Novel passivation selective contact structure and solar cell, assembly and system

Abstract

The invention discloses a novel passivation selective contact structure, a solar cell, an assembly and a system. The novel passivation selective contact structure comprises a silicon substrate, wherein the surface of the silicon substrate comprises a passivation selective contact area and a non-passivation selective contact area; the non-passivation selective contact area comprises a passivation anti-reflection layer arranged on the surface of the silicon substrate; the passivation selective contact area comprises a passivation layer, a selective transmission layer and a metal electrode which are sequentially stacked from inside to outside, the passivation layer covers a partial area of the surface of the silicon substrate, and the projection of the selective transmission layer on the surface of the silicon substrate covers a partial area of the surface of the silicon substrate. According to the invention, the passivation anti-reflection layer, the selective transmission layer and the passivation layer act synergistically, so that an excellent passivation contact effect is realized; and a narrow-band-gap highly-doped silicon material does not need to be used, so that the optical parasitic absorption loss is reduced, the photoelectric conversion efficiency is improved, and the performance of the solar cell is further improved.

Description

Technical Field

[0001] The present invention generally relates to the technical field of solar cells, and in particular to a novel passivation selective contact structure and solar cells, components and systems. Background Art

[0002] The current efficiency improvement of crystalline silicon solar cells faces the problem of p-region optimization. For example, in PERC and some p-type back contact (BC) cell designs, the p-region provides field effect passivation in the form of aluminum back field, but the passivation effect is poor (J0~600fA / cm 2 ), mainly due to the weak field passivation effect caused by the low doping concentration of aluminum back field and the severe Auger recombination loss. In addition, the local corrosion of the aluminum paste on the silicon substrate will increase the capture of carriers by metal-induced interface defects, which greatly restricts the V OC For cells based on p-type poly-Si (such as TOPCon and TOPCon-BC), there are difficulties in doping with boron and gallium, severe recombination losses caused by internal expansion, and optical parasitic absorption losses caused by high doping with narrow band gaps. For cells based on p-region boron hydride-doped amorphous silicon (a-Si:H) (such as silicon heterojunction SHJ), there are severe optical parasitic absorption losses, which restrict the short-circuit current (J SC Therefore, how to improve the passivation effect, reduce the recombination loss and suppress the optical parasitic absorption loss has a very important impact on improving the performance of solar cells. Summary of the invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, the present invention provides a novel passivation selective contact structure and solar cells, components and systems. The introduction of wide bandgap extremely high or extremely small work function materials or band-matching materials can significantly optimize carrier transport and passivation mechanisms. Compared with doped polysilicon or amorphous silicon, it can effectively avoid the serious optical parasitic absorption problem caused by narrow bandgap high doping concentration. Compared with aluminum back field, it avoids the damage caused by direct contact between metal and silicon substrate and the defect-induced recombination loss and Auger recombination loss caused by diffusion into the silicon substrate, thereby improving the passivation effect and improving the photoelectric conversion efficiency of solar cells and components.

[0004] In a first aspect, the present invention provides a novel passivation selective contact structure, comprising: a silicon substrate, the surface of the silicon substrate comprising a passivation selective contact region and a non-passivation selective contact region; The non-passivation selective contact region includes a passivation anti-reflection layer disposed on the surface of the silicon substrate; The passivation selective contact region includes a passivation layer, a selective transmission layer and a metal electrode which are stacked in sequence from the inside to the outside.

[0005] As an optional solution, based on the projection on the surface of the silicon substrate, the projection of the passivation layer covers a partial area of ​​the surface of the silicon substrate, and the projection of the selective transmission layer covers a partial area of ​​the surface of the silicon substrate; Alternatively, the projected area of ​​the passivation layer is greater than or equal to the projected area of ​​the selective transmission layer.

[0006] Alternatively, the projected area of ​​the selective transmission layer is greater than or equal to the projected area of ​​the metal electrode.

[0007] As an optional solution, the passivation anti-reflection layer includes aluminum oxide and silicon nitride layers stacked from the inside to the outside.

[0008] As an option, the thickness of the passivation layer is 0.1-300 nm.

[0009] As an optional solution, the passivation layer includes a first passivation layer and a second passivation layer, the selective transport layer includes a hole selective transport layer and / or an electron selective transport layer, the first passivation layer is arranged corresponding to the hole selective transport layer, and the second passivation layer is arranged corresponding to the electron selective transport layer.

[0010] As an optional scheme, the hole selective transport layer includes a hole selective layer, or a hole selective layer and a hole transport layer stacked from the inside to the outside, or a hole selective layer and an electron transport layer stacked from the inside to the outside; the electron selective transport layer includes an electron selective layer, or an electron selective layer and a hole transport layer stacked from the inside to the outside, or an electron selective layer and an electron transport layer stacked from the inside to the outside.

[0011] As an optional solution, the hole selection layer is selected from materials with a work function greater than 4.8 eV and a valence band gap ΔE V A material with a V of less than 0.5 eV, or a monomolecular layer material; the hole transport layer is selected from at least one of oxides, nitrides, oxynitrides, chalcogenides, halides, thiocyanates and organic conductive polymers; The electron selective layer is selected from materials with a work function less than 4.2 eV and a conduction band gap ΔE C <0.5eV material, or an organic conductive polymer; the electron transport layer is selected from at least one of doped or intrinsic oxides, nitrides, carbides, oxynitrides, carbon oxides, carbonitride oxides, chalcogenides, halides, or organic conductive polymers.

