TBC battery, preparation method thereof and application of TBC battery in photovoltaic system

Abstract

The invention relates to the technical field of photovoltaics, and provides a TBC battery and a preparation method and application thereof in a photovoltaic system.The TBC battery comprises a first exciton fission material layer, a second exciton fission material layer and a third exciton fission material layer, the first exciton fission material layer is used for absorbing high-energy photons in an ultraviolet region and enhancing the separation efficiency of photon-generated carriers; the first packaging protection layer is located on the front face of the first exciton fission material layer, and the first packaging protection layer is made of hafnium nitric oxide modified by a hafnium-based metal organic framework. Through the synergistic effect of the two layers of structures, the photoelectric conversion efficiency of the formed TBC battery is improved by 15-20% compared with that of a conventional TBC battery, and the photoelectric conversion efficiency can reach 28% or above.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a TBC cell, its preparation method, and its application in photovoltaic systems. Background Technology

[0002] Tunneling Oxide Passivated BackContact (TBC) is a novel battery structure that combines Tunneling Oxide Passivated Contact (TOPCon) and Back Contact (BC) technologies, and it has the potential for high open-circuit voltage and high fill factor.

[0003] TBC batteries place all electrodes on the back of the battery, forming a back-contact structure. This design, which eliminates metal grid lines on the front, fundamentally eliminates the current loss caused by the blocking of incident light by the main and fine grid lines on the front of traditional batteries. This maximizes the effective light-receiving area and theoretically can achieve higher short-circuit current, laying a solid foundation for achieving ultra-high photoelectric conversion efficiency.

[0004] However, for TBC cells with a back-contact structure, the PN junction is located on the back side of the cell. High-energy ultraviolet light from sunlight (typically referring to wavelengths less than 400 nm) has a shallow penetration depth and is mainly absorbed near the light-receiving surface (front side) of the cell, generating photogenerated carriers. Since these carriers need to traverse the entire thickness of the silicon substrate to reach the PN junction on the back side for collection, the excessively long migration path significantly increases the probability of bulk or surface recombination. This limits further improvements in the photoelectric conversion efficiency of TBC cells.

[0005] To address the aforementioned technical challenges, several solutions have been proposed in existing technologies. For example, combining TBC cells with wide-bandgap perovskite solar cells to construct perovskite / crystalline silicon tandem cells. In this structure, the upper perovskite cell can specifically and efficiently absorb ultraviolet light and a portion of visible light, while the lower TBC cell is responsible for absorbing the remaining spectrum. Theoretically, this approach can achieve more comprehensive utilization of the solar spectrum. However, this approach also faces significant challenges: firstly, tandem cells have strict current matching requirements between the upper and lower sub-cells, resulting in an extremely narrow process window and high fabrication difficulty and cost; secondly, and more critically, perovskite materials themselves are extremely unstable under humid, hot, and light-exposed environments, easily undergoing decomposition and phase transitions, leading to rapid performance degradation in the short term. This makes it difficult to meet the long-term humid and hot reliability requirements of photovoltaic systems.

[0006] Therefore, there is an urgent need in this field for a solution that can not only significantly enhance the absorption and conversion capabilities of TBC cells for high-energy ultraviolet light, but also ensure that the cell structure has excellent long-term operational stability in order to meet the application requirements of photovoltaic power plants in various harsh environments. Summary of the Invention

[0007] This invention provides a TBC cell, its preparation method, and its application in photovoltaic systems, in order to overcome the aforementioned defects in the prior art and realize the TBC cell's ability to absorb and convert high-energy ultraviolet light as well as its excellent long-term working stability.

[0008] Specifically, in a first aspect, the present invention provides a TBC battery, comprising: The first exciton fission material layer is used to absorb high-energy photons in the ultraviolet region and enhance the separation efficiency of photogenerated carriers. The first encapsulation protective layer is located on the front side of the first exciton fission material layer, and the material of the first encapsulation protective layer is hafnium oxynitride modified with a hafnium-based metal-organic framework.

