Photovoltaic cell capable of continuously generating power day and night and preparation method thereof

Abstract

The invention provides a photovoltaic cell capable of continuously generating power day and night and a preparation method, and belongs to the technical field of photovoltaic power generation, the photovoltaic cell comprises a silicon substrate, a passivation layer and an antireflection film layer are sequentially arranged on the front surface and / or the back surface of the silicon substrate from inside to outside, and a fluorescent quantum layer is further arranged on the front surface and / or the back surface of the silicon substrate; and the fluorescent quantum layer is hidden on the inner side of the antireflection film layer, is positioned between the antireflection film layer and the passivation layer or between the passivation layer and the silicon substrate, and is in direct contact with the front surface and / or the back surface of the silicon substrate. According to the photovoltaic cell capable of continuously generating power day and night provided by the invention, the fluorescent quantum layer is prepared in the photovoltaic cell, and the fluorescent quantum layer is hidden below the antireflection film layer, so that the fluorescent quantum layer not only can normally transmit solar rays in the daytime, but also can absorb part of redundant light rays for storage; at night or when light is insufficient, the photovoltaic cell can continuously generate power through afterglow of the fluorescence effect, and the stability of day and night power supply is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar power generation, and in particular relates to a photovoltaic cell capable of continuously generating electricity day and night and a preparation method thereof. Background Art

[0002] Photovoltaic cells, also known as photovoltaic effect solar cells, are a type of photoelectric conversion device based on semiconductor materials. Its core function is to directly convert sunlight into electrical energy, a process that does not require combustion or other chemical processes, so it is clean and pollution-free.

[0003] The power generation efficiency of photovoltaic cells is affected by many factors, the most significant of which is the intensity of light. As the energy source of photovoltaic cells, changes in the intensity of sunlight directly determine the power generation capacity of the cells. During clear days, the sunlight is strong, and photovoltaic cells can efficiently convert light energy into electrical energy. However, when encountering cloudy days, haze, rain and snow and other weather conditions, the intensity of sunlight will be greatly reduced, resulting in a significant decrease in the power generation efficiency of photovoltaic cells. In addition, as the position of the sun moves during the day, changes in the angle of light will also affect the power generation efficiency of photovoltaic cells. At night, due to the lack of sunlight, photovoltaic cells cannot carry out the photoelectric conversion process, and therefore cannot generate electricity, which also makes the photovoltaic power generation system unable to provide electricity at night, resulting in unstable power supply during the day and night.

[0004] To sum up, the shortcomings of photovoltaic cell power generation are: the power generation efficiency of photovoltaic cells is greatly affected by light intensity. When there is insufficient light or at night, photovoltaic cells cannot generate electricity normally, resulting in unstable power supply. Summary of the invention

[0005] The embodiments of the present invention provide a photovoltaic cell that continuously generates electricity day and night and a preparation method thereof, aiming to solve the problem of unstable power supply day and night due to insufficient sunlight during the day or failure of photovoltaic cells to generate electricity normally at night.

[0006] In a first aspect, to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a photovoltaic cell that generates electricity continuously day and night, comprising: a silicon substrate, the front and / or back sides of the silicon substrate are provided with a passivation layer and an anti-reflection film layer in sequence from the inside to the outside, and the front and / or back sides of the silicon substrate are also provided with a fluorescent quantum layer; the fluorescent quantum layer is hidden on the inner side of the anti-reflection film layer, located between the anti-reflection film layer and the passivation layer, or located between the passivation layer and the silicon substrate, and directly contacts the front and / or back sides of the silicon substrate.

[0007] In combination with the first aspect, in one achievable manner, the thickness of the fluorescent quantum layer is 10 nm-100 nm.

[0008] In combination with the first aspect, in one achievable manner, the structure of the fluorescent quantum layer is a dense structure or a pore network structure.

[0009] In a second aspect, an embodiment of the present invention further provides a method for preparing a photovoltaic cell that continuously generates electricity day and night, which is used to prepare the photovoltaic cell that continuously generates electricity day and night, and the method comprises: depositing a fluorescent quantum layer on the surface of the silicon substrate by physical vapor deposition; the physical vapor deposition comprises any one of evaporation deposition, sputtering deposition or ion beam deposition; An anti-reflection film layer is deposited on the fluorescent quantum layer.

