Novel method for improving performance of crystalline silicon solar cell by using UV light

Abstract

The invention discloses a novel method for improving the performance of a crystalline silicon solar cell by using UV light, and relates to the technical field of solar cells. The method comprises the following steps: S1, taking a finished battery, and reserving current and voltage data of the finished battery; s2, the finished solar cell is placed in a UV light source device, a light source is used for irradiating the front face of the finished solar cell, the distance between the light source and the finished solar cell ranges from 0.01 mm to 500 mm, the power of the light source ranges from 0.01 kW / m < 2 > to 50 kW / m < 2 >, and the duration time ranges from 0.01 s to 20 s; and S3, current and voltage testing is carried out, and data before UV irradiation are compared. According to the method, the efficiency of the crystalline silicon solar cell is improved by about 0.07% through UV irradiation, the power generation capacity of the solar cell can be directly improved, the method for improving the performance of the crystalline silicon solar cell through UV irradiation has a remarkable efficiency improvement effect, and especially in the aspects of the open-circuit voltage, the filling factor and the overall efficiency of the cell, the efficiency of the solar cell is improved. The performance of the solar cell can be optimized in multiple aspects, and the market competitiveness of the solar cell is expected to be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a novel method for improving the performance of crystalline silicon solar cells using UV light. BACKGROUND

[0002] Crystalline silicon solar cells, as the most widely used type of solar cells, have high efficiency and stability, making them dominant in the photovoltaic field. However, despite the many advantages of crystalline silicon solar cells, their conversion efficiency and cost remain a bottleneck restricting their widespread application. Especially under low light intensity, the photoelectric conversion efficiency of crystalline silicon solar cells is low, and due to surface defects and carrier recombination, the performance of solar cells has not yet reached its potential maximum level.

[0003] Existing methods for improving the efficiency of crystalline silicon solar cells, such as surface passivation, spectral tuning, and the application of high-efficiency reflective films, can improve cell performance to some extent, but still have the following limitations: (1) Limited light absorption capacity: Traditional crystalline silicon solar cells can only absorb visible light and part of the infrared light, which makes their efficiency lower under low light conditions.

[0004] (2) Surface defect problem: Defect states on the surface of crystalline silicon material can cause carrier recombination, severely affecting the photoelectric conversion efficiency of the cell. Although existing surface passivation techniques can effectively reduce this problem, they cannot completely eliminate the impact of surface defects.

[0005] (3) Insufficient light utilization: Despite the use of various techniques to enhance the light absorption capacity of the solar cell, due to material and structural limitations, the light utilization rate is still not high, especially in the absorption of ultraviolet light and part of the short-wavelength light.

[0006] In Chinese Patent (Publication No. CN111564532B), a HAC solar cell post-processing efficiency enhancement equipment is disclosed. The equipment is a tunnel-type furnace body, with a metal chain belt as the transmission device for the solar cell pieces inside the furnace body. The furnace body is divided into a preheating section, a light-heat treatment section, and a cooling section along the direction of the solar cell pieces. The light source is placed above the light-heat treatment section in the tunnel. The solar cell pieces are moved from the inlet to the outlet by the metal chain belt. The above-mentioned patent is a efficiency enhancement technology for HJT (or HAC), which uses light injection to improve efficiency after printing. It is not suitable for crystalline silicon solar cells, and the improvement effect is limited. SUMMARY

[0007] The purpose of the present application is to solve the above-mentioned problems, and the present application provides a novel method for improving the performance of crystalline silicon solar cells using UV light.

[0008] The present application specifically adopts the following technical solutions to achieve the above-mentioned purpose. A novel method for improving the performance of crystalline silicon solar cells using UV light, comprising the following steps: S1, taking a finished product battery, retaining its current-voltage data; S2, placing it in a UV light source device, using a light source to irradiate the front of the finished product solar cell, the distance from the light source to the finished product cell is 0.01-500mm, the power of the light source is 0.01-50kW / ㎡, and the duration is 0.01-20s; S3, performing current-voltage test again, and comparing with the data before UV irradiation.

[0009] Further, the back of the finished product battery can also be treated in the same way as the front.

[0010] Further, the light source of the UV light source device adopts halogen light, LED or laser.

[0011] Further, the light source of the UV light source device adopts LED area array light source.

[0012] Further, the light source of the UV light source device adopts linear array laser.