[0012] As an optional solution, the hole selection layer is selected from at least one of doped or intrinsic molybdenum oxide, vanadium oxide, tungsten oxide, chromium oxide, titanium oxide, copper oxide, nickel oxide, cobalt oxide, rhenium oxide, copper iodide, PEDOT:PSS, silicon carbide and a phosphate group monolayer; The hole transport layer is selected from at least one of doped or intrinsic nickel oxide, copper oxide, copper iodide, copper thiocyanate, thienyl, PEDOT:PSS, PTAA, Spiro-OMeTAD and fluorinated indoprofen derivatives; The electron selective layer is selected from at least one of doped or intrinsic lithium fluoride, magnesium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, cerium fluoride, europium fluoride, tantalum oxide, zinc oxide, indium oxide, titanium oxide, magnesium oxide, zinc oxide, tin oxide, cesium oxide, niobium oxide, barium oxide, tantalum nitride, titanium nitride, titanium oxynitride, silicon carbide, cesium chloride, cesium bromide, cesium iodide, cesium carbonate, potassium carbonate, rubidium carbonate, calcium carbonate, strontium carbonate, barium carbonate, zinc sulfide, cadmium sulfide, indium sulfide, fullerene derivatives and bathocuproine; The electron transport layer is selected from at least one of doped or intrinsic zinc oxide, indium oxide, tin oxide, titanium oxide, cadmium sulfide, cadmium selenide, fullerene derivatives and bathocuproine.

[0013] As an optional solution, the passivation layer is selected from at least one of silicon oxide, silicon oxynitride, aluminum oxide, phosphorus oxide, boron oxide, hafnium oxide, silicon carbide, titanium oxide, tin oxide, amorphous silicon, microcrystalline silicon and nanocrystalline silicon.

[0014] As an optional solution, the thickness of the hole selective transport layer is 0.1-700 nm, and the thickness of the passivation anti-reflection layer is 0-525 nm; Or, the thickness of the electron selective transport layer is 0.1-700nm In a second aspect, the present invention provides a solar cell comprising the novel passivation selective contact structure of the first aspect.

[0015] In a third aspect, the present invention provides a solar cell assembly, comprising a solar cell according to the second aspect.

[0016] In a fourth aspect, the present invention provides a solar cell system, comprising a solar cell assembly according to the third aspect.

[0017] The novel passivation selective contact structure of the present invention forms a strong built-in electric field by introducing a material with a higher work function or a material with a lower work function, or forms a strong built-in electric field by introducing a material that matches the energy band of the silicon substrate, thereby enhancing asymmetric carrier transport and separation, effectively enhancing carrier extraction and passivation capabilities, and improving the selectivity coefficient. The introduction of the passivation layer provides chemical and field effect passivation for the passivation selective contact area, suppresses interface defect states and eliminates the Fermi level pinning phenomenon, and provides a prerequisite for the excellent field passivation provided by the selective layer. The combination of the transport layer can compensate for the carrier transport difficulties caused by the large resistance of the selective layer, improve the fill factor, and is particularly suitable for local metallization structures. The additional chemical passivation gain of the passivation selective contact area can be further enhanced by introducing hydrogen, such as adopting a nitrogen-hydrogen mixed gas annealing (FGA) process. The superimposed passivation anti-reflection layer can provide more hydrogen passivation gain; thus, under the synergistic effect of the passivation layer, the selection layer, the transmission layer and the passivation anti-reflection layer, an excellent passivation contact effect is achieved; and there is no need to use narrow-bandgap highly doped silicon materials, which reduces optical parasitic absorption losses and jointly improves the photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 A schematic structural diagram of a novel passivation selective contact structure (P region structure) according to an embodiment of the present invention; Figure 2 for Figure 1 A partial enlarged view of A in the middle; Figure 3 for Figure 1 Another partial enlarged view of A in the middle; Figure 4 for Figure 1 Another partial enlarged view of A in the middle; Figure 5 A schematic structural diagram of another novel passivation selective contact structure according to an embodiment of the present invention ((N region structure)); Figure 6 is a schematic structural diagram of a battery in Example 1; Figure 7 is a schematic structural diagram of a battery in Example 2; Figure 8 is a schematic structural diagram of a battery in Example 3; Fig. 9 is a schematic structural diagram of a battery in Example 4; Fig.10 is a schematic structural diagram of a battery in Example 5; Fig.11 is a schematic structural diagram of a battery in Example 6; Fig.12 This is a schematic diagram of the structure of the battery of Example 7.

[0019] In the figure, 10. silicon substrate, 11. passivation anti-reflection layer, 111. aluminum oxide layer, 112. silicon nitride layer; 20. First passivation layer, 30. Hole selective transport layer, 31. Hole selection layer, 32. Transport layer, 40. First metal electrode, 50. Second passivation layer, 61. Electron selection layer, 70. Selective emitter, 80. Second metal electrode, 90. Tunneling oxygen layer, 91. Doped polysilicon layer, 92. Light expansion region. DETAILED DESCRIPTION

[0020] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] In related technologies, in order to improve the passivation effect, a hole selection layer is set to form field-effect passivation, thereby reducing the recombination loss of electrons and enhancing the hole extraction capability. However, simple field-effect passivation cannot significantly eliminate the interface defects with silicon, and a passivation layer is required to eliminate the Fermi level pinning phenomenon caused by interface defects and optimize the interface built-in electric field.