[0009] Unless otherwise specified, "front" in this invention refers to the same direction as the front of the TBC battery. "Back" in this invention refers to the same direction as the back of the TBC battery.

[0010] According to the TBC battery provided by the present invention, the first encapsulation protective layer is in direct contact with the first exciton fission material layer.

[0011] According to the TBC battery provided by the present invention, a hafnium oxide film is deposited on the surface of the first exciton fission material layer, and then the hafnium-based metal-organic framework is formed on the surface of the hafnium oxide film to obtain the first encapsulation protective layer.

[0012] According to the TBC battery provided by the present invention, the first exciton fission material layer is made of one or more of the following: benzene-based materials, bilayer WSe2, CdSe, and two-dimensional semiconductor materials.

[0013] According to the TBC battery provided by the present invention, the thickness of the first exciton fission material layer is 2~8 nm; And / or, the thickness of the first encapsulation protective layer is 2~6nm.

[0014] According to the TBC battery provided by the present invention, the TBC battery includes an N-type substrate; the front side of the N-type substrate includes, from the outside to the inside, an anti-reflection layer, a first encapsulation protective layer, a first exciton fission material layer, a first charge transfer layer and a passivation layer; the passivation layer is in direct contact with the N-type substrate.

[0015] According to the TBC cell provided by the present invention, the back side of the N-type substrate includes a tunneling oxide layer; the back side of the tunneling oxide layer includes N+ polycrystalline silicon structures and P+ polycrystalline silicon structures disposed at intervals.

[0016] According to the TBC battery provided by the present invention, a second charge transfer layer, a second exciton fission material layer, and a second encapsulation protection layer are sequentially disposed on the back side of the N+ polycrystalline silicon structure; the N+ polycrystalline silicon junction is in direct contact with the second charge transfer layer; And / or, a third charge transfer layer, a third exciton fission material layer, and a third encapsulation protection layer are sequentially disposed on the back side of the P+ polycrystalline silicon structure; the P+ polycrystalline silicon junction is in direct contact with the second charge transfer layer.

[0017] In a second aspect, the present invention also provides a method for preparing a TBC battery as described above, comprising: depositing a hafnium oxide thin film on a first exciton fission material layer.

[0018] Thirdly, the present invention also provides a photovoltaic system including a battery module, wherein the battery module includes a TBC battery as described above or a TBC battery prepared by the preparation method described above.

[0019] The TBC battery, its preparation method, and its application in photovoltaic systems provided by this invention, by setting a first encapsulation protective layer of a specific material on the front side of the first exciton fission material layer, utilizes the self-healing effect and intrinsic stability of the first encapsulation protective layer to ensure that the first exciton fission material layer fully absorbs high-energy photons in the ultraviolet region and enhances the separation efficiency of photogenerated carriers; through the synergistic effect of the above two-layer structure, the photoelectric conversion efficiency of the TBC battery is increased by 15-20% compared with conventional TBC batteries (i.e., those without the above two-layer structure), and the photoelectric conversion efficiency can reach more than 28%. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is one of the schematic diagrams of the TBC battery structure provided by the present invention.

[0022] Figure 2 This is the second schematic diagram of the TBC battery structure provided by the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] This invention first provides a TBC battery, comprising: The first exciton fission material layer is used to absorb high-energy photons in the ultraviolet region and enhance the separation efficiency of photogenerated carriers. The first encapsulation protective layer is located on the front side of the first exciton fission material layer, and the material of the first encapsulation protective layer is hafnium oxynitride modified with a hafnium-based metal-organic framework.

[0025] The first exciton fission material layer of this invention is used to absorb high-energy ultraviolet light and enhance the separation efficiency of photogenerated carriers. The working principle of this layer is as follows: when it absorbs a high-energy photon (such as ultraviolet light), it generates a high-energy singlet exciton. This singlet exciton can rapidly and efficiently "split" into two lower-energy triplet excitons, and its triplet energy is just higher than the band gap energy of crystalline silicon, which is ideal for coupling to crystalline silicon. Theoretically, this process can convert a high-energy photon into two pairs of usable carriers (electron-hole pairs), with a potential quantum efficiency of up to 200%. Simply put, while a traditional photon can generate one electron-hole pair, after passing through this material, a photon can generate two electron-hole pairs, significantly improving photon utilization.

