method of the substrate is to place the substrate in an ultraviolet ozone cleaner and irradiate it with ultraviolet light with a wavelength of 185nm for 20 minutes.

[0009] Furthermore, in S2, the spin-coating speed of the nickel oxide dispersion was 2000 rpm, and the spin-coating time was 40 s; the temperature of the first annealing treatment was 120℃, and the first annealing time was 20 min; the spin-coating speed of the MeO-2PACz / ethanol solution was 3000 rpm, and the spin-coating time was 30 s; the concentration of the MeO-2PACz / ethanol solution was 0.5 mg / mL; and the temperature of the second annealing treatment was 120℃, and the second annealing time was 20 min.

[0010] Furthermore, the feed-to-liquid ratio of PbI2, FAI, CsCl, MAI, RbI and the mixed solvent in S3 is 690~695mg: 230~235mg: 12~13mg: 11~12mg: 9~10mg: 1mL.

[0011] Furthermore, before spin-coating the precursor solution, S4 first spin-coats a wetting solution onto the double-layer hole transport layer. The spin-coating speed of the wetting solution is 4000 rpm and the spin-coating time is 20 s. The concentration of the wetting solution is 1 mg / mL, and its solute is phenylethyl ammonium iodide (PEAI) and its solvent is N,N-dimethylformamide.

[0012] Furthermore, in S4, the precursor solution is spin-coated first at 1000 rpm for 8 seconds, and then at 5000 rpm for 10 seconds; the imprinting pressure is 120 bar, and the imprinting time is 60 seconds; the pore spacing of the periodic pore structure is 1000 nm, and the pore depth is 50 nm.

[0013] Furthermore, the annealing temperature in S4 is 110℃, and the annealing time is 60min.

[0014] Furthermore, the N-type semiconductor is PY-IT, the P-type semiconductor is D18, the mass ratio of PY-IT to D18 is 5:1, and the concentration of the mixed solution is 10 mg / mL.

[0015] The present invention also discloses a solar cell with a P / N vertically interleaved heterojunction structure prepared by the above-described preparation method.

[0016] The beneficial effects of this invention are: This invention aims to solve the core problems of traditional tandem solar cells, such as cumbersome manufacturing processes, high optical and electrical losses, and poor interface stability due to their reliance on complex intermediate connecting layers. It also addresses the contradiction between sufficient light absorption and efficient charge collection in existing planar or quasi-planar heterojunction structures. This invention provides a novel solar cell with a three-dimensional P / N vertically interpenetrating heterojunction structure. This structure physically integrates the functions of wide-bandgap and narrow-bandgap light-absorbing materials, omitting all intermediate connecting layers. This simplifies the manufacturing process, reduces costs, and simultaneously enhances light-harvesting capability and carrier collection efficiency through precise control of the interface morphology, significantly improving the device's photoelectric conversion efficiency. Furthermore, this structure forms a porous array structure with specific periodicity and depth within the metal halide light-absorbing layer, and fills this structure with organic semiconductor materials. This achieves three-dimensional interpenetration and cross-linking of P-type and N-type materials within the active region, forming a highly efficient vertically interpenetrating heterojunction. This structure effectively increases the P / N interface contact area, shortens the carrier transport distance to the electrode, and enhances the light-trapping effect of photons within the active layer.

[0017] This invention achieves the following by constructing a three-dimensional P / N vertically interpenetrating heterojunction structure: 1. Simplified structure and performance breakthrough: The complex intermediate connecting layer is completely eliminated. The P-type layer and N-type layer are directly contacted through a single stamping process, which simplifies the process and effectively solves technical problems such as many interface defects and complex preparation conditions. At the same time, it achieves a PCE of more than 26%.

[0018] 2. Photovoltaic synergy: The three-dimensional P / N vertical interactive heterojunction structure enables precise control of the interface structure, which greatly improves light absorption (especially in the near-infrared region) and shortens the charge extraction path, thus fundamentally alleviating the trade-off between light absorption and charge collection.