[0023] Based on the above problems, the embodiments of the present application provide a novel passivation selective contact structure, including: a silicon substrate 10, the surface of the silicon substrate 10 including a passivation selective contact region and a non-passivation selective contact region; The non-passivation selective contact region includes a passivation anti-reflection layer disposed on the surface of the silicon substrate 10; The passivation selective contact region includes a passivation layer, a selective transmission layer and a metal electrode which are sequentially stacked from the inside to the outside.

[0024] The back side of the silicon substrate refers to the backlight side, and the front side of the silicon substrate refers to the light-receiving side.

[0025] The novel passivation selective contact structure of the embodiment of the present application forms a strong built-in electric field by introducing a material with a higher work function or a material with a lower work function, or forms a strong built-in electric field by introducing a material that matches the energy band of the silicon substrate, thereby enhancing asymmetric carrier transport and separation, effectively enhancing carrier extraction and passivation capabilities, and improving the selectivity coefficient. The introduction of the passivation layer provides chemical and field effect passivation for the passivation selective contact area, suppresses interface defect states and eliminates the Fermi level pinning phenomenon, and provides a prerequisite for the excellent field passivation provided by the selective layer. The combination of the transport layer can compensate for the carrier transport difficulties caused by the large resistance of the selective layer, improve the filling factor, and is particularly suitable for local metallization structures. The additional chemical passivation gain of the passivation selective contact area can be further enhanced by introducing hydrogen, such as adopting a nitrogen-hydrogen mixed gas annealing (FGA) process. The superimposed passivation anti-reflection layer can provide more hydrogen passivation gain; thus, under the synergistic effect of the passivation layer, the selection layer, the transmission layer and the passivation anti-reflection layer, an excellent passivation contact effect is achieved; and there is no need to use narrow-bandgap highly doped silicon materials, which reduces optical parasitic absorption losses and jointly improves the photoelectric conversion efficiency.

[0026] As an achievable method, the passivation layer covers a part of the surface of the silicon substrate 10, and the projection of the selective transmission layer on the surface of the silicon substrate 10 covers a part of the surface of the silicon substrate 10, forming a local selective passivation contact structure, such as Figure 1 and Figure 5 shown.

[0027] The local selective passivation contact structure in this embodiment achieves an excellent passivation contact effect under the synergistic effect of the passivation anti-reflection layer, the passivation layer and the selective transmission layer.

[0028] like Figure 1 As shown, the back side of the silicon substrate 10 is stacked with a first passivation layer 20, a hole selection layer 31, a transmission layer 32, a passivation anti-reflection layer 11 and a first metal electrode 40 in sequence from the inside to the outside. The first metal electrode 40 passes through the passivation anti-reflection layer 11 and is in direct contact with the hole selection layer 31.

[0029] like Figure 5 As shown, a tunneling oxygen layer 90, a doped polysilicon layer 91, an electron selection layer 61, a passivation anti-reflection layer 11 and a second metal electrode 80 are sequentially stacked on the surface of the silicon substrate 10 from the inside to the outside. The second metal electrode 80 passes through the passivation anti-reflection layer 11 and contacts the electron selection layer 61. The projection of the electron selection layer 61 on the surface of the silicon substrate 10 covers a partial area of ​​the silicon substrate 10.

[0030] In a preferred embodiment, the passivation anti-reflection layer 11 includes an aluminum oxide layer 111 and a silicon nitride layer 112 stacked from the inside to the outside.

[0031] Among them, aluminum oxide and silicon nitride can both play a passivation role, and the anti-reflection effect mainly depends on silicon nitride; in a preferred embodiment, a multi-layer anti-reflection structure is set up, and silicon nitride can be set as a multi-layer silicon nitride layer with different refractive indexes; other anti-reflection layers, such as magnesium fluoride, can also be set on the silicon nitride surface.

[0032] In addition, silicon nitride may also be silicon nitride doped with oxygen, carbon, or both carbon and oxygen, that is, silicon oxynitride, silicon carbide nitride, silicon carbon nitride oxynitride, and the like.

[0033] In some embodiments, aluminum oxide may be replaced by intrinsic or doped amorphous silicon, nanocrystalline silicon, microcrystalline silicon, microcrystalline silicon oxide, nanocrystalline silicon oxide, amorphous silicon oxide, phosphorus oxide, boron oxide, hafnium oxide, silicon carbide, titanium oxide, gallium oxide, zinc oxide, or tantalum oxide.

[0034] As an achievable manner, the projection area of ​​the passivation layer is greater than or equal to the projection area of ​​the selective transmission layer based on the projection on the surface of the silicon substrate 10. This embodiment is conducive to ensuring a good passivation effect.

[0035] In a preferred embodiment, the passivation layer covers the entire surface of the silicon substrate 10 , and the projection of the selective transmission layer on the surface of the silicon substrate 10 covers a partial surface of the silicon substrate 10 .

