Resonant tunneling composite film and solar cell

Abstract

The invention provides a resonant tunneling composite film and a solar cell, and relates to the technical field of solar cells, the resonant tunneling composite film comprises a substrate, and a passivation layer, a first emitter, a second emitter and a third emitter which are at least sequentially arranged on the substrate, the band gap width of the passivation layer is larger than that of the substrate, and the first emitter is arranged on the substrate. The band gap width of the first emitter is smaller than the band gap width of the passivation layer, the band gap width of the second emitter is larger than the band gap width of the first emitter, and the band gap width of the third emitter is smaller than the band gap width of the second emitter. The passivation layer can maintain a good interface passivation effect, potential barriers can be formed at the passivation layer and the second emitter respectively, a potential well can be formed at the first emitter, the thin film structure integrally forms a double-potential-barrier quantum well structure, and the longitudinal carrier transport capacity of the thin film structure is remarkably improved through resonance tunneling.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a resonant tunneling composite film and a solar cell. Background Art

[0002] Among solar cells, heterojunction cells are a very promising high-efficiency crystalline silicon cell technology, and their outstanding advantage is the high open circuit voltage brought by the extremely excellent surface passivation technology. Silicon / perovskite stacked cells prepared on the basis of heterojunction have broader application prospects due to their higher conversion efficiency.

[0003] In the existing silicon heterojunction technology, most of them use hydrogenated amorphous silicon (a-Si:H)-based thin films to passivate the surface of crystalline silicon. This can increase the open circuit voltage of silicon heterojunction (SHJ) solar cells to more than 740mV. This process is the core process of heterojunction cells. Amorphous silicon films are relatively thin (often less than 10nm), so the existing technology technically ignores the impact of the electrical properties and optical absorption properties of amorphous silicon films on the efficiency of SHJ solar cells. Amorphous silicon materials are long-range disordered direct bandgap materials with poor carrier transport capabilities. At the same time, due to the high defect state density, their more obvious optical absorption often cannot be converted into electrical output (photogenerated carrier recombination), which limits the further improvement of SHJ solar cell efficiency. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a resonant tunneling composite film and a solar cell, which can improve the electrical transport performance of the composite film structure while maintaining a good surface passivation function. At the same time, the introduction of wide bandgap materials will improve the short-wave spectral response of the SHJ solar cell and increase its short-circuit current density.

[0005] According to one aspect of an embodiment of the present application, a resonant tunneling composite film is provided, comprising a substrate, and at least a passivation layer, a first emitter, a second emitter and a third emitter sequentially arranged on the substrate, wherein the band gap width of the passivation layer is greater than the band gap width of the substrate, the band gap width of the first emitter is smaller than the band gap width of the passivation layer, the band gap width of the second emitter is greater than the band gap width of the first emitter, and the band gap width of the third emitter is smaller than the band gap width of the second emitter.

[0006] Optionally, a bandgap width of the passivation layer is substantially equal to a bandgap width of the second emitter.

[0007] Optionally, the bandgap width of the first emitter is substantially equal to the bandgap width of the third emitter.

[0008] Optionally, the first emitter, the second emitter and the third emitter are all P-type emitters or are all N-type emitters.

[0009] Optionally, the Fermi energy level of the N-type emitter is higher than the Fermi energy level of the passivation layer; and the Fermi energy level of the P-type emitter is lower than the Fermi energy level of the passivation layer.

[0010] Optionally, when the passivation layer is used as an N-surface, the conduction band bottom of the passivation layer is located above the conduction band bottom of the substrate, and the difference between the conduction band bottom of the passivation layer and the conduction band bottom of the substrate is not less than 0.4 eV; when the passivation layer is used as a P-surface, the valence band top of the passivation layer is located below the valence band top of the substrate, and the difference between the valence band top of the passivation layer and the valence band top of the substrate is not less than 0.4 eV, and the thickness of the passivation layer is less than 10 nm.

