Micro-nano solar cell based on van der Waals heterojunction and preparation method thereof

Abstract

The present invention provides a micro-nano solar cell based on a van der Waals heterojunction, which relates to the technical field of solar cell preparation. The main structure, from bottom to top, is: a bottom low-resistance metal conductive electrode, a black phosphorus film, a carbon nanotube film, a molybdenum disulfide film, and a top transparent conductive electrode. The bottom low-resistance metal conductive electrode is made of titanium metal, the black phosphorus film is a p-type 5-10 layer direct bandgap film sample, the carbon nanotube film is freely constructed from semiconducting intrinsic single-arm carbon nanotubes with a bandgap of about 0.6 eV, the molybdenum disulfide film is an n-type single-layer direct bandgap film sample, and the top transparent conductive electrode is a fluorine-doped SnO2 transparent conductive glass FTO material. The present invention is based on a van der Waals heterostructure micro-nano solar cell made of different low-dimensional nanomaterials, which can effectively improve the problems of low photosensitivity and insufficient light absorption capacity existing in existing micro-nano solar cells; the preparation method is based on the combined application of micromachining technology, surface passivation technology, and substrate transfer technology.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and in particular to a micro-nano solar cell based on a van der Waals heterojunction and a preparation method thereof. Background Art

[0002] In recent years, numerous studies have demonstrated that thin films of nanomaterials are ideal materials for solar cells. By efficiently capturing photon energy across a wide spectral range and then rapidly separating and transmitting photogenerated carriers, nanomaterials can achieve very high photoelectric conversion efficiencies. Experiments have demonstrated that two-dimensional materials, such as black phosphorus and molybdenum disulfide, and one-dimensional materials, such as carbon nanotubes, possess excellent photovoltaic performance.

[0003] After obtaining high-quality photovoltaic materials, further improving the light absorption performance of solar cells requires designing a more rational cell structure. Artificially constructing a heterostructure of multiple materials is an effective cell design approach. Recently, van der Waals heterojunctions have garnered widespread research interest. These are artificially controlled "new" materials formed by stacking low-dimensional nanomaterials with different properties in a selected order. Research has found that van der Waals heterojunctions offer numerous advantages in photovoltaic applications: Because the interlayer interactions between these heterojunctions are intermolecular, adjacent layers are no longer constrained by lattice matching; their construction based on two-dimensional layered materials offers exceptionally strong carrier separation capabilities; and their ultra-thin thickness and unique two-dimensional structure contribute to their robust photoelectric response.

[0004] Therefore, the artificial stacked van der Waals heterostructure based on low-dimensional nanomaterials is a main structural design scheme for ultra-thin, flexible, and efficient micro-nano solar cells, which is expected to improve the problems of low photosensitivity and insufficient light absorption capacity in existing micro-nano solar cells. Summary of the Invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a micro-nano solar cell based on van der Waals heterojunction and a preparation method thereof.

[0006] According to the present invention, a micro-nano solar cell based on a van der Waals heterojunction is provided, which includes a bottom low-resistance metal conductive electrode, a black phosphorus film, a carbon nanotube film, a molybdenum disulfide film and a top transparent conductive electrode. The black phosphorus film is provided on the bottom low-resistance metal conductive electrode, the carbon nanotube film is provided on the black phosphorus film, the molybdenum disulfide film is provided on the carbon nanotube film, and the top transparent conductive electrode is provided on the molybdenum disulfide film.

[0007] Preferably, the bottom low-resistance metal conductive electrode is made of titanium.

[0008] Preferably, the black phosphorus film is a p-type 5-10-layer direct bandgap film sample.

[0009] Preferably, the single layer thickness of the black phosphorus film is 0.4-0.6 nm.

[0010] Preferably, the carbon nanotube film is freely constructed from semiconductor intrinsic single-arm carbon nanotubes with a band gap of about 0.6 eV.

[0011] Preferably, the thickness of the carbon nanotube film is 1.84-1.86 μm.

[0012] Preferably, the molybdenum disulfide film is an n-type single-layer direct bandgap film sample.

[0013] Preferably, the thickness of a single layer of the molybdenum disulfide film is 0.8-1.0 nm.

[0014] Preferably, the top transparent conductive electrode is made of fluorine-doped SnO2 transparent conductive glass FTO material.