[0019] 3. Low cost and reusability: Using sapphire substrate wafers as templates enables low-cost technology. The robust sapphire substrate wafers can be reused repeatedly, improving utilization. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a solar cell with a P / N vertically intersecting heterojunction structure prepared according to the present invention; Figure 2 The current density-voltage (JV) curves of the solar cells obtained in Examples 1-5 are shown. Figure 3 This is a comparison diagram of the simulated carrier generation rate spatial distribution of the solar cell device in Comparative Example 1 and the solar cell device in Example 1 under illumination of a specific wavelength. Figure 4 The graph shows a comparison of the absorption, transmission, and reflection spectra of the solar cell device in Comparative Example 1 and the solar cell device in Example 1. Figure 5 The image shows an atomic force microscope (AFM) image and height distribution diagram of the thin film with the P / N vertically interpenetrating heterojunction structure in the solar cell with the P / N vertically interpenetrating heterojunction structure prepared in Example 1. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0022] A solar cell with a P / N vertically interleaved heterojunction structure, the structure of which is as follows: Figure 1 As shown; the solar cell in this embodiment is manufactured through the following steps: S1: Nickel oxide (NiO) x The nickel oxide was dissolved in water to obtain a solution with a concentration of 10 mg / mL. Hydrogen peroxide was added to the solution (after adding hydrogen peroxide, the molar percentage of hydrogen peroxide in the solution was 40 mol.%). The solution was then sonicated at low temperature for 30 min and filtered through a 0.22 μm polytetrafluoroethylene filter membrane to obtain a nickel oxide dispersion. S2: The FTO substrate was placed in an ultraviolet ozone cleaner and irradiated with ultraviolet light at a wavelength of 185nm for 20 minutes. Then, a nickel oxide dispersion was spin-coated onto the pretreated substrate and subjected to a first annealing treatment to form a nickel oxide film on the substrate. The spin-coating speed of the nickel oxide dispersion was 2000 rpm, the spin-coating time was 40 s, the temperature of the first annealing treatment was 120℃, and the first annealing time was 20 minutes. Next, a MeO-2PACz / ethanol solution was spin-coated onto the nickel oxide film and subjected to a second annealing treatment to form a double hole transport layer on the substrate. The spin-coating speed of the MeO-2PACz / ethanol solution was 3000 rpm, the spin-coating time was 30 s, the concentration of the MeO-2PACz / ethanol solution was 0.5 mg / mL, and the temperature of the second annealing treatment was 120℃, and the second annealing time was 20 minutes. S3: PbI2, FAI, CsCl, MAI, and RbI were co-dissolved in a mixed solvent and stirred for 8 hours. The mixture was then filtered through a 0.22 μm polytetrafluoroethylene membrane to obtain a precursor solution. The mixed solvent was composed of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. The feed-to-liquid ratio of PbI2, FAI, CsCl, MAI, RbI, and the mixed solvent was 691.5 mg: 232.2 mg: 12.6 mg: 11.9 mg: 9.5 mg: 1 mL. S4: A wetting solution was spin-coated onto the double-layer hole transport layer to improve wettability. The spin-coating speed was 4000 rpm and the spin-coating time was 20 s. The concentration of the wetting solution was 1 mg / mL, the solute was PEAI, and the solvent was N,N-dimethylformamide. Then, a precursor solution was spin-coated onto the double-layer hole transport layer. The precursor solution was first spin-coated at 1000 rpm for 8 s, and then at 5000 rpm for 10 s. Subsequently, a vacuum chamber was evacuated for 5 s to form a precursor film on the double-layer hole transport layer. The precursor film was then imprinted using a sapphire substrate wafer template to form a periodic hole structure on the precursor film. The imprinting pressure was 120 bar and the imprinting time was 60 s. The hole spacing of the formed periodic hole structure was 1000 nm and the hole depth was 50 nm. Finally, an annealing treatment was performed at a temperature of 110 °C for 60 min. S5: N-type semiconductor PY-IT and P-type semiconductor D18 are mixed in chlorobenzene at a mass ratio of 5:1 to obtain a mixed solution with a concentration of 10 mg / mL; then the mixed solution is spin-coated onto the annealed precursor film at a speed of 5000 rpm (spin-coating time is 20 s) to form an organic layer. S6: A solar cell with a P / N vertically interleaved heterojunction structure is obtained by depositing a 6nm BCP and a 120nm silver electrode on the organic layer through thermal evaporation.

[0023] Example 2 A solar cell with a P / N vertically interleaved heterojunction structure is prepared by adjusting the imprinting pressure in S4 to 80 bar, while the other conditions are the same as in Example 1, compared with Example 1.

[0024] Example 3 A solar cell with a P / N vertically interleaved heterojunction structure is prepared by adjusting the imprinting pressure in S4 to 160 bar, while the other conditions are the same as in Example 1, compared with Example 1.

[0025] Example 4 A solar cell with a P / N vertically interleaved heterojunction structure is prepared by adjusting the imprinting pressure in S4 to 240 bar, while the other conditions are the same as in Example 1, compared with Example 1.

[0026] Example 5 A solar cell with a P / N vertically interleaved heterojunction structure is prepared by adjusting the imprinting pressure in S4 to 320 bar, while the other conditions are the same as in Example 1, compared with Example 1.