[0011] Optionally, when the first emitter is used as the N-surface, the conduction band bottom of the first emitter is below the conduction band bottom of the passivation layer, and the difference between the conduction band bottom of the first emitter and the conduction band bottom of the substrate is not higher than 0.2eV; when the first emitter is used as the P-surface, the valence band top of the first emitter is above the valence band top of the passivation layer, and the difference between the valence band top of the first emitter and the valence band top of the substrate is not higher than 0.2eV; the thickness of the first emitter is between 2nm and 10nm.

[0012] Optionally, when the second emitter is used as the N-surface, the conduction band bottom of the second emitter is above the conduction band bottom of the first emitter, and the difference between the conduction band bottom of the second emitter and the conduction band bottom of the substrate is not less than 0.4 eV; when the second emitter is used as the P-surface, the valence band top of the second emitter is below the valence band top of the first emitter, and the difference between the valence band top of the second emitter and the valence band top of the substrate is not less than 0.4 eV; the thickness of the second emitter is less than 10 nm.

[0013] Optionally, when the third emitter is used as an N-surface, the conduction band bottom of the third emitter is below the conduction band bottom of the second emitter, and the difference between the conduction band bottom of the third emitter and the conduction band bottom of the substrate is not higher than 0.4 eV; when the third emitter is used as a P-surface, the valence band top of the third emitter is above the valence band top of the second emitter, and the difference between the valence band top of the third emitter and the valence band top of the substrate is not higher than 0.4 eV; when the third emitter is used as a P-surface, the thickness of the third emitter is not less than 5 nm.

[0014] Another aspect of the embodiments of the present application provides a solar cell, including: the above-mentioned resonant tunneling composite film.

[0015] The resonant tunneling composite film and solar cell provided in the embodiments of the present application can form at least a passivation layer, a first emitter, a second emitter and a third emitter stacked in sequence on the substrate, wherein the band gap width of the passivation layer is greater than the band gap width of the substrate, the band gap width of the first emitter is smaller than the band gap width of the passivation layer, the band gap width of the second emitter is greater than the band gap width of the first emitter, and the band gap width of the third emitter is smaller than the band gap width of the second emitter, so that the passivation layer can maintain a good interface passivation effect, and can also form potential barriers at the passivation layer and the second emitter, and form a potential well at the first emitter, so that the overall thin film structure forms a double barrier quantum well structure, and the longitudinal carrier transport capacity of the thin film structure is significantly improved by resonant tunneling. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is one of the schematic diagrams of the energy band structure of the resonant tunneling composite film provided in this embodiment; Figure 2 This is the second schematic diagram of the energy band structure of the resonant tunneling composite film provided in this embodiment; Figure 3 This is the third schematic diagram of the energy band structure of the resonant tunneling composite film provided in this embodiment.

[0020] Icon: 100 - substrate; 101 - passivation layer; 102 - first emitter; 103 - second emitter; 104 - third emitter; h - energy band height; d - energy band width. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0022] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does 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. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0023] It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] Please refer to Figure 1 As shown, an embodiment of the present application provides a resonant tunneling composite film (hereinafter referred to as a thin film structure), including: a substrate 100, and at least a passivation layer 101, a first emitter 102, a second emitter 103 and a third emitter 104 arranged in sequence on the substrate 100, the band gap width of the passivation layer 101 is greater than the band gap width of the substrate 100, the band gap width of the first emitter 102 is smaller than the band gap width of the passivation layer 101, the band gap width of the second emitter 103 is greater than the band gap width of the first emitter 102, and the band gap width of the third emitter 104 is smaller than the band gap width of the second emitter 103.

[0025] The substrate 100 may be a single crystal silicon substrate 100 , and at least four thin film layers are disposed on the substrate 100 , which are a passivation layer 101 , a first emitter 102 , a second emitter 103 and a third emitter 104 .