[0010] In conjunction with the second aspect, in an achievable manner, the fluorescent quantum layer is deposited on the surface of the silicon substrate by using the evaporation deposition, including: Inserting the silicon substrate on a quartz boat, pushing it into a vacuum chamber, and purging and cleaning the vacuum chamber; Regulating the vacuum pressure in the vacuum chamber; preheating the silicon substrate; The fluorescent material suspension is placed in an evaporation boat or a crucible and heated to evaporate, and the formed vapor is passed into the vacuum chamber and deposited on the surface of the silicon substrate to form the fluorescent quantum layer.

[0011] In combination with the second aspect, in an achievable manner, the silicon substrate on which the fluorescent quantum layer is deposited is subjected to an annealing treatment to adjust the microscopic morphology of the fluorescent quantum layer; When the fluorescent quantum layer is annealed at a low temperature of 200-600° C., a dense structure is formed; When the fluorescent quantum layer is annealed at a high temperature of 500-1000° C., a pore network structure is formed.

[0012] In combination with the second aspect, in one achievable manner, the temperature for heating and evaporating the fluorescent material suspension is 1000-1500°C.

[0013] In combination with the second aspect, in one achievable manner, the distance between the outlet through which the steam enters the vacuum chamber and the silicon substrate is 100-300 mm.

[0014] In conjunction with the second aspect, in one achievable manner, the fluorescent quantum layer is deposited on the surface of the silicon substrate by sputtering deposition, comprising: The radio frequency power supply is turned on to ionize the Ar gas to generate plasma. The Ar+ ions in the plasma bombard the target material synthesized by the fluorescent material. The sputtered atoms are deposited on the surface of the silicon substrate to form the fluorescent quantum layer. The sputtering power is 100-500W and the deposition time is 10-30min.

[0015] In combination with the second aspect, in one achievable manner, the fluorescent material used in the fluorescent quantum layer is any one of strontium europium aluminate, zinc sulfide doped with copper or silver, zinc oxide doped with aluminum, gallium or indium, calcium aluminate doped with europium or dysprosium, calcium silicate doped with europium and dysprosium, strontium silicate doped with europium, lanthanum oxide doped with europium, yttrium oxide, neodymium oxide, europium oxide, and dysprosium oxide doped with europium.

[0016] The photovoltaic cell and preparation method for continuous power generation day and night provided by the present invention have the following beneficial effects compared with the prior art: the present invention prepares the fluorescent quantum layer inside the photovoltaic cell. During the preparation process of the photovoltaic cell, the fluorescent quantum layer is grown on a silicon substrate and is hidden under the anti-reflection film layer. In addition to being able to normally transmit sunlight during the day, the fluorescent quantum layer also absorbs and stores some excess light. At night or when there is insufficient light, the stored photons can be released through the afterglow of fluorescence, and then continue to provide photons to the cell substrate to stimulate carrier transmission. The photovoltaic cell can continuously generate electricity day and night, ensuring the stability of power supply day and night. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the basic structure of the current TOPCon battery; Figure 2 This is a schematic diagram of the basic structure of the current HJT battery; Figure 3 A schematic diagram of the structure of a TOPCon photovoltaic cell with a fluorescent quantum layer prepared in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a HJT photovoltaic cell with a fluorescent quantum layer prepared in an embodiment of the present invention; Description of reference numerals: 1. Silicon substrate; 2. Tunneling SiOx layer; 3. Doped polysilicon layer; 4. Back silicon nitride layer; 5. Back electrode; 6. Emitter; 7. Aluminum oxide layer; 8. Front silicon nitride layer; 9. Front electrode; 10. Fluorescent quantum layer; 11. Back intrinsic hydrogenated amorphous silicon; 12. N-type hydrogenated amorphous silicon; 13. Back transparent conductive layer; 14. Front intrinsic hydrogenated amorphous silicon; 15. P-type hydrogenated amorphous silicon; 16. Front transparent conductive layer. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] Please also read Figure 3 and Figure 4, the preparation method of the photovoltaic cell that continuously generates electricity day and night provided by the present invention is now described. The preparation method of the photovoltaic cell that continuously generates electricity day and night comprises: a silicon substrate 1, a passivation layer and an anti-reflection film layer are sequentially arranged on the front and / or back of the silicon substrate 1 from the inside to the outside, and a fluorescent quantum layer 10 is also arranged on the front and / or back of the silicon substrate 1; the fluorescent quantum layer 10 is hidden inside the anti-reflection film layer, located between the anti-reflection film layer and the passivation layer, or located between the passivation layer and the silicon substrate 1, and directly contacts the front and / or back of the silicon substrate 1.