[0015] The present invention also provides a method for preparing a micro-nano solar cell based on a van der Waals heterojunction, comprising the following steps:

[0016] S1. Prepare the bottom low-resistance metal conductive electrode by evaporation method using micromachining technology;

[0017] S2. Preparation of black phosphorus thin films by chemical vapor deposition using micromachining technology;

[0018] S3, preparation of carbon nanotube thin films by spin coating using micromachining technology;

[0019] S4, preparing MoS2 thin films by chemical vapor deposition method using micromachining technology;

[0020] S5, preparing the top transparent conductive electrode by sputtering method using micromachining technology;

[0021] S6. With the help of surface passivation technology and substrate transfer technology, the bottom low-resistance metal conductive electrode, black phosphorus film, carbon nanotube film, molybdenum disulfide film and top transparent conductive electrode are artificially stacked from bottom to top.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention can form a good titanium / black phosphorus low-resistance contact with the semiconductor nanomaterial by designing the underlying titanium metal conductive electrode;

[0024] 2. By optimizing the micro-machining technology, surface passivation technology, and substrate transfer technology of nano-thin film materials, the present invention constructs a close-contact thin film interface with advantages such as atomic-level flatness and clean surface, effectively improving the separation and transmission efficiency of photogenerated carriers at the interface in the solar cell;

[0025] 3. By regulating the band gaps of the three nano-film materials, the present invention can ensure that the band gaps of the three nano-materials increase in sequence from bottom to top to match the solar spectrum as much as possible, which is conducive to the wide-spectrum absorption of sunlight by the solar cell;

[0026] 4. The present invention enhances the light absorption efficiency of semiconductor nanomaterials by selecting a few-layer black phosphorus and a single-layer molybdenum disulfide thin film material with a direct band gap;

[0027] 5. The present invention uses p-type black phosphorus, i-type (intrinsic) carbon nanotubes and n-type molybdenum disulfide as light-absorbing materials, and artificially constructs a pin van der Waals heterojunction through van der Waals forces to enhance the built-in electric field of the solar cell;

[0028] 6. The present invention enhances the light transmittance of the solar cell and reduces the resistivity of the FTO / molybdenum disulfide contact by designing the top FTO transparent conductive electrode.

[0029] 7. The micro-nano solar cell preparation method designed in the present invention is highly innovative and is expected to be expanded in the field of ultra-thin, flexible, high-efficiency, and micro-energy photovoltaics. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0031] Figure 1 Schematic diagram of a micro-nano solar cell based on van der Waals heterojunction of the present invention;

[0032] Figure 2 This is the current density-voltage curve of the micro-nano solar cell under AM1.5G sunlight.

[0033] Numbers in the figure:

[0034] Bottom layer low-resistance metal conductive electrode 1, black phosphorus film 2, carbon nanotube film 3, molybdenum disulfide film 4, top layer transparent conductive electrode 5. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0036] Example 1

[0037] According to the present invention, a micro-nano solar cell based on van der Waals heterojunction is provided. Figure 1As shown, it includes a bottom low-resistance metal conductive electrode 1, a black phosphorus film 2, a carbon nanotube film 3, a molybdenum disulfide film 4 and a top transparent conductive electrode 5. The black phosphorus film 2 is provided on the bottom low-resistance metal conductive electrode 1, the carbon nanotube film 3 is provided on the black phosphorus film 2, the molybdenum disulfide film 4 is provided on the carbon nanotube film 3, and the top transparent conductive electrode 5 is provided on the molybdenum disulfide film 4.

[0038] A van der Waals heterojunction is a micro-nanostructure artificially constructed through intermolecular van der Waals forces using micromachining, surface passivation, and substrate transfer techniques of nanofilm materials. The bottom low-resistance metal conductive electrode 1 is made of titanium. The black phosphorus film 2 is a p-type 5-10-layer (single-layer thickness 0.4-0.6nm) direct bandgap film sample. The carbon nanotube film 3 (densified carbon nanotube film thickness 1.84-1.86μm) is freely constructed from semiconducting intrinsic single-arm carbon nanotubes with a bandgap of approximately 0.6eV. The molybdenum disulfide film 4 is an n-type single-layer (single-layer thickness 0.8-1.0nm) direct bandgap film sample. The top transparent conductive electrode 5 is made of fluorine-doped SnO2 transparent conductive glass (FTO) material.