[0027] Comparative Example 1 A solar cell with a P / N heterojunction structure is prepared by the following steps in this comparative example: S1: Nickel oxide (NiO) x The nickel oxide was dissolved in water to obtain a solution with a concentration of 10 mg / mL. Hydrogen peroxide was added to the solution (after adding hydrogen peroxide, the molar percentage of hydrogen peroxide in the solution was 40 mol.%). The solution was then sonicated at low temperature for 30 min and filtered through a 0.22 μm polytetrafluoroethylene filter membrane to obtain a nickel oxide dispersion. S2: The FTO substrate was placed in an ultraviolet ozone cleaner and irradiated with ultraviolet light at a wavelength of 185nm for 20 minutes. Then, a nickel oxide dispersion was spin-coated onto the pretreated substrate and subjected to a first annealing treatment to form a nickel oxide film on the substrate. The spin-coating speed of the nickel oxide dispersion was 2000 rpm, the spin-coating time was 40 s, the temperature of the first annealing treatment was 120℃, and the first annealing time was 20 minutes. Next, a MeO-2PACz / ethanol solution was spin-coated onto the nickel oxide film and subjected to a second annealing treatment to form a double hole transport layer on the substrate. The spin-coating speed of the MeO-2PACz / ethanol solution was 3000 rpm, the spin-coating time was 30 s, the concentration of the MeO-2PACz / ethanol solution was 0.5 mg / mL, and the temperature of the second annealing treatment was 120℃, and the second annealing time was 20 minutes. S3: PbI2, FAI, CsCl, MAI, and RbI were co-dissolved in a mixed solvent and stirred for 8 hours. The mixture was then filtered through a 0.22 μm polytetrafluoroethylene membrane to obtain a precursor solution. The mixed solvent was composed of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. The feed-to-liquid ratio of PbI2, FAI, CsCl, MAI, RbI, and the mixed solvent was 691.5 mg: 232.2 mg: 12.6 mg: 11.9 mg: 9.5 mg: 1 mL. S4: A wetting solution was spin-coated onto the double-layer hole transport layer to improve wettability. The spin-coating speed was 4000 rpm and the spin-coating time was 20 s. The concentration of the wetting solution was 1 mg / mL, the solute was PEAI, and the solvent was N,N-dimethylformamide. Then, the precursor solution was spin-coated onto the double-layer hole transport layer. The precursor solution was first spin-coated at 1000 rpm for 8 s, and then at 5000 rpm for 10 s. Subsequently, a vacuum chamber was evacuated for 5 s to form a precursor film on the double-layer hole transport layer. Finally, an annealing treatment was performed at 110℃ for 60 min. S5: N-type semiconductor PY-IT and P-type semiconductor D18 are mixed in chlorobenzene at a mass ratio of 5:1 to obtain a mixed solution with a concentration of 10 mg / mL; then the mixed solution is spin-coated onto the annealed precursor film at a speed of 5000 rpm (spin-coating time is 20 s) to form an organic layer. S6: A solar cell with a P / N vertically interleaved heterojunction structure is obtained by depositing a 6nm BCP and a 120nm silver electrode on the organic layer through thermal evaporation.

[0028] Experimental Example The current density-voltage (JV) curves of the solar cells obtained in Examples 1-5 are shown below. Figure 2 As shown. From Figure 2 As can be seen from this, the open-circuit voltage (V) OC ), short-circuit current density (J SC Both the open-circuit voltage (OPV) and fill factor (FF) exhibit a pressure-dependent trend: compared to planar devices, they initially increase with increasing pressure, but subsequently decrease at even higher pressures. Devices optimized for 120 bar pressure demonstrate superior performance, with an open-circuit voltage of 1.175 V and a short-circuit current density of 26.47 mAcm⁻¹. -2 The fill factor reached 84.40%, ultimately achieving a photoelectric conversion efficiency (PCE) of 26.24%.

[0029] The spatial distribution of simulated carrier generation rate under specific wavelength illumination is shown in the figure below for the solar cell device (Planar) in Comparative Example 1 and the solar cell device (Imprinted) in Example 1. Figure 3 As shown. From Figure 3 As can be seen, the three-dimensional P / N vertically interactive heterojunction structure significantly changes the optical field distribution and enhances carrier generation at the interface, while the planar structure exhibits relatively uniform carrier generation. The three-dimensional P / N vertically interactive heterojunction structure device can effectively regulate the electric field distribution and enhance the absorption intensity, thereby improving the overall light utilization and device performance.