[0036] It can also be understood that the projection of the passivation layer on the surface of the silicon substrate 10 covers the entire surface of the silicon substrate 10, and the projection of the selective transmission layer on the surface of the silicon substrate 10 covers the entire surface of the silicon substrate 10, forming a full-domain passivation selective contact structure.

[0037] In a preferred embodiment, the projection area of ​​the selective transmission layer is greater than or equal to the projection area of ​​the metal electrode based on the projection on the surface of the silicon substrate 10. That is, the metal electrode can fully or partially cover the selective transmission layer.

[0038] Since the selective transmission layer has high optical transmittance and high lateral conductivity, the projection area of ​​the metal electrode is as small as possible without affecting carrier transmission, which is conducive to ensuring higher photon utilization.

[0039] As an achievable manner, the thickness of the passivation layer is 0.1-300 nm.

[0040] In some embodiments, the passivation layer includes a first passivation layer 20 and a second passivation layer 50, the selective transport layer includes a hole selective transport layer 30 and / or an electron selective transport layer, the first passivation layer 20 is arranged corresponding to the hole selective transport layer 30, and the second passivation layer 50 is arranged corresponding to the electron selective transport layer.

[0041] Specifically, in some embodiments, the thickness of the first passivation layer 20 is 0.1-300 nm.

[0042] In some other embodiments, the thickness of the first passivation layer 20 is 0.1 nm-10 nm; in a preferred embodiment, the thickness of the first passivation layer 20 is 1.6 nm.

[0043] As an achievable manner, the passivation layer is at least one selected from silicon oxide, silicon oxynitride, aluminum oxide, phosphorus oxide, boron oxide, hafnium oxide, silicon carbide, titanium oxide, tin oxide, amorphous silicon, microcrystalline silicon and nanocrystalline silicon.

[0044] As a feasible manner, the hole selective transport layer 30 includes a hole selective layer 31, or a hole selective layer 31 and a hole transport layer stacked from the inside to the outside, or a hole selective layer 31 and an electron transport layer stacked from the inside to the outside; the electron selective transport layer includes an electron selective layer, or an electron selective layer and a hole transport layer stacked from the inside to the outside, or an electron selective layer and an electron transport layer stacked from the inside to the outside.

[0045] The electron transport layer and the hole transport layer may be collectively referred to as a transport layer 32 .

[0046] It is understandable that when the area ratio of the hole selection layer 31 to the metal electrode is not large, the transport layer can be omitted.

[0047] In some embodiments, the hole selection layer 31 is selected from materials with a work function greater than 4.8 eV and a valence band gap ΔE V A material with a V of less than 0.5 eV, or a monomolecular layer material; the hole transport layer is selected from at least one of oxides, nitrides, oxynitrides, chalcogenides, halides, thiocyanates and organic conductive polymers; The electron selective layer 61 is selected from materials with a work function less than 4.2 eV and a conduction band step ΔE C A material with a FET of less than 0.5 eV, or an organic conductive polymer; the electron transport layer is selected from at least one of doped or intrinsic oxides, nitrides, carbides, oxynitrides, carbon oxides, carbonitride oxides, chalcogenides, halides, or organic conductive polymers.

[0048] Specifically, the hole selection layer 31 is selected from at least one of doped or intrinsic molybdenum oxide, vanadium oxide, tungsten oxide, chromium oxide, titanium oxide, copper oxide, nickel oxide, cobalt oxide, rhenium oxide, copper iodide, PEDOT:PSS, silicon carbide and a phosphate group monolayer; The hole transport layers are each independently selected from at least one of doped or intrinsic nickel oxide, copper oxide, copper iodide, copper thiocyanate, thienyl, PEDOT:PSS, PTAA, Spiro-OMeTAD and fluorinated indoprofen derivatives; The electron selective layer 61 is selected from at least one of doped or intrinsic lithium fluoride, magnesium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, cerium fluoride, europium fluoride, tantalum oxide, zinc oxide, indium oxide, titanium oxide, magnesium oxide, zinc oxide, tin oxide, cesium oxide, niobium oxide, barium oxide, tantalum nitride, titanium nitride, titanium oxynitride, silicon carbide, cesium chloride, cesium bromide, cesium iodide, cesium carbonate, potassium carbonate, rubidium carbonate, calcium carbonate, strontium carbonate, barium carbonate, zinc sulfide, cadmium sulfide, indium sulfide, fullerene derivatives and bathocuproine; The electron transport layer is selected from at least one of doped or intrinsic zinc oxide, indium oxide, tin oxide, titanium oxide, cadmium sulfide, cadmium selenide, fullerene derivatives and bathocuproine.

[0049] Furthermore, the thickness of the hole selective transport layer 30 is 0.1 nm-700 nm, and the thickness of the passivation anti-reflection layer is 0 nm-525 nm.

[0050] In some embodiments, the electron selective transport layer has a thickness of 0.1 nm to 700 nm.

[0051] In a preferred embodiment, the thickness of the hole selective transport layer 30 is: 0.5 nm-340 nm; In a preferred embodiment, the thickness of the electron selective transport layer is 0.5 nm-340 nm; In a preferred embodiment, the thickness of the passivation anti-reflection layer 11 is 30 nm-300 nm.