[0026] Wherein, a wide bandgap passivation layer 101 is prepared on the cleaned and textured single crystal silicon textured substrate 100, the bandgap width of the passivation layer 101 is greater than the bandgap width of the substrate 100, the bandgap width is the difference between the conduction band and the valence band, the valence band line is at the bottom and the conduction band line is at the top in the energy band diagram, when the passivation layer 101 is used as an N-face (the passivation layer 101 is an n-type semiconductor), the conduction band bottom of the passivation layer 101 is located above the conduction band bottom of the substrate 100, and the difference between the conduction band bottom of the passivation layer 101 and the conduction band bottom of the substrate 100 is not less than 0.4 eV; when the passivation layer 101 is used as a P-face (the passivation layer 101 is a p-type semiconductor), the valence band top of the passivation layer 101 is located below the valence band top of the substrate 100, and the difference between the valence band top of the passivation layer 101 and the valence band top of the substrate 100 is not less than 0.4 eV; Figure 1 The band structure diagram of the thin film structure of the present application is shown, and the band gap width of the passivation layer 101 is Figure 1 The energy band height h of the corresponding position of the middle passivation layer 101, and similarly the band gap widths of the other layers are Figure 1 The energy band height h at the corresponding position.

[0027] It should be noted that when the passivation layer 101 is used as the N-side, it means that the passivation layer 101 is an n-type semiconductor; when the passivation layer 101 is used as the P-side, it means that the passivation layer 101 is a p-type semiconductor; the first emitter 102, the second emitter 103, and the third emitter 104 described below are similarly referred to and will not be repeated here.

[0028] The passivation layer 101 should have good surface passivation ability; preferably, the passivation layer 101 has a certain amount of free small molecular weight active groups, or can generate free small molecular weight active groups under certain conditions of light, electric field, temperature, etc. The thickness of the passivation layer should be less than 10nm.

[0029] A first emitter 102 with a narrow bandgap is prepared on the passivation layer 101. When the first emitter 102 is used as an N-surface, the bottom position of the conduction band of the first emitter 102 is lower than the bottom position of the conduction band of the passivation layer 101, and the difference between the bottom position of the conduction band of the first emitter 102 and the bottom position of the conduction band of the substrate 100 is not higher than 0.2 eV; when the first emitter 102 is used as a P-surface, the top position of the valence band of the first emitter 102 is higher than the top position of the valence band of the passivation layer 101, and the difference between the top position of the valence band of the first emitter 102 and the top position of the valence band of the substrate 100 is not higher than 0.2 eV; the bandgap width of the first emitter 102 is smaller than the bandgap width of the passivation layer 101, that is, Figure 1 The energy band height h of the first emitter 102 is smaller than the energy band height h of the passivation layer 101 .

[0030] The thickness of the first emitter 102 is between 2 nm and 10 nm. In other words, the thickness of the first emitter 102 is not less than 2 nm and not more than 10 nm.

[0031] A second emitter 103 with a wide bandgap is prepared on the first emitter 102 , and the bandgap width of the second emitter 103 is greater than the bandgap width of the first emitter 102 .

[0032] The positions of the conduction band bottom (when used for N-face) and the valence band top (when used for P-face) of the second emitter 103 should not change much from those of the passivation layer 101. When the second emitter 103 is used as the N-face, the conduction band bottom of the second emitter 103 is located above the conduction band bottom of the first emitter 102, and the difference between the conduction band bottom of the second emitter 103 and the conduction band bottom of the substrate 100 is not less than 0.4 eV; when the second emitter 103 is used as the P-face, the valence band top of the second emitter 103 is located below the valence band top of the first emitter 102, and the difference between the valence band top of the second emitter 103 and the valence band top of the substrate 100 is not less than 0.4 eV, the thickness of the second emitter 103 is less than 10 nm, and the thickness of the second emitter 103 should not be much different from that of the passivation layer 101.

[0033] A third emitter 104 with a narrow band gap is prepared on the second emitter 103 , and the band gap width of the third emitter 104 is smaller than the band gap width of the second emitter 103 .