[0020] Compared with the prior art, the photovoltaic cell for continuous power generation during the day and night provided by the present invention has the following beneficial effects: the present invention prepares the fluorescent quantum layer inside the photovoltaic cell, grows the fluorescent quantum layer 10 on the silicon substrate 1 during the preparation of the photovoltaic cell, and hides the fluorescent quantum layer 10 under the anti-reflection film layer. In addition to being able to normally transmit sunlight during the day, the fluorescent quantum layer 10 also absorbs some excess light and stores it; at night or when the light is insufficient, the stored photons can be released through the afterglow of the fluorescence effect, and then continue to provide photons for the cell substrate, stimulate carrier transmission, and the photovoltaic cell can continuously generate electricity during the day and night, ensuring the stability of the power supply during the day and night. The fluorescent quantum layer 10 is hidden under the anti-reflection film layer to prevent the afterglow from escaping, and can make all the photons generated by the afterglow enter the silicon substrate 1, increase the utilization rate of the afterglow, and improve the power generation effect of the photovoltaic cell at night or when the light is insufficient.

[0021] It should be noted that although fluorescent technology is used to improve the power generation efficiency at night or in low light conditions in the current photovoltaic power generation field, it is achieved by using fluorescent glass or applying a film on the glass to achieve power generation at night or in low light conditions. Since glass and film are transparent materials, the fluorescent substances on them will scatter into the environment when releasing afterglow, causing waste of afterglow and reduced fluorescence efficiency. Moreover, when a large-area photovoltaic array releases afterglow at the same time, it will cause obvious light pollution and affect the surrounding ecology.

[0022] The present invention directly manufactures the fluorescent quantum layer inside the battery and covers the outer anti-reflection film layer, which can not only solve the problem of photovoltaic cells continuously generating electricity at night or in low light conditions, but also avoid the light pollution and afterglow waste of fluorescent components. Therefore, the present invention prepares the fluorescent quantum layer inside the battery for the first time and hides it under the anti-reflection film layer, which can release the afterglow at night and under low light conditions, so that the photovoltaic cell can continue to generate electricity, and will not release the afterglow into the environment, so it will not cause light pollution and damage the ecology. Moreover, the released afterglow all enters the interior of the photovoltaic cell, and the afterglow power generation efficiency is high. The fluorescent material is selected from a material with a long afterglow duration, which can ensure sufficient power generation time.

[0023] The photovoltaic cell prepared by the present invention can be a single-sided cell or a double-sided cell. When the photovoltaic cell is a single-sided cell, only one side receives light to generate electricity. At this time, it is only necessary to prepare the fluorescent quantum layer 10 on the front or back side of the silicon substrate 1. When the photovoltaic cell is a double-sided cell, both the front and back sides of the photovoltaic cell can perform photoelectric conversion. At this time, it is necessary to prepare the fluorescent quantum layer 10 on both the front and back sides of the silicon substrate 1.

[0024] The single-sided or double-sided cells with the fluorescent quantum layer 10 prepared above are connected in series using welding ribbons, and are packaged with glass, adhesive film, and frames to form photovoltaic modules, which are finally installed in the power generation system. It can realize power generation by using sunlight during sunny days, and power generation by using the afterglow released by the fluorescent quantum layer at night or when there is insufficient light, thereby achieving the effect of continuous power generation day and night, and ensuring the stability of power supply of the day and night power generation system.

[0025] Moreover, the fluorescent quantum layer 10 only needs to be hidden inside the anti-reflection film layer, and can be prepared between the anti-reflection film layer and the passivation layer, or can be directly made on the silicon substrate and directly contact the front and back sides of the silicon substrate.

[0026] At present, there are two main typical photovoltaic cell structures. One is the TOPCon cell (tunneling oxide passivation contact cell), which has a structure like Figure 1 As shown; the other is the HJT battery (intrinsic thin film heterojunction battery), whose structure is as follows Figure 2 shown.