[0030] The absorption, transmission, and reflection spectra of the solar cell device (Planar) in Comparative Example 1 and the solar cell device (Imprinted) in Example 1 are compared as follows: Figure 4 As shown. From Figure 4 As can be seen, the absorption of the three-dimensional P / N vertically interactive heterojunction structure film is enhanced in the 550~850nm band, while the transmittance is significantly reduced in the three-dimensional P / N vertically interactive heterojunction structure film. The reflectance of the three-dimensional P / N vertically interactive heterojunction structure film is significantly reduced in the 450~900nm band, indicating that the P / N vertically interactive structure achieves optimization of light capture across the entire wavelength range by extending the optical path and increasing the residence time of photons in the film.

[0031] Atomic force microscopy (AFM) images and height distribution diagrams of the thin film with the P / N vertically interpenetrating heterojunction structure in the solar cell with the P / N vertically interpenetrating heterojunction structure prepared in Example 1 of this invention are shown below. Figure 5 As shown. From Figure 5 As can be seen, the surface of the three-dimensional P / N vertical interactive heterojunction structure exhibits a periodic pore structure with a pore spacing of about 1000 nm and a pore depth of 50 nm, and the surface uniform pore array has been successfully fabricated.

[0032] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A method for fabricating a solar cell with a P / N vertically interleaved heterojunction structure, characterized in that, Includes the following steps: S1: Dissolve nickel oxide in water, add hydrogen peroxide to the resulting solution, and mix well to obtain a nickel oxide dispersion; S2: Spin-coat the nickel oxide dispersion onto the pretreated substrate and perform a first annealing treatment to form a nickel oxide film on the substrate; then spin-coat the MeO-2PACz / ethanol solution onto the nickel oxide film and perform a second annealing treatment to form a double hole transport layer on the substrate. S3: PbI2, FAI, CsCl, MAI and RbI are co-dissolved in a mixed solvent to obtain a precursor solution; the mixed solvent is composed of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:

1. S4: Spin-coat the precursor solution onto the double hole transport layer, then evacuate in a vacuum chamber to form a precursor film on the double hole transport layer; then imprint the precursor film using a sapphire substrate wafer template to form a periodic hole structure on the precursor film, followed by annealing. S5: N-type semiconductors and P-type semiconductors are blended in chlorobenzene to obtain a mixed solution; then the mixed solution is spin-coated onto the annealed precursor film to form an organic layer. S6: Deposit BCP and silver electrode on the organic layer to obtain the final product.

2. The preparation method according to claim 1, characterized in that: The concentration of the nickel oxide solution obtained by S1 is 10 mg / mL; after adding hydrogen peroxide, the molar percentage of hydrogen peroxide in the solution is 40 mol.

3. The preparation method according to claim 1, characterized in that: The substrate is made of FTO, and the pretreatment method of the substrate is to put the substrate into an ultraviolet ozone cleaner and irradiate it with ultraviolet light with a wavelength of 185nm for 20 minutes.

4. The preparation method according to claim 1, characterized in that: The spin-coating speed of the nickel oxide dispersion in S2 was 2000 rpm, and the spin-coating time was 40 s; the temperature of the first annealing treatment was 120℃, and the first annealing time was 20 min; the spin-coating speed of the MeO-2PACz / ethanol solution was 3000 rpm, and the spin-coating time was 30 s; the concentration of the MeO-2PACz / ethanol solution was 0.5 mg / mL; the temperature of the second annealing treatment was 120℃, and the second annealing time was 20 min.

5. The preparation method according to claim 1, characterized in that: The feed-to-liquid ratio of PbI2, FAI, CsCl, MAI, RbI and mixed solvent in S3 is 690~695mg: 230~235mg: 12~13mg: 11~12mg: 9~10mg: 1mL.

6. The preparation method according to claim 1, characterized in that: Before spin-coating the precursor solution, S4 first spin-coats a wetting solution onto the double-layer hole transport layer. The spin-coating speed of the wetting solution is 4000 rpm and the spin-coating time is 20 s. The concentration of the wetting solution is 1 mg / mL, and its solute is PEAI and its solvent is N,N-dimethylformamide.

7. The preparation method according to claim 1, characterized in that: The precursor solution in S4 is spin-coated at 1000 rpm for 8 seconds, and then at 5000 rpm for 10 seconds; the imprinting pressure is 120 bar and the imprinting time is 60 seconds; the pore spacing of the periodic pore structure is 1000 nm and the pore depth is 50 nm.

8. The preparation method according to claim 1, characterized in that: The annealing temperature in S4 is 110℃, and the annealing time is 60min.

9. The preparation method according to claim 1, characterized in that: The N-type semiconductor is PY-IT, the P-type semiconductor is D18, and the mass ratio of PY-IT to D18 is 5:1; the concentration of the mixed solution is 10 mg / mL.

10. A solar cell with a P / N vertically interleaved heterojunction structure prepared by the preparation method according to any one of claims 1 to 9.

Images