[0034] The positions of the conduction band bottom (for N-side) and the valence band top (for P-side) of the third emitter 104 should not be much different from those of the first emitter 102 .

[0035] When the third emitter 104 is used as the N-surface, the conduction band bottom of the third emitter 104 is below the conduction band bottom of the second emitter 103, and the difference between the conduction band bottom of the third emitter 104 and the conduction band bottom of the substrate 100 is not higher than 0.4 eV; when the third emitter 104 is used as the P-surface, the valence band top of the third emitter 104 is above the valence band top of the second emitter 103, and the difference between the valence band top of the third emitter 104 and the valence band top of the substrate 100 is not higher than 0.4 eV; when the third emitter 104 is used as the P-surface, the thickness of the third emitter 104 should be no less than 5 nm.

[0036] By setting the relationship between the band gap widths of the above layers, the thin film structure of the present application can be formed. Figure 1 energy band, forming a double barrier at the passivation layer 101 and the second emitter 103, and a potential well at the first emitter 102. The overall thin film structure forms a double barrier quantum well structure, which can significantly improve the longitudinal carrier transport capacity of the thin film structure by using resonant tunneling.

[0037] Of course, on this basis, Figure 1 According to the energy band law, when multiple thin film layers are continuously stacked on the third emitter 104, three potential barriers, four potential barriers, etc. can also be formed, and those skilled in the art can select them according to their needs.

[0038] Thus, in the resonant tunneling composite film provided by the embodiment of the present application, at least a passivation layer 101, a first emitter 102, a second emitter 103 and a third emitter 104 stacked in sequence can be formed on the substrate 100, wherein the band gap width of the passivation layer 101 is greater than the band gap width of the substrate 100, the band gap width of the first emitter 102 is smaller than the band gap width of the passivation layer 101, the band gap width of the second emitter 103 is greater than the band gap width of the first emitter 102, and the band gap width of the third emitter 104 is smaller than the band gap width of the second emitter 103, so that the passivation layer 101 can maintain a good interface passivation effect, and potential barriers can be formed at the passivation layer 101 and the second emitter 103, and a potential well can be formed at the first emitter 102, so that the overall thin film structure forms a double barrier quantum well structure, and the longitudinal carrier transport capacity of the thin film structure is significantly improved by resonant tunneling.

[0039] On this basis, in one embodiment of the present application, the band gap width of the passivation layer 101 is substantially equal to the band gap width of the second emitter 103, that is, the position of the conduction band bottom and the valence band top of the second emitter 103 is not much different from the position of the conduction band bottom and the valence band top of the passivation layer 101, so as to form Figure 1 The energy band height h of the middle passivation layer 101 and the energy band height h of the second emitter 103 are substantially equal.

[0040] The bandgap width of the first emitter 102 is substantially equal to the bandgap width of the third emitter 104, that is, the positions of the bottom of the conduction band and the top of the valence band of the third emitter 104 are not much different from those of the bottom of the conduction band and the top of the valence band of the first emitter 102, forming Figure 1 The energy band height h of the first emitter 102 and the energy band height h of the fourth emitter are substantially equal, thereby finally forming Figure 1 The band structure shown.

[0041] The third emitter 104 should have good electrical properties to form a good ohmic contact with the upper TCO film. The electrical properties include but are not limited to photoconductivity, work function, Fermi level, etc.

[0042] In addition, the first emitter 102, the second emitter 103 and the third emitter 104 can all be P-type emitters, and the Fermi energy level of the P-type emitter should be lower than the Fermi energy level of the passivation layer 101; or, the first emitter 102, the second emitter 103 and the third emitter 104 can all be N-type emitters, and the Fermi energy level of the N-type emitter should be higher than the Fermi energy level of the passivation layer 101.

[0043] In addition, depending on the material of each layer of film, Figure 1 The energy band law can also be changed in many ways. For example, Figure 2 or Figure 3 The energy band, its overall regular trend and Figure 1 The difference is that the energy band structure shape of each layer of the thin film can be changed by adjusting the material or material ratio of each layer of the thin film.