[0026] The first encapsulation protective layer of this invention uses HfOyNx material modified with Hf-MOFs. This material has self-healing capabilities. When corroded by external factors such as moisture, its self-healing ability ensures the stable operation of the inner first exciton fission material layer (SF layer). Its self-healing mainly includes three mechanisms: 1. MOF adsorbs water molecules, and ligand hydrolysis generates H... + or OH - Ions; ions diffuse into the HfOyNx defect region, promoting surface hydroxylation reactions and inducing atomic regrowth. 2. After capturing water molecules in the environment, MOFs activate them through ligand functional groups (e.g., decomposing them into OH groups). - Or O 2- 3. Hf-MOFs act as ion channels, releasing or trapping Hf atoms. (The text then abruptly shifts to a seemingly unrelated topic about Hf-MOFs and their interaction with active sites on the HfOyNx surface, followed by a mention of Hf-MOFs as ion channels.) 4+ Ions migrate to lattice defects in HfOyNx and recover the defects through ion compensation.

[0027] In some embodiments of the present invention, the first encapsulation protective layer is in direct contact with the first exciton fission material layer.

[0028] In some embodiments of the present invention, a hafnium oxide film is deposited on the surface of the first exciton fission material layer, and then a hafnium-based metal-organic framework is formed on the surface of the hafnium oxide film to form the first encapsulation protective layer.

[0029] In some embodiments of the present invention, the material of the first exciton fission material layer is one or a combination of two or more of the following: benzene-based materials, bilayer WSe2, CdSe, and two-dimensional semiconductor materials.

[0030] The benzobenzene class includes one or more of benzotetrabenzene, benzopentabenzene, and benzohexabenzene.

[0031] In some embodiments of the present invention, the thickness of the first exciton fission material layer is 2~8 nm; And / or, the thickness of the first encapsulation protective layer is 2~6nm.

[0032] In some embodiments of the present invention, the TBC battery includes an N-type substrate; the front side of the N-type substrate includes, from the outside to the inside, an anti-reflection layer, a first encapsulation protective layer, a first exciton fission material layer, a first charge transfer layer and a passivation layer; the passivation layer is in direct contact with the N-type substrate.

[0033] The first charge transfer layer is used to rapidly separate and transfer electron-hole pairs; the energy level of the selected material should have a certain energy difference with that of the SF layer. Preferably, the material of the first charge transfer layer is selected from one or more combinations of materials such as NiPc, ZnPc, CuPc, NiOx, MoOx, and black phosphorus.

[0034] More preferably, the thickness of the first charge transfer layer is 1~5 nm.

[0035] This invention incorporates a first exciton fission material layer (SF layer) and its synergistic layer between the front passivation layer and the antireflection layer, including a first charge transfer layer, a first exciton fission material layer, and a first encapsulation protection layer. This achieves ultra-high utilization of high-energy ultraviolet light while the self-healing encapsulation protection layer improves the battery's damp-heat stability.

[0036] In some embodiments of the present invention, the back side of the N-type substrate includes a tunneling oxide layer; the back side of the tunneling oxide layer includes N+ polysilicon structures and P+ polysilicon structures disposed at intervals.

[0037] The N+ polycrystalline silicon structure is a phosphorus-doped polycrystalline silicon layer; wherein the phosphorus doping concentration is 1×10⁻⁶. 19 cm -3~1×10 20 cm -3 .

[0038] The P+ polycrystalline silicon structure is a boron-doped polycrystalline silicon layer; wherein the boron doping concentration is 1×10⁻⁶. 18 ~1×10 19 cm -3 .