[0039] Example 2

[0040] This embodiment 2 is completed on the basis of embodiment 1, specifically:

[0041] The main structure of the micro-nano solar cell based on van der Waals heterojunction is as follows from bottom to top: bottom low-resistance metal conductive electrode 1, black phosphorus film 2, carbon nanotube film 3, molybdenum disulfide film 4 and top transparent conductive electrode 5 (such as Figure 1 ). Among them, the bottom low-resistance metal conductive electrode 1 is made of metal titanium material, the black phosphorus film 2 is made of p-type 5-10 layers (single layer thickness is about 0.5nm) direct band gap film sample, the carbon nanotube film 3 (densified carbon nanotube film thickness is about 1.85μm) is freely built by semiconductor intrinsic single-arm carbon nanotubes with a band gap of about 0.6eV, the molybdenum disulfide film 4 is made of n-type single layer (single layer thickness is about 0.9nm) direct band gap film sample, and the top transparent conductive electrode 5 is made of fluorine-doped SnO2 transparent conductive glass FTO material. Under AM1.5G sunlight irradiation, the circuit current density of the prepared micro-nano solar cell can reach 12.7mA / cm 2 , the open circuit voltage is 0.34V, the fill factor is 0.78, and the solar cell efficiency can reach 3.37% (see Figure 2 ).

[0042] Example 3

[0043] The present invention also provides a method for preparing a micro-nano solar cell based on a van der Waals heterojunction according to embodiment 1 or 2, comprising the following steps:

[0044] S1. Prepare the bottom low-resistance metal conductive electrode by evaporation method using micromachining technology;

[0045] S2. Preparation of black phosphorus thin films by chemical vapor deposition using micromachining technology;

[0046] S3, preparation of carbon nanotube thin films by spin coating using micromachining technology;

[0047] S4, preparing MoS2 thin films by chemical vapor deposition method using micromachining technology;

[0048] S5, preparing the top transparent conductive electrode by sputtering method using micromachining technology;

[0049] S6. With the help of surface passivation technology and substrate transfer technology, the bottom low-resistance metal conductive electrode, black phosphorus film, carbon nanotube film, molybdenum disulfide film and top transparent conductive electrode are artificially stacked from bottom to top.

[0050] Comparative Example 1

[0051] Comparative Example 1 is based on Example 2, except that the number of layers of the black phosphorus film 2 is reduced, the sample composition of the carbon nanotube film 3 is diversified (using carbon nanotubes of different chirality), and the number of layers of the molybdenum disulfide film 4 is increased. Specifically:

[0052] The main structure of the micro-nano solar cell based on the van der Waals heterojunction is as follows from bottom to top: bottom low-resistance metal conductive electrode 1, black phosphorus film 2, carbon nanotube film 3, molybdenum disulfide film 4 and top transparent conductive electrode 5. Among them, the bottom low-resistance metal conductive electrode 1 is made of titanium material, the black phosphorus film 2 is made of p-type 1-4 layers of direct bandgap film sample, the carbon nanotube film 3 is freely constructed by carbon nanotubes mixed with different chirality, the molybdenum disulfide film 4 is made of 3-10 layers of indirect bandgap film sample, and the top transparent conductive electrode 5 is made of fluorine-doped SnO2 transparent conductive glass FTO material. Under the irradiation of AM1.5G sunlight, the circuit current density of the prepared micro-nano solar cell can reach 9.8mA / cm 2 , the open circuit voltage is 0.25V, the fill factor is 0.62, and the solar cell efficiency can reach 1.52%.

[0053] Comparative Example 2

[0054] Comparative Example 2 is based on Example 2, except that the number of layers of the black phosphorus film 2 is increased, the sample composition of the carbon nanotube film 3 (single-arm / multi-arm carbon nanotubes) is diversified, the number of layers of the molybdenum disulfide film 4 is increased, and the material of the top transparent conductive electrode 5 is changed. Specifically:

[0055] The main structure of the micro-nano solar cell based on the van der Waals heterojunction is as follows from bottom to top: bottom low-resistance metal conductive electrode 1, black phosphorus film 2, carbon nanotube film 3, molybdenum disulfide film 4 and top transparent conductive electrode 5. Among them, the bottom low-resistance metal conductive electrode 1 is made of titanium material, the black phosphorus film 2 is made of p-type 8-20 layers of direct bandgap film sample, the carbon nanotube film 3 is made of single-arm / multi-arm mixed carbon nanotubes freely constructed, the molybdenum disulfide film 4 is made of 5-16 layers of indirect bandgap film sample, and the top transparent conductive electrode 5 is made of transparent conductive glass ITO material. Under AM1.5G sunlight irradiation, the circuit current density of the prepared micro-nano solar cell can reach 9.6mA / cm 2 , the open circuit voltage is 0.24V, the fill factor is 0.59, and the solar cell efficiency can reach 1.36%.

[0056] Comparative Example 3

[0057] Comparative Example 3 is based on Example 3, but the stacking order of the black phosphorus film, the carbon nanotube film, and the molybdenum disulfide film from bottom to top is adjusted to molybdenum disulfide film, carbon nanotube film, and black phosphorus film.