[0044] The choice of material determines the value of the conduction band and the valence band, that is, the value of the band gap width. The band gap width is reflected in Figure 1 , Figure 2 , Figure 3 The energy band height h is the energy band width d, which is determined by the thickness of the thin film layer. The passivation layer 101 and the second emitter 103 form a potential barrier, so Figure 1 to Figure 3 The middle passivation layer 101 and the second emitter 103 can also be called the barrier height and barrier width. The first emitter 102 forms a potential well. Therefore Figure 1 to Figure 3 The width of the first emitter 102 may also be referred to as a potential well width.

[0045] therefore, Figure 2 , Figure 3 In the embodiment, the band gap width of the passivation layer 101 is greater than the band gap width of the substrate 100, the band gap width of the first emitter 102 is less than the band gap width of the passivation layer 101, the band gap width of the second emitter 103 is greater than the band gap width of the first emitter 102, and the band gap width of the third emitter 104 is less than the band gap width of the second emitter 103, so that the overall energy band structure trend remains unchanged and a double barrier quantum well structure can still be formed. However, by adjusting the materials or material ratio of the passivation layer 101 and the second emitter 103, the energy band structure of the passivation layer 101 and the second emitter 103 can be changed from Figure 1 The rectangle becomes Figure 2 The convex structure Figure 3 of the trapezoid; further, Figure 3 The slope of the hypotenuse of the middle trapezoid can also be achieved by adjusting the material of this layer.

[0046] In one embodiment of the present application, the material of the passivation layer 101 is, but is not limited to, silicon oxide, amorphous silicon, microcrystalline silicon, silicon nitride, aluminum oxide, amorphous silicon oxygen, amorphous silicon carbon, microcrystalline silicon oxygen, microcrystalline silicon carbon, titanium dioxide, molybdenum oxide, hafnium oxide, etc.;

[0047] The material of the first emitter 102 includes but is not limited to amorphous germanium, amorphous silicon germanium, microcrystalline silicon germanium, silicon oxide, amorphous silicon, microcrystalline silicon, silicon nitride, aluminum oxide, amorphous silicon oxygen, amorphous silicon carbon, etc.;

[0048] The material of the second emitter 103 is, but not limited to, silicon oxide, amorphous silicon, microcrystalline silicon, silicon nitride, aluminum oxide, amorphous silicon oxygen, amorphous silicon carbon, microcrystalline silicon oxygen, microcrystalline silicon carbon, titanium dioxide, molybdenum oxide, hafnium oxide, etc.;

[0049] The material of the third emitter 104 includes, but is not limited to, amorphous germanium, amorphous silicon germanium, microcrystalline silicon germanium, silicon oxide, amorphous silicon, microcrystalline silicon, silicon nitride, aluminum oxide, amorphous silicon oxygen, amorphous silicon carbon, and the like.

[0050] When the passivation layer 101, the first emitter 102, the second emitter 103 and the third emitter 104 are prepared by the above materials, each layer can be formed into a single-layer film by one material, or each layer can be formed into a composite film by multiple materials. When each layer is a composite film, the positions of its conduction band, valence band and Fermi level should not change significantly, generally within 0.2eV. The multi-layer composite film and the single crystal silicon substrate 100 form a double-barrier single quantum well structure. When the width and height of the barrier and the potential well are matched, the structure can undergo high-probability resonant tunneling, significantly improving the carrier transport capacity of the battery.

[0051] The present application provides application examples of the thin film structure of the present application through the following three embodiments:

[0052] In a first embodiment, an i / n composite resonant tunneling multilayer silicon film for a silicon heterojunction cell is provided, comprising the following steps:

[0053] An amorphous silicon passivation layer 101 is prepared on the cleaned and textured single crystal silicon textured substrate 100 by using PECVD. The band gap width of the amorphous silicon passivation layer 101 is 1.9 eV and the thickness is 4 nm.