[0027] See also Figure 1 At present, this TOPCon cell includes a silicon substrate 1, and the front side of the silicon substrate 1 is provided with an emitter 6, an aluminum oxide layer 7, a front silicon nitride layer 8 and a front electrode 9 in sequence from the inside to the outside; the back side of the silicon substrate 1 is provided with a tunneling SiOx layer 2, a doped polysilicon layer 3, a back silicon nitride layer 4 and a back electrode 5 in sequence from the inside to the outside; wherein, the emitter 6 and the aluminum oxide layer 7 are front passivation layers, and the tunneling SiOx layer 2 and the doped polysilicon layer 3 are back passivation layers; the front silicon nitride layer 8 and the back silicon nitride layer 4 are anti-reflection film layers on the front and back sides of the silicon substrate 1.

[0028] When a fluorescent quantum layer 10 is prepared on both the front and back surfaces of this TOPCon battery, on the front side of the battery, the fluorescent quantum layer 10 can be prepared between the emitter 6 and the aluminum oxide layer 7, or between the aluminum oxide layer 7 and the front silicon nitride layer 8, or between the silicon substrate 1 and the emitter 6; similarly, on the back side of the battery, the fluorescent quantum layer 10 can be prepared between the tunneling SiOx layer 2 and the doped polysilicon layer 3, or between the doped polysilicon layer 3 and the back silicon nitride layer 4, or between the tunneling SiOx layer 2 and the silicon substrate 1.

[0029] like Figure 3As shown, in the TOPCon photovoltaic cell provided by the present invention, the front side of the silicon substrate 1 is provided with an emitter 6, an aluminum oxide layer 7, a fluorescent quantum layer 10 (front side), a front silicon nitride layer 8 and a front electrode 9 in sequence from the inside to the outside; the back side of the silicon substrate 1 is provided with a tunneling SiOx layer 2, a doped polysilicon layer 3, a fluorescent quantum layer 10 (back side), a back silicon nitride layer 4 and a back electrode 5 in sequence from the inside to the outside.

[0030] It should be noted that in the present invention, the thickness of the fluorescent quantum layer 10 on the front side and the fluorescent quantum layer 10 on the back side may be different, and the microstructure shapes may also be different.

[0031] See also Figure 2 At present, this type of HJT battery includes a silicon substrate 1, and the front side of the silicon substrate 1 includes, from the inside to the outside, a front intrinsic hydrogenated amorphous silicon 14, a P-type hydrogenated amorphous silicon 15, a front transparent conductive layer 16 and a front electrode 9; the back side of the silicon substrate 1 includes, from the inside to the outside, a back intrinsic hydrogenated amorphous silicon 11, an N-type hydrogenated amorphous silicon 12, a back transparent conductive layer 13, and a back electrode 5; wherein, the front intrinsic hydrogenated amorphous silicon 14 and the P-type hydrogenated amorphous silicon 15 are the front passivation layers, the back intrinsic hydrogenated amorphous silicon 11 and the N-type hydrogenated amorphous silicon 12 are the back passivation layers, and the front transparent conductive layer 16 and the back transparent conductive layer 13 are anti-reflection film layers on both the front and back sides.

[0032] When the fluorescent quantum layer 10 is prepared on both the front and back sides of this HJT battery, on the front side of the battery, the fluorescent quantum layer 10 can be prepared between the silicon substrate 1 and the front intrinsic hydrogenated amorphous silicon 14, or between the front intrinsic hydrogenated amorphous silicon 14 and the P-type hydrogenated amorphous silicon 15, or between the P-type hydrogenated amorphous silicon 15 and the front transparent conductive layer 16; on the back side of the battery, the fluorescent quantum layer 10 can be prepared between the silicon substrate 1 and the back intrinsic hydrogenated amorphous silicon 11, or between the back intrinsic hydrogenated amorphous silicon 11 and the N-type hydrogenated amorphous silicon 12, or between the N-type hydrogenated amorphous silicon 12 and the back transparent conductive layer 13.

[0033] See also Figure 4 In the HJT photovoltaic cell prepared by the present invention, the fluorescent quantum layer 10 on the front side of the cell is prepared between the P-type hydrogenated amorphous silicon 15 and the front transparent conductive layer 16, and the fluorescent quantum layer 10 on the back side of the cell is prepared between the N-type hydrogenated amorphous silicon 12 and the back transparent conductive layer 13.

[0034] The stability of the fluorescent quantum layer is discussed as follows: (1) When the fluorescent quantum layer is combined with aluminum oxide (Al 2 O 3 ) After direct contact with the substrate, oxygen bridging bonds and ionic bonds will be formed, thereby ensuring the stability of the fluorescent quantum layer deposition.

[0035] Oxygen bridging bonds: The oxygen atoms in the strontium europium aluminate film can form oxygen bridging bonds (O-Al-O) with the aluminum atoms in the alumina substrate.