[0039] In some embodiments of the present invention, a second charge transfer layer, a second exciton fission material layer, and a second encapsulation protective layer are sequentially disposed on the back side of the N+ polycrystalline silicon structure; the N+ polycrystalline silicon structure is in direct contact with the second charge transfer layer.

[0040] In some embodiments of the present invention, a third charge transfer layer, a third exciton fission material layer, and a third encapsulation protective layer are sequentially disposed on the back side of the P+ polycrystalline silicon structure; the P+ polycrystalline silicon structure is in direct contact with the second charge transfer layer.

[0041] The second charge transfer layer may be the same as or different from the first charge transfer layer, preferably the same.

[0042] The third charge transfer layer may be the same as or different from the first charge transfer layer, but preferably the same.

[0043] The second exciton fission material layer may be the same as or different from the first exciton fission material layer, preferably the same.

[0044] The third exciton fission material layer may be the same as or different from the first exciton fission material layer, preferably the same.

[0045] The second encapsulation protective layer may be the same as or different from the first encapsulation protective layer, preferably the same.

[0046] The third encapsulation protective layer may be the same as or different from the first encapsulation protective layer, preferably the same.

[0047] Considering the absorption of ultraviolet light reflected from the ground, the second exciton fission material layer and the second encapsulation protective layer of the present invention are applied to the back of the TBC battery.

[0048] Considering the insufficient ultraviolet light dose on the back side, it is preferable that the material of the second exciton fission material layer and / or the third exciton fission material layer is CdSe.

[0049] When the surface of the conventional TBC structure is provided with the above-mentioned structure, such as Figure 2 As shown, the corresponding metallization process must ensure that the electrode burns through the back encapsulation protective layer to guarantee current conduction. This battery structure improves photoelectric conversion efficiency by 15-20% compared to conventional TBC batteries without this structure.

[0050] The embodiments of the present invention also provide a method for preparing a TBC battery as described above, including depositing a hafnium oxide thin film on a first exciton fission material layer.

[0051] In some embodiments of the present invention, the preparation method of the TBC battery includes: using HfCl4, tetrakis(dimethylamino)hafnium, and NH3 as raw materials, depositing a hafnium oxide thin film on a first exciton fission material layer using PECVD. The PECVD process uses NH3 as a raw material, which, under plasma irradiation, can efficiently generate a large number of highly active N and H atoms, ions, and amino radicals. NH3 can not only react with hafnium precursor fragments to introduce nitrogen, but the H radicals can also contribute to the reduction reaction, potentially reducing chlorine residue introduced by HfCl4, thereby improving the film purity. The PECVD film preparation process is mature and has a fast deposition rate; optimized reaction chamber design can achieve film deposition with uniform thickness and composition.

[0052] In some embodiments of the present invention, the deposition of hafnium oxide thin films can also be carried out by PVD, using a metal target and employing magnetron sputtering and high-energy particle bombardment, while simultaneously introducing nitrogen and oxygen gases. However, this method is prone to generating pinholes, defects and damage in the thin film, resulting in poor electrical performance of the thin film and problems such as leakage.

[0053] In some embodiments of the present invention, ALD deposition can also be used, employing tetra(ethylmethylamide)hafnium, H2O, and NH3. By controlling the number of cycles and the ratio of these three substances, the hafnium oxide film can be regulated. However, the growth rate of ALD is very low, and the tetra(ethylmethylamide)hafnium reaction may produce byproducts such as HCl, which may contaminate the film or damage the equipment.

[0054] Therefore, using HfCl4, TDMAHf and NH3 as raw materials to deposit hafnium oxide thin films via PECVD technology has greater advantages.

[0055] In some embodiments of the present invention, the method for preparing the TBC battery includes: The hafnium-based metal-organic framework is uniformly coated onto the surface of the hafnium oxide film using a spin coating method, and then dried to obtain the first encapsulation protective layer.