[0058] The preparation method of a micro-nano solar cell based on a van der Waals heterojunction includes the following steps: preparing a bottom low-resistance metal conductive electrode by a micro-machining technology evaporation method, preparing a black phosphorus film by a micro-machining technology chemical vapor deposition method, preparing a carbon nanotube film by a micro-machining technology spin coating method, preparing a molybdenum disulfide film by a micro-machining technology chemical vapor deposition method, preparing a top transparent conductive electrode by a micro-machining technology sputtering method, and artificially stacking the bottom low-resistance metal conductive electrode, molybdenum disulfide film, carbon nanotube film, black phosphorus film and top transparent conductive electrode from bottom to top with the help of surface passivation technology and substrate transfer technology. Under the irradiation of AM1.5G sunlight, the circuit current density of the prepared micro-nano solar cell can reach 10.2mA / cm 2 , open circuit voltage is 0.25V, fill factor is 0.63, and solar cell efficiency can reach 1.61%

[0059] In summary, the present invention improves the low photosensitivity and insufficient light absorption capacity of existing micro-nano solar cells by optimizing the structural design of micro-nano solar cells and improving the microfabrication, surface passivation, and substrate transfer technologies of nano-thin films. The results of Examples 2 and 3, combined with Comparative Examples 1-3, demonstrate that the main structural design method for micro-nano solar cells based on van der Waals heterojunctions achieves excellent solar cell efficiency, providing a useful reference for the subsequent preparation of ultrathin, flexible, and efficient micro-nano heterostructure photovoltaic devices.

[0060] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0061] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A micro-nano solar cell based on van der Waals heterojunction, characterized in that: The invention comprises a bottom low-resistance metal conductive electrode (1), a black phosphorus film (2), a carbon nanotube film (3), a molybdenum disulfide film (4), and a top transparent conductive electrode (5); the black phosphorus film (2) is provided on the bottom low-resistance metal conductive electrode (1); the carbon nanotube film (3) is provided on the black phosphorus film (2); the molybdenum disulfide film (4) is provided on the carbon nanotube film (3); and the top transparent conductive electrode (5) is provided on the molybdenum disulfide film (4).

2. The micro-nano solar cell based on van der Waals heterojunction according to claim 1, characterized in that: The bottom low-resistance metal conductive electrode (1) is made of titanium metal.

3. The micro-nano solar cell based on van der Waals heterojunction according to claim 1, characterized in that: The black phosphorus film (2) is a p-type 5-10 layer direct band gap film sample.

4. The micro-nano solar cell based on van der Waals heterojunction according to claim 3, characterized in that: The single layer thickness of the black phosphorus film (2) is 0.4-0.6 nm.

5. The micro-nano solar cell based on van der Waals heterojunction according to claim 1, characterized in that: The carbon nanotube film (3) is freely constructed from semiconductor intrinsic single-arm carbon nanotubes with a band gap of about 0.6 eV.

6. The micro-nano solar cell based on van der Waals heterojunction according to claim 5, characterized in that: The thickness of the carbon nanotube film (3) is 1.84-1.86 μm.

7. The micro-nano solar cell based on van der Waals heterojunction according to claim 1, characterized in that: The molybdenum disulfide film (4) is an n-type single-layer direct bandgap film sample.

8. The micro-nano solar cell based on van der Waals heterojunction according to claim 7, characterized in that: The monolayer thickness of the molybdenum disulfide film (4) is 0.8-1.0 nm.

9. The micro-nano solar cell based on van der Waals heterojunction according to claim 1, characterized in that: The top transparent conductive electrode (5) is made of fluorine-doped SnO2 transparent conductive glass FTO material.

10. A method for preparing a micro-nano solar cell based on a van der Waals heterojunction according to any one of claims 1 to 9, characterized in that: The steps include: S1. preparing the bottom low-resistance metal conductive electrode (1) by a micromachining technology evaporation method; S2, preparing the black phosphorus film (2) by a micromachining technology chemical vapor deposition method; S3, preparing the carbon nanotube film (3) by a micromachining technology spin coating method; S4, preparing the molybdenum disulfide thin film (4) by a micromachining technology chemical vapor deposition method; S5, preparing the top transparent conductive electrode (5) by a micromachining technology sputtering method; S6. Using surface passivation technology and substrate transfer technology, the bottom low-resistance metal conductive electrode (1), the black phosphorus film (2), the carbon nanotube film (3), the molybdenum disulfide film (4) and the top transparent conductive electrode (5) are manually stacked in sequence from bottom to top.

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