[0036] Ionic Bonding: Ionic bonding is possible between strontium (Sr) in strontium europium aluminate and oxygen (O) in the alumina matrix because strontium is a divalent cation and oxygen is a divalent anion.

[0037] (2) When the fluorescent quantum layer and silicon oxide (SiO 2 ) When the substrate is in direct contact, silicon-oxygen covalent bonds and silicon-oxygen covalent bonds are formed.

[0038] Silicon-oxygen covalent bonds: The oxygen atoms in the strontium-europium aluminate film can form covalent bonds (Si-O) with the silicon atoms in the silicon oxide substrate.

[0039] Silicon-oxygen covalent bonds: If hydrogen atoms are present, hydrogen bonds may form, especially when there are hydroxyl groups (-OH) on the surface of the film and the substrate.

[0040] (3) When the fluorescent quantum layer is combined with silicon nitride (Si 3 N 4 ) When the anti-reflection film layers are in direct contact, nitrogen bridging bonds and ionic bonds are formed.

[0041] Nitrogen bridging bonds: Oxygen atoms in the strontium europium aluminate film may form nitrogen bridging bonds (O-Si-N) with nitrogen atoms in the silicon nitride substrate.

[0042] Ionic Bond: Strontium ions can form ionic bonds with nitrogen atoms in silicon nitride.

[0043] The formation of the above chemical bonds can ensure the stable existence of the fluorescent quantum layer.

[0044] The terms involved in the present invention are explained as follows: Transparent conductive layer, also known as TCO, refers to a transparent conductive electrode, which is a component formed by uniformly coating a transparent conductive oxide film on the surface of flat glass.

[0045] Fluorescence: Fluorescence is a photoluminescent phenomenon that occurs when certain substances (fluorescent materials) absorb high-energy light (usually ultraviolet or visible light) and immediately re-emit it at a longer wavelength. This process is usually accompanied by a short time delay and the intensity of the emitted light is lower than the absorbed light.

[0046] Afterglow: refers to the phenomenon that some materials can continue to emit light for a period of time after the irradiation stops. Afterglow materials are also called light-storing materials or long afterglow materials. They can slowly release light energy after absorbing light energy.

[0047] The method for preparing a photovoltaic cell that continuously generates electricity day and night provided in an embodiment of the present invention specifically prepares a fluorescent quantum layer in a photovoltaic cell, and the preparation process of the fluorescent quantum layer needs to be selected according to the physical and chemical properties of the material. The present invention takes strontium europium aluminate as a fluorescent material and prepares a fluorescent quantum layer on a silicon substrate 1 as an example, and physical vapor deposition (PVD) can be used for preparation, and physical vapor deposition (PVD) includes any one of evaporation deposition, sputtering deposition and ion beam deposition.

[0048] The embodiment of depositing the fluorescent quantum layer 10 on the surface of the silicon substrate 1 by evaporation deposition in physical vapor deposition (PVD) is as follows: The working principle of evaporation deposition is to heat the fluorescent material to make it evaporate, and then the vapor is deposited on the silicon substrate to form a thin film; the required equipment is a PVD vacuum deposition furnace.

[0049] The process of evaporation deposition is as follows: Step 1: insert the silicon substrate 1 into a quartz boat. Depending on the capacity of the equipment, each boat can hold 150-600 pieces.

[0050] Step 2: Push the quartz boat into the vacuum chamber of the deposition furnace, close the furnace door and lock it.

[0051] Step three: fill with nitrogen and purge the chamber.

[0052] Step 4: Turn on the vacuum pump and reduce the pressure in the vacuum chamber to a suitable working pressure (usually 10 - 6 Torr).

[0053] Step 5: Preheating to remove moisture from the surface of the silicon substrate and increase adhesion. The preheating temperature is generally 150-250℃.

[0054] Step 6: Place the strontium-europium aluminate suspension in an evaporation boat or crucible, and heat the evaporation boat using resistance heating or electron beam heating. The resulting vapor is passed into the vacuum chamber and deposited on the surface of the silicon substrate 1 to form a fluorescent quantum layer 10. The heating rate should be adjusted according to the thermal stability of the material to avoid overheating and decomposition of the material.

[0055] Evaporation parameter settings: Evaporation temperature: Determined by the melting point and vapor pressure of strontium europium aluminate, usually 1000-1500°C.