[0056] In some embodiments of the present invention, the method for preparing the TBC cell includes: substrate pretreatment; preferably, the substrate pretreatment includes: selecting an N-type single crystal silicon wafer with a thickness of 100~150μm and a size of 182.2mm×210mm, and cleaning and flattening the surface of the silicon wafer by an alkaline polishing process, wherein the alkaline polishing process cleaning time is 200~300s.

[0057] In some embodiments of the present invention, the method for preparing the TBC cell includes: preparing B-doped P+ polycrystalline silicon; the preparation of the B-doped P+ polycrystalline silicon includes: depositing a tunneling oxide layer and intrinsic polycrystalline silicon on the back side of the substrate using a PECVD process, preparing B-doped P+ polycrystalline silicon by boron diffusion, and simultaneously forming a layer of BSG on the surface.

[0058] In some embodiments of the present invention, the method for preparing the TBC battery includes: laser grooving on the back side; the laser grooving on the back side includes: laser-cutting a predetermined N-type region of BSG, with an opening length of 0.5~3μm and a distance between two openings of 0.5~3μm.

[0059] In some embodiments of the present invention, the method for fabricating the TBC battery includes: BSG treatment; the BSG treatment includes: removing the front-side BSG with HF, then removing the P+ polycrystalline silicon around the substrate by alkaline etching, then texturing the front side, and fabricating a pyramid structure on the front side of the substrate.

[0060] In some embodiments of the present invention, the method for preparing the TBC cell includes: preparing P-doped N+ polycrystalline silicon; the preparation of P-doped N+ polycrystalline silicon includes: back-exposed P+ polycrystalline silicon, depositing a tunneling oxide layer and intrinsic polycrystalline silicon on the back side of the substrate using a PECVD process, preparing P-doped N+ polycrystalline silicon by P diffusion, and simultaneously forming a PSG layer on the surface.

[0061] In some embodiments of the present invention, the method for fabricating the TBC battery includes: PSG treatment; the PSG treatment includes: backside laser grooving, whereby the PSG in a predetermined P-type region is laser-cut. The front-side PSG is removed using HF, followed by alkaline etching to remove the N+ polysilicon around the substrate and the exposed N+ polysilicon on the backside.

[0062] In some embodiments of the present invention, the method for preparing the TBC battery includes: preparing a passivation layer; the preparation of the passivation layer includes: preparing 30-35 layers of aluminum oxide on the front side using an ALD (atomic layer deposition) process, with a thickness of 3.5-6 nm.

[0063] In some embodiments of the present invention, the method for preparing the TBC battery includes: preparing a charge transfer layer; taking NiPc material as an example, the preparation of the charge transfer layer includes: depositing NiPc molecules on the outside of the passivation layer by vacuum evaporation or chemical vapor deposition (CVD) to form a charge transfer layer with a thickness of 1~5nm, and controlling the process temperature at 200~600℃.

[0064] In some embodiments of the present invention, the method for preparing the TBC battery includes: preparing an exciton fission material layer; taking a bilayer WSe2 as an example, the preparation of the exciton fission material layer includes: using a CVD method, with tungsten and selenium sources as precursors, depositing a bilayer WSe2 thin film (WO3+3Se→WSe2+3 / 2O2) on the charge transfer layer, with a thickness of 2~8 nm. The temperature is controlled at 400~900℃, and the time is controlled at 30~90 min. The tungsten source is selected from WO3 and / or WCl6. The selenium source is Se powder.

[0065] In some embodiments of the present invention, the preparation method of the TBC battery includes: preparation of an encapsulation protective layer; the preparation of the encapsulation protective layer includes: using HfCl4, tetrakis(dimethylamino)hafnium, and NH3 as raw materials, depositing a hafnium oxide film on an exciton fission material layer by PECVD, with the thickness controlled at 2~6nm; uniformly coating a hafnium-based metal-organic framework on the surface of the hafnium oxide film by spin coating, and holding it at 150~200℃ for 10~60min in a muffle furnace under a nitrogen atmosphere.