[0052] In some embodiments, the thickness of the electron selective layer is 0.1 nm-100 nm, preferably 0.5 nm-40 nm; the thickness of the electron transport layer is 0 nm-600 nm, preferably 0 nm-300 nm.

[0053] It can also be understood that, due to the provision of the hole selective transport layer 30 and the electron selective transport layer 50 , the metal electrode can be made of low-cost metal, which is beneficial to greatly reduce the cost of metallization materials.

[0054] In some embodiments, the metal electrode includes a first metal electrode 40 and a second metal electrode 80, wherein the first metal electrode 40 can be a single-layer structure or a stacked structure, and the metal in contact with the hole selective output layer should be a metal material with a high work function. The stacked structure includes a seed layer, an intermediate layer and a protective layer; the seed layer is selected from a high work function metal (>4.2eV), and the thickness of the seed layer can be 0μm-50μm, preferably 5nm-1μm; the intermediate layer is selected from a high conductivity (>1×10 at 20°C) 17S / m) metal, the thickness of the intermediate layer can be 0μm-100μm, preferably 50 nm-20μm; the protective layer is selected from a metal with stable chemical properties, and the thickness of the protective layer can be 0μm-50μm, preferably 20nm-1μm; The second metal electrode 80 can be a single-layer structure or a laminated structure. The metal in contact with the electron selective transport layer should be a metal material with a low work function. The laminated structure includes a seed layer, an intermediate layer and a protective layer. The seed layer is selected from a metal with a low work function (<3.5 eV). The thickness of the seed layer can be 0-50 μm, preferably 5 nm-1 μm. The intermediate layer is selected from a metal with a high conductivity (>1×10 17 The thickness of the intermediate layer can be 0-100 μm, preferably 50 nm - 20 μm; the protective layer is selected from a metal with stable chemical properties, and the thickness of the protective layer can be 0-50 μm, preferably 20 nm - 1 μm.

[0055] For example, Figure 1 As shown, the back side of the silicon substrate is stacked with a first passivation layer 20, a hole selection layer 31, a transmission layer 32, a passivation anti-reflection layer 11 and a first metal electrode 40 from the inside to the outside. The first metal electrode 40 passes through the passivation anti-reflection layer 11 and directly contacts the hole selection layer 31. In order to show the overlapping relationship between different layers in the P-region slot area, as shown in FIG. Figure 2-4 As shown: the ideal situation is that the first passivation layer 20 and the hole selective transport layer 30 just cover the bottom surface of the grooved area and the sidewall of the groove, as shown in FIG. Figure 2 As shown, while ensuring a good passivation effect, since the passivation anti-reflection layer is not covered, a high double-sided rate is guaranteed; of course, considering the processing technology, the first passivation layer 20 and the hole selective transport layer 30 can also cover part of the passivation anti-reflection layer, but the covering area should be as small as possible, such as Figure 3 As shown. The grooved area may be formed from the passivation anti-reflection layer 11 to the surface of the silicon substrate 10 (eg Figure 4 As shown), of course, the grooved area can also extend into the interior of the silicon substrate 10 (as shown Figure 3 As shown), the embodiments of the present application do not specifically limit this.

[0056] In summary, the novel passivation selective contact structure of the present application forms a strong built-in electric field by introducing a material with a higher work function or a material with a lower work function, or forms a strong built-in electric field by introducing a material that matches the energy band of the silicon substrate, thereby enhancing asymmetric carrier transport and separation, effectively enhancing carrier extraction and passivation capabilities, and improving the selectivity coefficient. The introduction of the passivation layer provides chemical and field effect passivation for the passivation selective contact area, suppresses interface defect states and eliminates the Fermi level pinning phenomenon, and provides a prerequisite for the excellent field passivation provided by the selective layer. The combination of the transport layer can compensate for the carrier transport difficulties caused by the large resistance of the selective layer, improve the filling factor, and is particularly suitable for local metallization structures. The additional chemical passivation gain of the passivation selective contact area can be further enhanced by introducing hydrogen, such as adopting a nitrogen-hydrogen mixed gas annealing (FGA) process. The superimposed passivation anti-reflection layer can provide more hydrogen passivation gain; thus, under the synergistic effect of the passivation layer, the selection layer, the transmission layer and the passivation anti-reflection layer, an excellent passivation contact effect is achieved; and there is no need to use narrow-bandgap highly doped silicon materials, which reduces optical parasitic absorption losses and jointly improves the photoelectric conversion efficiency.

[0057] In a second aspect, an embodiment of the present application provides a solar cell, comprising the novel passivation selective contact structure of the first aspect. Thus, the solar cell has all the features and advantages of the novel passivation selective contact structure, which will not be described in detail here. In general, the solar cell has excellent cell performance.

[0058] The following is a specific example to illustrate the application of the novel passivation selective contact structure of the embodiment of the present application in various types of solar cells.