[0056] Evaporation time: Calculated based on the required film thickness and evaporation rate, usually 15-30 minutes.

[0057] The distance between the quartz boat and the steam outlet into the vacuum chamber is usually 100-300mm.

[0058] The strontium aluminate europium material evaporates at high temperature, and the thin film formed by the condensation of the vapor on the surface of the silicon substrate is the fluorescent quantum layer. The thickness of the film is adjusted by controlling the evaporation time and temperature. The thickness of the prepared fluorescent quantum layer can be 10nm-100nm, but is not limited to this value. When it is made into a dense structure, its thickness should be thinner than the pore structure.

[0059] Step seven, close the evaporation chamber and perform annealing on the photovoltaic cell after the fluorescent quantum layer 10 is deposited to control the change of the microscopic morphology of the layer; wherein, low temperature annealing (200-600°C) can form a dense structure, and high temperature annealing (above 500-1000°C) can form a porous network structure.

[0060] Step eight, turn off the heating source, cool naturally or use a cooling system to quickly lower the temperature of the vacuum chamber, and take out the silicon substrate 1 on which the fluorescent quantum layer 10 is deposited.

[0061] The embodiment of depositing the fluorescent quantum layer 10 on the surface of the silicon substrate 1 by sputtering deposition is as follows: The working principle of sputtering deposition is that high-energy particles are used to bombard the target material, sputtering the target atoms and depositing them on the silicon substrate.

[0062] Required equipment: PVD vacuum deposition furnace.

[0063] The process of sputtering deposition is as follows: Step 1: insert the silicon substrate 1 into a quartz boat. Depending on the capacity of the equipment, each boat can hold 150-600 pieces.

[0064] Step 2: Push the quartz boat into the vacuum chamber of the deposition furnace, close the furnace door and lock it.

[0065] Step three: fill with nitrogen and purge the chamber.

[0066] Step 4: Turn on the vacuum pump and reduce the pressure in the vacuum chamber to a suitable working pressure (usually 10 - 6 Torr).

[0067] Step 5: preheating to remove moisture from the surface of the silicon substrate 1 and increase adhesion. The preheating temperature is generally 150-250°C.

[0068] Step 6: Use the pre-synthesized strontium aluminate europium target. Turn on the RF power supply to ionize the Ar gas to generate plasma. + Ions bombard the target material, sputtering out strontium europium aluminate atoms, which migrate and deposit on the surface of the silicon substrate to form a thin film, which is the fluorescent quantum layer.

[0069] Sputtering parameter settings: Ar gas flow rate: usually 20-80sccm.

[0070] The distance between the target and the quartz boat is usually 50-200mm.

[0071] Sputtering power: adjusted according to the target material and the required film thickness, usually 100-500W.

[0072] Deposition time: calculated based on the required film thickness and deposition rate, usually 10-30 minutes.

[0073] Step 7: Turn off the RF power supply and Ar gas, and perform annealing on the photovoltaic cell after the fluorescent quantum layer 10 is deposited to control the change of the microscopic morphology of the layer. Low temperature annealing (200-600°C) can form a dense structure, and high temperature annealing (above 500-1000°C) can form a pore network structure (generally a pinhole-shaped pore network structure).

[0074] Step eight, turn off the heating source, cool naturally or use a cooling system to quickly lower the temperature of the deposition chamber, and take out the silicon substrate 1 on which the fluorescent quantum layer 10 is deposited.

[0075] An embodiment of depositing the fluorescent quantum layer 10 on the surface of the silicon substrate 1 by ion beam deposition is as follows: How ion beam deposition works: A beam of ions is used to deposit material onto a substrate.

[0076] Required equipment: PVD vacuum deposition furnace.

[0077] The process of ion beam deposition is as follows: Step 1: insert the silicon substrate 1 into a quartz boat. Depending on the capacity of the equipment, each boat can hold 150-600 pieces.

[0078] Step 2: Push the quartz boat into the vacuum chamber of the deposition furnace, close the furnace door and lock it.

[0079] Step three: fill with nitrogen and purge the chamber.

[0080] Step 4: Turn on the vacuum pump and reduce the pressure in the vacuum chamber to a suitable working pressure (usually 10 - 6 Torr).