[0054] An n-type microcrystalline silicon first emitter 102 is prepared on the amorphous silicon passivation layer 101 by PECVD, and the band gap width of the microcrystalline silicon first emitter 102 is 1.4 eV and the thickness is 3 nm;

[0055] An n-type microcrystalline silicon oxygen second emitter 103 is prepared on the n-type microcrystalline silicon first emitter 102 by PECVD, and the band gap width of the microcrystalline silicon oxygen second emitter 103 is 1.7 eV and the thickness is 4 nm;

[0056] An n-type microcrystalline silicon third emitter 104 is prepared on the n-type microcrystalline silicon oxygen second emitter 103 by using PECVD. The band gap width of the microcrystalline silicon oxygen third emitter 104 is 1.3 eV and the thickness is 4 nm.

[0057] In a second embodiment, an i / p composite resonant tunneling multilayer silicon film for a silicon heterojunction cell is provided, comprising the following steps:

[0058] A silicon oxide passivation layer 101 is prepared on the cleaned and textured single crystal silicon textured substrate 100 by thermal oxidation. The silicon oxide passivation layer 101 has a bandgap of 2.1 eV and a thickness of 2 nm.

[0059] A p-type microcrystalline silicon first emitter 102 is prepared on the passivation layer 101 by PECVD, and the band gap width of the microcrystalline silicon first emitter 102 is 1.4 eV and the thickness is 3 nm;

[0060] A p-type microcrystalline silicon carbon second emitter 103 is prepared on the p-type microcrystalline silicon first emitter 102 by PECVD, and the band gap width of the microcrystalline silicon oxygen second emitter 103 is 2.1 eV and the thickness is 4 nm;

[0061] A p-type microcrystalline silicon third emitter 104 is prepared on the p-type microcrystalline silicon oxygen second emitter 103 by using PECVD. The band gap width of the microcrystalline silicon oxygen third emitter 104 is 1.3 eV and the thickness is 5 nm.

[0062] In a third embodiment, an i / n composite resonant tunneling multilayer silicon film for a silicon heterojunction cell is provided, comprising the following steps:

[0063] An amorphous silicon passivation layer 101 is prepared on the cleaned and textured single crystal silicon textured substrate 100 by PECVD. The amorphous silicon passivation layer 101 is prepared by a two-step method. The bandgap widths of the amorphous silicon passivation layer 101 prepared by the two-step method are 1.85 eV and 1.9 eV, respectively, and the thicknesses are 1 nm and 3 nm, respectively.

[0064] On the passivation layer 101, an n-type microcrystalline silicon first emitter 102 is prepared by PECVD, and the band gap width of the microcrystalline silicon first emitter 102 is 1.4 eV and the thickness is 3 nm;

[0065] An n-type microcrystalline silicon oxygen second emitter 103 is prepared on the n-type microcrystalline silicon first emitter 102 by PECVD, and the band gap width of the microcrystalline silicon oxygen second emitter 103 is 1.7 eV and the thickness is 4 nm;

[0066] An n-type microcrystalline silicon third emitter 104 is prepared on the n-type microcrystalline silicon oxygen second emitter 103 by using PECVD. The band gap width of the microcrystalline silicon oxygen third emitter 104 is 1.3 eV and the thickness is 4 nm.

[0067] Through the above arrangement, a composite stacked film structure with resonant tunneling performance can be provided. Under the premise of maintaining a good surface passivation function, by designing the band structure and thickness of the composite film, a double barrier quantum well structure is formed in the emitter region of the heterojunction battery, which can significantly increase the tunneling probability of carriers and improve the carrier transport capacity of the silicon heterojunction battery, thereby improving the photoelectric conversion efficiency of the battery and solving the problem of poor carrier transport capacity of traditional amorphous silicon films.

[0068] On the other hand, when the above-mentioned resonant tunneling composite film is applied to a solar cell, an embodiment of the present application further discloses a solar cell, comprising any of the above-mentioned resonant tunneling composite films.