[0066] In the preparation of the encapsulation protective layer of this invention, a hafnium oxide (HfOyNx) film is first prepared, and then a hafnium-based metal-organic framework (Hf-MOFs) is formed on it. This method is simpler and more conducive to industrial production. The hafnium-based metal-organic framework (Hf-MOFs) can be synthesized using a hydrothermal method. For example, using a solvothermal method, hafnium tetrachloride and an organic ligand are dissolved in an organic solvent, placed in a reaction vessel, and reacted at a temperature of 100-250°C to generate hafnium-based metal-organic frameworks (Hf-MOFs). The organic solvent is N,N-dimethylformamide (DMF) and acetonitrile in a volume ratio of 1:1-5. The organic ligand is terephthalic acid. The molar ratio of hafnium tetrachloride to the organic ligand is 1:1-3.

[0067] In the preparation of the encapsulation protective layer of the present invention, the encapsulation protective layer can also be a mixture material formed by simultaneously preparing HfOyNx and Hf-MOFs, specifically formed by hydrothermal method.

[0068] In some embodiments of the present invention, the method for preparing the TBC battery includes: preparing an antireflection layer; the preparation of the antireflection layer includes: depositing silicon nitride antireflection layers on the front and back sides using a PECVD method.

[0069] In some embodiments of the present invention, after forming the antireflective layer, the present invention may further include: a conventional metallization process on the back side to meet specific application requirements.

[0070] An embodiment of the present invention also provides a photovoltaic system, including a battery module, wherein the battery module includes a TBC battery as described above or a TBC battery prepared by the preparation method described above.

[0071] The battery assembly may also include a front glass, a front adhesive film, the TBC battery, a back adhesive film, a back glass, and an encapsulation frame.

[0072] The TBC battery and its preparation method of the present invention will be described in detail below with reference to specific implementation examples. Some abbreviations and their corresponding Chinese translations are as follows: PECVD: Plasma-enhanced chemical vapor deposition.

[0073] BSG: Borosilicate glass.

[0074] PSG: Phosphosilicate glass.

[0075] ALD: Atomic Layer Deposition CVD: Chemical Vapor Deposition HF: Hydrofluoric acid.

[0076] Preparation Example 1 A method for preparing hafnium-based metal-organic frameworks (MOFs) is described, comprising the following steps: Hafnium-based MOF materials are synthesized using a solvothermal method. 1 mol of a metal salt (hafnium tetrachloride) and 2 mol of an organic ligand (terephthalic acid) are dissolved in an organic solvent N,N-dimethylformamide (DMF) and an acetonitrile solvent at a volume ratio of 1:3. The mixture is placed in a reaction vessel and reacted at 200°C to generate hafnium-based MOF materials.

[0077] Example 1 This embodiment provides a TBC battery, such as Figure 1 As shown, its structure is as follows: N-type substrate; The back side of the N-type substrate is in direct contact with the tunneling oxide layer; the back side of the tunneling oxide layer is in direct contact with the N+ polysilicon structure and the P+ polysilicon structure that are spaced apart.

[0078] The front side of the N-type substrate consists of, from the outside to the inside, an anti-reflection layer, a first encapsulation protective layer, a first exciton fission material layer, a first charge transfer layer, and a passivation layer; the passivation layer is in direct contact with the N-type substrate.

[0079] The first exciton fission material layer is used to absorb high-energy photons in the ultraviolet region and enhance the separation efficiency of photogenerated carriers; the material of the first exciton fission material layer is a double-layer WSe2.

[0080] The first encapsulation protective layer is located on the front side of the first exciton fission material layer, and the material of the first encapsulation protective layer is hafnium oxynitride modified with a hafnium-based metal-organic framework. The first encapsulation protective layer is in direct contact with the first exciton fission material layer.

[0081] This embodiment also provides a method for preparing the above-mentioned TBC battery, the steps of which are as follows: (1) Substrate pretreatment; including: selecting an N-type single crystal silicon wafer with a thickness of 120μm and a size of 182.2mm×210mm, and cleaning and flattening the surface of the silicon wafer by alkaline polishing process, wherein the processing time of alkaline polishing process is 250s.