[0081] Step 5: Preheating to remove moisture from the surface of the silicon substrate 1 and increase adhesion. The preheating temperature is generally 150-250°C. (Steps 1 to 5 are the same in the above three preparation processes) Step six, placing the strontium europium aluminate material into a target material near the ion source, and using an ion gun to generate a high-energy ion beam. Argon is usually used as the working gas, and the parameters of the ion gun (such as voltage and current) are adjusted to generate the desired ion beam.

[0082] Ion beam parameter settings: Ion energy: usually in the range of several hundred to several thousand electron volts (eV), typically 400-2000 eV.

[0083] Ion beam density: adjusted according to the desired film growth rate.

[0084] Deposition time: Calculated based on the required film thickness and ion beam density, usually 10-20 minutes.

[0085] The ion beam bombards the target material, sputtering out strontium europium aluminate atoms or molecules, which are deposited on the surface of the silicon substrate 1 to form a thin film, namely the fluorescent quantum layer 10. The thickness of the film can be adjusted by controlling the deposition time and the ion beam current density.

[0086] Step 7: turn off the ion gun, stop the ion beam bombardment, and perform annealing on the photovoltaic cell after the fluorescent quantum layer 10 is deposited to control the change of the microscopic morphology of the layer. Low temperature annealing (200-600°C) can form a dense structure, and high temperature annealing (above 500-1000°C) can form a mesh structure. The aperture of the mesh structure is generally the size of a pinhole.

[0087] Step 8: Turn off the heating source, cool naturally or use the cooling system to quickly lower the temperature of the deposition chamber, and take it out.

[0088] After preparing the fluorescent quantum layer on the surface of the silicon substrate, if a single-sided battery is required, the fluorescent quantum layer on the back and sides of the battery can be removed by mask etching, corrosion cleaning and other means, and the fluorescent quantum layer on the side of the battery can also be left intact.

[0089] The fluorescent quantum layer is prepared by physical vapor deposition (PVD), which has the following characteristics: Composite target design: Composite targets are used, which contain pre-synthesized strontium europium aluminate materials to ensure accurate stoichiometric ratios during deposition. Usually, pure element targets are required to prepare silicon nitride, aluminum oxide, and silicon oxide films.

[0090] Active doped targets: Design targets containing active europium doping to optimize the luminescence properties of thin films by controlling the doping concentration.

[0091] Atmosphere modulation deposition: Dynamically adjust the ratio of oxygen and nitrogen during the deposition process to promote the formation of oxides and improve the film structure. The deposition of aluminum oxide and silicon oxide needs to be carried out in an oxygen or vacuum environment, while the deposition of silicon nitride needs to be carried out in a nitrogen atmosphere, that is, both are regulated by a single environment atmosphere.

[0092] The purpose of annealing is different: the annealing of the fluorescent quantum layer is to promote the improvement of crystallization and luminescence performance and improve the microscopic morphology, while the annealing of silicon nitride, aluminum oxide and silicon oxide film layers is to reduce stress, improve structure or enhance adhesion.

[0093] Other feasible preparation methods such as chemical vapor deposition (CVD), atomic layer deposition (ALD), solution method, sol-gel method, electrochemical deposition, thermal spraying, laser ablation, etc. can also realize the preparation of fluorescent quantum layers in photovoltaic cells.

[0094] The raw materials for the fluorescent quantum layer of the present invention should be mainly materials that can emit light continuously, i.e., materials with a long afterglow (the afterglow can last for several hours). Usually, they include but are not limited to the following materials: Strontium Europium Aluminate (SrAl 2 O 4 Eu); Zinc sulfide (ZnS): usually doped with copper (Cu) or silver (Ag) to produce green or blue luminescence effects, and the doping amount is not limited; Zinc oxide (ZnO): can be doped with different metal ions, such as aluminum, gallium or indium, with no limit on the doping amount; Calcium aluminate (CaAl 2 O 4 ): doped with europium (Eu) or dysprosium (Dy), the doping amount is not limited; Calcium silicate (CaSiO 3 ): doping with europium and dysprosium, the doping amount is not limited; Strontium silicate (SrSiO 3 ): doped with europium, the doping amount is not limited; Lanthanum oxide (La 2 O 3 ): doping with europium or other rare earth elements, the doping amount is not limited; Yttrium oxide (Y 2 O 3 ): doping with europium or other rare earth elements, the doping amount is not limited; Neodymium oxide (Nd 2 O 3 ): used in laser materials and optical devices; Europium oxide (Eu 2 O 3 ); Dysprosium oxide 2 O 3 ).