[0059] Example 1 like Figure 6 As shown, taking a p-type silicon substrate as an example, the silicon substrate 10 has a front side and a back side, the back side of the silicon substrate 10 includes a first passivation layer 20, a hole selection layer 31, a transmission layer 32, an aluminum oxide layer 111, a silicon nitride layer 112 and a first metal electrode 40 stacked from the inside to the outside on the back side of the silicon substrate 10, the first metal electrode is in contact with the transmission layer 32, the first passivation layer 20 covers a part of the surface of the silicon substrate 10, the hole selection layer 31 and the transmission layer cover the first passivation layer 20 and the projection on the surface of the silicon substrate covers a part of the surface of the silicon substrate; the front side of the silicon substrate 10 includes a selective emitter 70, a light diffusion layer 92, an aluminum oxide layer 111, a silicon nitride layer 112 and a second metal electrode 80 stacked from the inside to the outside on the surface of the silicon substrate 10, and the second metal electrode 80 passes through the silicon nitride layer 112 and the aluminum oxide layer 111 and contacts with the selective emitter 70.

[0060] Example 2 Different from Example 1, Figure 7As shown, the front side of the silicon substrate 10 includes a selective emitter 70, a light diffusion layer 92, an electron selection layer 61, an aluminum oxide layer 111, a silicon nitride layer 112 and a second metal electrode 80 stacked from inside to outside on the surface of the silicon substrate 10. The second metal electrode 80 passes through the silicon nitride layer 112 and the aluminum oxide layer 111 to contact the electron selection layer 61. The projection of the electron selection layer 61 on the surface of the silicon substrate 10 covers a partial area of ​​the surface of the silicon substrate 10.

[0061] It can be understood that in Embodiment 1 and Embodiment 2, both the front and back sides of the silicon substrate 10 are textured surfaces; the emitter on the front side can be a selective emitter or a non-selective emitter; at least one anti-reflection layer (ARC) can be disposed outside the silicon nitride layer, transmission layer or selection layer on the front and back sides of the silicon substrate; In addition, the above-mentioned battery can also be a back-junction battery, with the front side being a p-region and the back side being an n-region; or the silicon substrate can also be an n-type silicon substrate; the battery structure will not be specifically described here.

[0062] Furthermore, the front side of the silicon substrate in the above-mentioned battery is the local novel passivation selective contact structure in the above-mentioned embodiment 1, and the corresponding back side of the silicon substrate is the global passivation selective contact structure, that is, the projection of the electron selective layer on the surface of the silicon substrate covers the entire area of ​​the surface of the silicon substrate.

[0063] In Example 1 and Example 2, the aluminum back field in the PERC cell is replaced by the novel passivation selective contact structure of the embodiment of the present application, thereby avoiding direct contact between the metal and the silicon substrate, avoiding local heavy doping of the silicon substrate, reducing recombination losses, and using the strong built-in electric field formed by the work function difference of the non-doped silicon material itself, without introducing recombination losses caused by high doping; and the use of transmission materials with high transmittance and good transmission performance can effectively reduce the area ratio of the metal electrode, and the novel passivation selective contact structures all use high-transmittance materials with wide bandgap and low parasitic absorption, which can significantly improve the optical utilization rate of the back side.

[0064] Example 3 like Figure 8As shown, taking a p-type silicon substrate as an example, the silicon substrate 10 has a front side and a back side, and the front side and the back side of the silicon substrate 10 are respectively provided with a passivation selective contact region and a non-passivation selective contact region. Among them, the passivation selective contact region on the front side of the silicon substrate 10 includes a first passivation layer 20, a hole selection layer 31, a transmission layer 32 and a first metal electrode 40 stacked from the inside to the outside on the surface of the silicon substrate 10, and the projection of the first passivation layer 20 on the surface of the silicon substrate 10 covers a part of the surface of the silicon substrate 10; the non-passivation selective contact region includes an aluminum oxide layer 111 and a silicon nitride layer 112 stacked from the inside to the outside; the back side of the silicon substrate 10 includes a tunneling oxygen layer 90, a doped polysilicon layer 91, an aluminum oxide layer 111 and a silicon nitride layer 112, and a second metal electrode 80 stacked from the inside to the outside on the surface of the silicon substrate 10, and the second metal electrode 80 passes through the silicon nitride layer 112 and the aluminum oxide layer 111 and contacts the doped polysilicon layer 91.

[0065] Example 4 Different from Example 3, Fig. 9 As shown, the passivation selective contact region on the back of the silicon substrate 10 includes an electron selection layer 61 disposed on the doped polysilicon layer 91, the electron selection layer 61 covers a part of the doped polysilicon layer 91, the projection of the electron selection layer 61 on the surface of the silicon substrate 10 covers a part of the surface of the silicon substrate 10, and the second metal electrode 80 is in contact with the electron selection layer 61. Among them, the n-region doped polysilicon layer has a high selectivity, and the electron selection layer 61 is introduced on this basis to further improve the selectivity, so as to achieve the electron transmission by repelling holes; in actual processing, reducing the thickness of the doped polycrystalline layer is conducive to reducing the parasitic absorption of free carriers. In addition, under the coupling effect of the electron selection layer 61, the tunneling oxygen layer 90, the aluminum oxide layer 111 and the silicon nitride layer 112, the hydrogen elements in the aluminum oxide layer 111 and the silicon nitride layer 112 diffuse to the passivation selective contact surrounding area, improving the hydrogen passivation effect, thereby having good field effect passivation and chemical passivation effects.