[0082] (2) Preparation of B-doped P+ polycrystalline silicon; including: depositing a tunneling oxide layer and intrinsic polycrystalline silicon on the back side of the substrate using PECVD process, and preparing B-doped P+ polycrystalline silicon by boron diffusion (the doping concentration of B is 0.5 × 10⁻⁶). 19 cm -3 ), and further form a layer of BSG on the surface.

[0083] (3) Backside laser grooving; including: laser cutting open a predetermined N-type region of BSG, with an opening length of 2μm and a distance of 2μm between the two openings.

[0084] (4) BSG treatment; including: removing the front side BSG with HF, then removing the P+ polysilicon around the substrate and the P+ polysilicon of the predetermined N-type region in step (3) by alkaline etching, then texturing the front side, and fabricating a pyramid structure on the front side of the substrate.

[0085] (5) Preparation of P-doped N+ polycrystalline silicon; including: N+ polycrystalline silicon with exposed back side, depositing a tunneling oxide layer and intrinsic polycrystalline silicon on the back side of the substrate using PECVD process, and preparing P-doped N+ polycrystalline silicon by P diffusion (P doping concentration is 0.5×10⁻⁶). 20 cm -3 At the same time, a layer of PSG is formed on the surface.

[0086] (6) PSG treatment; including: back laser grooving, laser cutting open the PSG in the predetermined P-type area. HF is used to remove the front PSG, followed by alkaline etching to remove the N+ polysilicon around the substrate and the exposed N+ polysilicon on the back.

[0087] (7) Passivation layer preparation; including: preparing 33 rings of aluminum oxide on the front side using ALD process, with a thickness of 4.5 nm.

[0088] (8) Preparation of charge transfer layer; taking NiPc material as an example, including: depositing NiPc molecules on the outside of the passivation layer by vacuum evaporation or CVD method, with a thickness of 3nm, to form a charge transfer layer, and controlling the process temperature at 300~500℃.

[0089] (9) Preparation of exciton fission material layer; taking bilayer WSe2 as an example, including: using CVD method, with tungsten source (WO3) and selenium source (Se powder) as precursors, depositing a bilayer WSe2 thin film with a thickness of 5nm on the charge transfer layer. The temperature is controlled at 600℃ and the time is controlled at 30min.

[0090] (10) Preparation of encapsulation protective layer; including: using HfCl4, tetra(dimethylamino)hafnium and NH3 as raw materials, a hafnium oxide film is deposited on the exciton fission material layer by PECVD method, with the thickness controlled at 2nm; the hafnium-based metal organic framework is uniformly coated on the surface of the hafnium oxide film by spin coating method, and the film is kept at 170℃ for 60min in a muffle furnace under nitrogen atmosphere.

[0091] (11) Preparation of antireflection layer; including: depositing silicon nitride antireflection layer on the front and back sides using PECVD method.

[0092] (12) Post-processing; including: conventional metallization process on the back side to meet specific application requirements.

[0093] Examples 2-5 This is essentially the same as Example 1, except for the thickness of the encapsulation protective layer. Details are shown in the table below: Table 1

[0094] Examples 6-10 This is essentially the same as Example 3, except for the material of the exciton fission material layer. Details are shown in the table below: Table 2

[0095] Example 11 This is basically the same as Example 3, except that: before the antireflection layer is prepared, such as... Figure 2 As shown, a second charge transfer layer, a second exciton fission material layer, and a second encapsulation protective layer are sequentially disposed on the back side of the N+ polycrystalline silicon structure; the N+ polycrystalline silicon is in direct contact with the second charge transfer layer; The back side of the P+ polycrystalline silicon structure is sequentially provided with a third charge transfer layer, a third exciton fission material layer, and a third encapsulation protective layer; the P+ polycrystalline silicon is in direct contact with the second charge transfer layer.

[0096] The second and third charge transfer layers have the same material and thickness as the first charge transfer layer.

[0097] The second and third exciton fission material layers have the same material and thickness as the first exciton fission material layer.