[0069] Specifically, it can be applied to silicon heterojunction and heterojunction perovskite stacked cells to improve the electrical transport performance of the batteries.

[0070] The solar cell has the same structure and beneficial effects as the resonant tunneling composite film in the above-mentioned embodiment. The structure and beneficial effects of the resonant tunneling composite film have been described in detail in the above-mentioned embodiment, and will not be repeated here.

[0071] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A resonant tunneling composite film, characterized in that: include: A substrate, and at least a passivation layer, a first emitter, a second emitter and a third emitter arranged in sequence on the substrate, the bandgap width of the passivation layer is greater than the bandgap width of the substrate, the bandgap width of the first emitter is smaller than the bandgap width of the passivation layer, the bandgap width of the second emitter is greater than the bandgap width of the first emitter, and the bandgap width of the third emitter is smaller than the bandgap width of the second emitter.

2. The resonant tunneling composite film according to claim 1, characterized in that: The bandgap width of the passivation layer is substantially equal to the bandgap width of the second emitter.

3. The resonant tunneling composite film according to claim 1, characterized in that: The bandgap width of the first emitter is substantially equal to the bandgap width of the third emitter.

4. The resonant tunneling composite film according to claim 1, characterized in that: The first emitter, the second emitter and the third emitter are all P-type emitters or all N-type emitters.

5. The resonant tunneling composite film according to claim 4, characterized in that: The Fermi energy level of the N-type emitter is higher than the Fermi energy level of the passivation layer; the Fermi energy level of the P-type emitter is lower than the Fermi energy level of the passivation layer.

6. The resonant tunneling composite film according to any one of claims 1 to 5, characterized in that: When the passivation layer is used as an N-surface, the conduction band bottom of the passivation layer is located above the conduction band bottom of the substrate, and the difference between the conduction band bottom of the passivation layer and the conduction band bottom of the substrate is not less than 0.4 eV; when the passivation layer is used as a P-surface, the valence band top of the passivation layer is located below the valence band top of the substrate, and the difference between the valence band top of the passivation layer and the valence band top of the substrate is not less than 0.4 eV, and the thickness of the passivation layer is less than 10 nm.

7. The resonant tunneling composite film according to any one of claims 1 to 5, characterized in that: When the first emitter is used as the N-surface, the conduction band bottom of the first emitter is below the conduction band bottom of the passivation layer, and the difference between the conduction band bottom of the first emitter and the conduction band bottom of the substrate is not higher than 0.2eV; when the first emitter is used as the P-surface, the valence band top of the first emitter is above the valence band top of the passivation layer, and the difference between the valence band top of the first emitter and the valence band top of the substrate is not higher than 0.2eV; the thickness of the first emitter is between 2nm and 10nm.

8. The resonant tunneling composite film according to any one of claims 1 to 5, characterized in that: When the second emitter is used as the N-surface, the conduction band bottom of the second emitter is above the conduction band bottom of the first emitter, and the difference between the conduction band bottom of the second emitter and the conduction band bottom of the substrate is not less than 0.4 eV; when the second emitter is used as the P-surface, the valence band top of the second emitter is below the valence band top of the first emitter, and the difference between the valence band top of the second emitter and the valence band top of the substrate is not less than 0.4 eV; the thickness of the second emitter is less than 10 nm.

9. The resonant tunneling composite film according to any one of claims 1 to 5, characterized in that: When the third emitter is used as the N-surface, the conduction band bottom of the third emitter is below the conduction band bottom of the second emitter, and the difference between the conduction band bottom of the third emitter and the conduction band bottom of the substrate is not higher than 0.4eV; when the third emitter is used as the P-surface, the valence band top of the third emitter is above the valence band top of the second emitter, and the difference between the valence band top of the third emitter and the valence band top of the substrate is not higher than 0.4eV; when the third emitter is used as the P-surface, the thickness of the third emitter is not less than 5nm.

10. A solar cell, characterized in that: It comprises the resonant tunneling composite film as claimed in any one of claims 1 to 9.

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