[0066] It can be understood that the aluminum oxide layer and the silicon nitride layer in Embodiment 3 and Embodiment 4 can also be replaced or superimposed with at least one other anti-reflection layer, such as magnesium fluoride; It can also be understood that in the batteries of the above-mentioned Embodiments 3 and 4, the front side of the silicon substrate is the structure of the above-mentioned Embodiment 3, and the back side of the silicon substrate is a new type of passivation selective contact structure of the entire region, that is, the electron selective layer 61 covers the entire region of the doped polysilicon layer, and the projection of the electron selective layer 61 on the surface of the silicon substrate covers the entire region of the surface of the silicon substrate; In addition, Embodiment 3 and Embodiment 4 can also be applied to the tunneling oxygen polysilicon back field battery of N-type silicon substrate; for example, when the silicon substrate is an n-type silicon substrate and a p-type emitter 70 is used on the front side, the hole selective transport layer 30 is arranged on the p-type emitter 70, and the back side of the silicon substrate can be a stacked tunneling oxygen layer, a doped polysilicon layer, an aluminum oxide and silicon nitride layer and a first metal electrode 40; for another example, when the silicon substrate is an n-type silicon substrate and a p-type emitter 70 is used on the front side, the hole selective transport layer 30 is arranged on the p-type emitter 70, and the passivation selective contact area on the back side of the silicon substrate includes an electron selective layer 61, and the electron selective layer 61 is arranged on the doped polysilicon layer and covers a partial area of ​​the doped polysilicon layer. The projection of the electron selective layer 61 on the surface of the silicon substrate covers a partial area of ​​the surface of the silicon substrate. The embodiments of the present application do not describe the structure in detail.

[0067] In the above-mentioned Embodiment 3 and Embodiment 4, the material of the hole selection layer 31 can be either an n-type material or a p-type material. For a p-type silicon substrate or a p-type emitter, if the material of the hole selection layer 31 is n-type, an electron transport layer is used; if the material of the hole selection layer 31 is p-type, the material of the transport layer 32 can be either p-type or n-type, which can be selected according to the actual structure.

[0068] In Examples 3 and 4, the new passivation selective contact structure replaces the boron-doped polysilicon layer or the aluminum back field structure, avoiding the problem of composite losses caused by the highly doped region; and the new passivation selective contact structure has low optical parasitic absorption losses and can be used in conjunction with a non-burn-through metallization process, thereby eliminating the risk of burn-through of the n-region doped polysilicon layer, allowing the thickness of the doped polysilicon layer in the n-region to be thinned, thereby reducing the optical parasitic absorption losses caused by the doped polysilicon in the n-region.

[0069] Example 5 like Fig.10As shown, taking a p-type silicon substrate as an example, the silicon substrate 10 has a front side and a back side, the front side of the silicon substrate 10 includes an aluminum oxide layer 111 and a silicon nitride layer 112 stacked from the inside to the outside on the surface of the silicon substrate, and the back side of the silicon substrate 10 includes a plurality of first regions and a plurality of second regions distributed at intervals, each of the first region and each of the second regions respectively includes a non-passivation selective contact region and a passivation selective contact region, the non-passivation selective contact region includes an aluminum oxide layer 111 and a silicon nitride layer 112 stacked from the inside to the outside on the surface of the silicon substrate, and the passivation selective contact region of the first region includes a first passivation layer 2 stacked from the inside to the outside on the surface of the silicon substrate 0, a hole selection layer 31, a transport layer 32 and a second metal electrode 80; the passivation selective contact area of ​​the second region includes a tunneling oxide layer 90, a doped polysilicon layer 91 and a second metal electrode 80 stacked from the inside to the outside on the surface of the silicon substrate 10, an aluminum oxide layer 111 and a silicon nitride layer 112 cover the doped polysilicon layer 91, and the second metal electrode 80 contacts the doped polysilicon layer 91 through the silicon nitride layer 112 and the aluminum oxide layer 111; wherein the first passivation layer 20 covers the entire surface of the silicon substrate 10 located in the first region, and the projection of the hole selection layer 31 on the silicon substrate 10 covers the entire surface of the silicon substrate 10 located in the first region.

[0070] Example 6 Different from Example 5, Fig.11 As shown, the first passivation layer 20 covers a portion of the surface of the silicon substrate 10 located in the first region, and a projection of the hole selection layer 31 on the silicon substrate 10 covers a portion of the surface of the silicon substrate 10 located in the first region.

[0071] Example 7 The difference from Example 6 is that Fig.12 As shown, the passivation selective contact area of ​​the second region also includes a second passivation layer 50 and an electron selection layer 61 stacked on the doped polysilicon layer 91, and the second metal electrode 80 sequentially passes through the silicon nitride layer 111 and the aluminum oxide layer 112 to contact the electron selection layer 61, and the projection of the electron selection layer 61 on the doped polysilicon layer 91 covers part of the doped polysilicon layer 91.

[0072] In a third aspect, the embodiments of the present application provide a solar cell assembly, including a solar cell according to the second aspect. It is understandable that the solar cell assembly has all the features and advantages of the above-mentioned solar cells, which will not be described in detail here. In general, the solar cell assembly has a high cell efficiency.

[0073] In a fourth aspect, an embodiment of the present application provides a solar cell system, including a solar cell assembly according to the third aspect. It is understandable that the solar cell system has all the features and advantages of the above-mentioned solar cell, which will not be repeated here. In general, the solar cell system has a higher cell efficiency.