[0095] Aluminate long afterglow luminescent materials have excellent properties such as high luminous brightness, long afterglow time, stable performance, no radiation and no pollution, and have broad application prospects. Strontium europium dysprosium aluminate is one of them. At present, the high temperature solid phase method is used to synthesize strontium europium dysprosium aluminate luminescent materials.

[0096] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A photovoltaic cell that generates electricity continuously day and night, comprising: A silicon substrate (1), wherein a passivation layer and an anti-reflection film layer are sequentially arranged on the front and / or back of the silicon substrate (1) from the inside to the outside, characterized in that a fluorescent quantum layer (10) is also arranged on the front and / or back of the silicon substrate (1); the fluorescent quantum layer (10) is hidden on the inner side of the anti-reflection film layer, located between the anti-reflection film layer and the passivation layer, or located between the passivation layer and the silicon substrate (1), and directly contacts the front and / or back of the silicon substrate (1).

2. The photovoltaic cell for continuous power generation day and night as claimed in claim 1, characterized in that: The thickness of the fluorescent quantum layer (10) is 10nm-100nm.

3. The photovoltaic cell for continuous power generation day and night as claimed in claim 1, characterized in that: The structure of the fluorescent quantum layer (10) is a dense structure or a pore network structure.

4. A method for preparing a photovoltaic cell that continuously generates electricity day and night, for preparing the photovoltaic cell that continuously generates electricity day and night as claimed in any one of claims 1 to 3, characterized in that: The method comprises: depositing a fluorescent quantum layer (10) on the surface of the silicon substrate (1) by physical vapor deposition; the physical vapor deposition comprises any one of evaporation deposition, sputtering deposition or ion beam deposition; An anti-reflection film layer is deposited on the fluorescent quantum layer (10).

5. The method for preparing a photovoltaic cell capable of continuously generating electricity day and night as claimed in claim 4, characterized in that: Depositing a fluorescent quantum layer (10) on the surface of the silicon substrate (1) by using the evaporation deposition method comprises: Inserting the silicon substrate (1) on a quartz boat, pushing it into a vacuum chamber, and purging and cleaning the vacuum chamber; Regulating the vacuum pressure in the vacuum chamber; Preheating the silicon substrate (1); The fluorescent material suspension is placed in an evaporation boat or a crucible and heated to evaporate, and the generated vapor is passed into a vacuum chamber and deposited on the surface of the silicon substrate (1) to form the fluorescent quantum layer (10).

6. The method for preparing a photovoltaic cell capable of continuously generating electricity day and night as claimed in claim 5, characterized in that: Annealing the silicon substrate (1) on which the fluorescent quantum layer (10) is deposited, so as to adjust the microscopic morphology of the fluorescent quantum layer (10); When the fluorescent quantum layer (10) is annealed at a low temperature of 200-600° C., a dense structure is formed; When the fluorescent quantum layer (10) is annealed at a high temperature of 500-1000° C., a pore network structure is formed.

7. The method for preparing a photovoltaic cell capable of continuously generating electricity day and night as claimed in claim 5, characterized in that: The temperature for heating and evaporating the fluorescent material suspension is 1000-1500°C.

8. The method for preparing a photovoltaic cell capable of continuously generating electricity day and night as claimed in claim 5, characterized in that: The distance between the outlet of the steam entering the vacuum chamber and the silicon substrate (1) is 100-300 mm.

9. The method for preparing a photovoltaic cell capable of continuously generating electricity day and night as claimed in claim 4, characterized in that: Depositing the fluorescent quantum layer (10) on the surface of the silicon substrate (1) by sputtering deposition comprises: Turn on the RF power supply to ionize the Ar gas to generate plasma. + Ions bombard a target material synthesized from a fluorescent material, and the sputtered atoms are deposited on the surface of the silicon substrate to form the fluorescent quantum layer; wherein the sputtering power is 100-500W, and the deposition time is 10-30min.

10. The method for preparing a photovoltaic cell capable of continuously generating electricity day and night as claimed in claim 4, characterized in that: The fluorescent material used in the fluorescent quantum layer (10) is any one of strontium europium aluminate, zinc sulfide doped with copper or silver, zinc oxide doped with aluminum, gallium or indium, calcium aluminate doped with europium or dysprosium, calcium silicate doped with europium and dysprosium, strontium silicate doped with europium, lanthanum oxide doped with europium, yttrium oxide, neodymium oxide, europium oxide and dysprosium oxide doped with europium.

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