[0098] The second and third encapsulation protective layers have the same material and thickness as the first encapsulation protective layer.

[0099] Comparative Example 1 It is basically the same as Example 3, except that no encapsulation protective layer process is performed.

[0100] Test case The testing method is as follows: IV test: The prepared TBC battery is subjected to voltage scanning and current measurement under standard test conditions (usually irradiance of 1000W / m² and temperature of 25℃) using a solar simulator and a precision source meter, thereby plotting the IV curve and obtaining the battery conversion efficiency (η1).

[0101] Damp-heat cycling stability test: The prepared TBC cells were first subjected to IV test under standard conditions, and the initial cell conversion efficiency (η1) was recorded. The batch of cells were then placed in a constant temperature and humidity test chamber for damp-heat cycling stability test, with a temperature range of -40℃±2℃ to +85℃±2℃, for 50 cycles. The final electrical performance (η2) of the cells was then tested and compared with the previous test under standard conditions to determine the efficiency degradation (Δη).

[0102] The test results are as follows: Table 3

[0103] Solar cells with an encapsulation protective layer exhibit less efficiency degradation after damp heat cycling compared to those without. The choice of encapsulation material thickness and exciton multiplication material also influences cell efficiency. Adding bifacial exciton multiplication materials and encapsulation materials further improves efficiency and reliability.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A TBC battery, characterized in that, include: The first exciton fission material layer is used to absorb high-energy photons in the ultraviolet region and enhance the separation efficiency of photogenerated carriers. The first encapsulation protective layer is located on the front side of the first exciton fission material layer, and the material of the first encapsulation protective layer is hafnium oxynitride modified with a hafnium-based metal-organic framework.

2. The TBC battery according to claim 1, characterized in that, The first encapsulation protective layer is in direct contact with the first exciton fission material layer.

3. The TBC battery according to claim 1 or 2, characterized in that, The first encapsulation protective layer is obtained by depositing a hafnium oxide film on the surface of the first exciton fission material layer, and then forming the hafnium-based metal-organic framework on the surface of the hafnium oxide film.

4. The TBC battery according to any one of claims 1 to 3, characterized in that, The material of the first exciton fission material layer is one or a combination of two or more of the following: benzene-based materials, bilayer WSe2, CdSe, and two-dimensional semiconductor materials.

5. The TBC battery according to any one of claims 1 to 4, characterized in that, The thickness of the first exciton fission material layer is 2~8 nm; And / or, the thickness of the first encapsulation protective layer is 2~6nm.

6. The TBC battery according to any one of claims 1 to 5, characterized in that, The TBC cell includes an N-type substrate; The front side of the N-type substrate, from the outside to the inside, includes: an anti-reflection layer, a first encapsulation protective layer, a first exciton fission material layer, a first charge transfer layer, and a passivation layer. The passivation layer is in direct contact with the N-type substrate.

7. The TBC battery according to claim 6, characterized in that, The back side of the N-type substrate includes a tunneling oxide layer; the back side of the tunneling oxide layer includes N+ polysilicon structures and P+ polysilicon structures spaced apart.

8. The TBC battery according to claim 7, characterized in that, The back side of the N+ polycrystalline silicon structure is sequentially provided with a second charge transfer layer, a second exciton fission material layer, and a second encapsulation protective layer; the N+ polycrystalline silicon structure is in direct contact with the second charge transfer layer. And / or, a third charge transfer layer, a third exciton fission material layer, and a third encapsulation protection layer are sequentially disposed on the back side of the P+ polycrystalline silicon structure; the P+ polycrystalline silicon junction is in direct contact with the second charge transfer layer.

9. A method for preparing a TBC battery according to any one of claims 1 to 8, characterized in that, include: Hafnium oxide thin films are deposited on exciton fission material layers.

10. A photovoltaic system, characterized in that, The battery assembly includes a TBC battery according to any one of claims 1 to 8 or a TBC battery prepared by the preparation method according to claim 9.

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