[0074] It should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used above to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0075] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A new type of passivation selective contact structure, It is characterized in that include: A silicon substrate, wherein a surface of the silicon substrate includes a passivation selective contact region and a non-passivation selective contact region; The non-passivation selective contact region comprises a passivation anti-reflection layer disposed on the surface of the silicon substrate; The passivation selective contact region comprises a passivation layer, a selective transmission layer and a metal electrode which are sequentially stacked from the inside to the outside.

2. The novel passivation selective contact structure according to claim 1, It is characterized in that Based on the projection on the surface of the silicon substrate, the projection of the passivation layer covers a partial area of ​​the surface of the silicon substrate, and the projection of the selective transmission layer covers a partial area of ​​the surface of the silicon substrate; Or, the projected area of ​​the passivation layer is greater than or equal to the projected area of ​​the selective transmission layer; Alternatively, the projected area of ​​the selective transmission layer is greater than or equal to the projected area of ​​the metal electrode.

3. The novel passivation selective contact structure according to claim 1, It is characterized in that The passivation anti-reflection layer includes aluminum oxide and silicon nitride layers stacked from inside to outside.

4. The novel passivation selective contact structure according to claim 1, It is characterized in that The thickness of the passivation layer is 0.1-300 nm.

5. The novel passivation selective contact structure according to any one of claims 1 to 4, It is characterized in that The passivation layer includes a first passivation layer and a second passivation layer, the selective transport layer includes a hole selective transport layer or an electron selective transport layer, the first passivation layer is arranged corresponding to the hole selective transport layer, and the second passivation layer is arranged corresponding to the electron selective transport layer.

6. The novel passivation selective contact structure according to claim 5, It is characterized in that The hole selective transport layer includes a hole selective layer, or a hole selective layer and a hole transport layer stacked from the inside to the outside, or a hole selective layer and an electron transport layer stacked from the inside to the outside; The electron selective transport layer includes an electron selective layer, or an electron selective layer and a hole transport layer stacked from the inside to the outside, or an electron selective layer and an electron transport layer stacked from the inside to the outside.

7. The novel passivation selective contact structure according to claim 5, It is characterized in that The hole selection layer is selected from materials with a work function greater than 4.8 eV and a valence band gap ΔE V A material with a V of less than 0.5 eV, or a monomolecular layer material; the hole transport layer is selected from at least one of oxides, nitrides, oxynitrides, chalcogenides, halides, thiocyanates and organic conductive polymers; The electron selective layer is selected from materials with a work function less than 4.2 eV and a conduction band step ΔE C A material with a FET of less than 0.5 eV, or an organic conductive polymer; the electron transport layer is selected from at least one of doped or intrinsic oxides, nitrides, carbides, oxynitrides, carbon oxides, carbonitride oxides, chalcogenides, halides, or organic conductive polymers.

8. The novel passivation selective contact structure according to claim 7, It is characterized in that The hole selection layer is selected from at least one of doped or intrinsic molybdenum oxide, vanadium oxide, tungsten oxide, chromium oxide, titanium oxide, copper oxide, nickel oxide, cobalt oxide, rhenium oxide, copper iodide, PEDOT:PSS, silicon carbide and a phosphate group monolayer; The hole transport layer is selected from at least one of doped or intrinsic nickel oxide, copper oxide, copper iodide, copper thiocyanate, thienyl, PEDOT:PSS, PTAA, Spiro-OMeTAD and fluorinated indoprofen derivatives; The electron selective layer is selected from at least one of doped or intrinsic lithium fluoride, magnesium fluoride, potassium fluoride, rubidium fluoride, cesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, cerium fluoride, europium fluoride, tantalum oxide, zinc oxide, indium oxide, titanium oxide, magnesium oxide, zinc oxide, tin oxide, cesium oxide, niobium oxide, barium oxide, tantalum nitride, titanium nitride, titanium oxynitride, silicon carbide, cesium chloride, cesium bromide, cesium iodide, cesium carbonate, potassium carbonate, rubidium carbonate, calcium carbonate, strontium carbonate, barium carbonate, zinc sulfide, cadmium sulfide, indium sulfide, fullerene derivatives and bathocuproine; The electron transport layer is selected from at least one of doped or intrinsic zinc oxide, indium oxide, tin oxide, titanium oxide, cadmium sulfide, cadmium selenide, fullerene derivatives and bathocuproine.

9. The novel passivation selective contact structure according to claim 1, It is characterized in that The passivation layer is selected from at least one of silicon oxide, silicon oxynitride, aluminum oxide, phosphorus oxide, boron oxide, hafnium oxide, silicon carbide, titanium oxide, tin oxide, amorphous silicon, microcrystalline silicon and nanocrystalline silicon.

10. The novel passivation selective contact structure according to claim 5, It is characterized in that The thickness of the hole selective transport layer is 0.1-700 nm, and the thickness of the passivation anti-reflection layer is 0-525 nm; Alternatively, the thickness of the electron selective transport layer is 0.1-700 nm.

11. A solar cell, It is characterized in that The invention comprises the novel passivation selective contact structure as described in any one of claims 1 to 10.

12. A solar cell module, It is characterized in that A solar cell comprising the solar cell described in claim 11.

13. A solar cell system, It is characterized in that A solar cell module comprising the solar cell module as claimed in claim 12.

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