[0013] Further, the finished product battery adopts TOPCon battery, and its process flow is: S1, alkali texturing process: under an alkali solution, a micron-level pyramid textured surface is prepared on the surface of the silicon wafer by utilizing the anisotropic characteristics of the etching rate of the silicon surface; S2, front doping diffusion process: a nanometer-level P-type layer is formed on the surface of the N-type silicon wafer by using high-temperature boron diffusion above 1000℃, which is also used to form a PN junction; S3, back boron-silicon glass removal, back alkali polishing and front boron-silicon glass removal process: first, the byproduct boron-silicon glass deposited on the back in the second diffusion process is removed, and then the back of the silicon wafer is polished to increase the reflectivity of the back and remove the damage layer on the back of the silicon wafer by the isotropic mechanism of the silicon wafer in the alkali solution environment; S4, preparation of back tunneling oxide layer and polycrystalline silicon passivation layer: first, a 1-2nm tunneling oxide layer is prepared on the back of the silicon wafer, and then a passivation film layer coexisting with doped amorphous silicon and polycrystalline silicon is deposited in situ or intrinsically by plasma-enhanced chemical vapor deposition or low-pressure chemical vapor deposition; S5, high-temperature annealing or high-temperature doping: doping phosphorus atoms at high temperature to provide high-concentration electrons to improve the passivation contact performance, reduce the proportion of amorphous silicon in the film layer, realize the preparation of polycrystalline silicon film layer, and complete the preparation of TOPCon core structure; S6. Front barrier layer removal process: Remove the front barrier layer prepared in the previous process to facilitate subsequent removal of the polysilicon layer on the front side due to the wrap-around deposition. If the barrier layer is not completely removed, the remaining film layer will act as a recombination center, greatly reducing the photoelectric conversion efficiency. S7. Cleaning process of the front polysilicon layer: The front polysilicon layer is removed by the RCA standard cleaning process. S8. Preparation of front-side aluminum oxide and silicon nitride: A 3-10 nm aluminum oxide film is deposited on the front surface of the TOPCon cell, and then a silicon nitride film is deposited on the aluminum oxide film. S9. Backside silicon nitride deposition: Silicon nitride is used to effectively passivate the backside of the silicon wafer, improving the final conversion efficiency; S10. Complete the metallization process: By printing and drying the back electrode, printing and drying the back grid line, printing and drying the front electrode, and printing and sintering the front grid line, positive and negative electrodes are formed on the front and back sides of the silicon wafer, which facilitates the collection of electrons and holes and realizes efficient current transmission. In order to further improve efficiency, TOPCon will also use electrical injection or light injection processes to excite the cell with current or strong light, change the chemical valence state of hydrogen atoms, reduce bulk defects in the silicon substrate, and improve the overall conversion efficiency.

[0014] Furthermore, the UV light source device consists of an integrated area 1 and a light source area 2. When two sets of integrated area 1 and light source area 2 are provided, the finished battery is placed between the two sets of light source areas 2.

[0015] The beneficial effects of this invention are as follows: 1. This invention improves the efficiency of crystalline silicon solar cells by approximately 0.07% through UV irradiation. This improvement directly increases the power generation capacity of the solar cells, meaning that under the same light conditions, the cells can generate more electrical energy.

[0016] 2. The UV irradiation of the present invention increases the open circuit voltage (Voc) of the battery. An increase in Voc usually means an increase in the voltage of the battery under no-load conditions, which helps to improve the overall performance of the battery.

[0017] 3. The increased fill factor of this invention will enhance the power output of the battery, thereby optimizing the battery's efficiency in actual use.

[0018] In summary, this method of improving the performance of crystalline silicon solar cells through UV light irradiation has a significant effect on efficiency improvement, especially in terms of open-circuit voltage, fill factor and overall efficiency. It can optimize the performance of the cells in multiple aspects and is expected to enhance the market competitiveness of solar cells. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the UV light source device of the present invention; Figure 2 is a schematic diagram of a finished battery structure of the present application; Figure 3 is a schematic diagram of a finished battery production process of the present application; Figure 4 is a schematic diagram of 5s light intensity of the present application; Figure 5 is a table of efficiency difference before and after UV irradiation of the present application; Figure 6 is a table of Voc difference before and after UV irradiation of the present application; Figure 7 is a table of FF difference before and after UV irradiation of the present application; Figure 8 is a table of Jsc difference before and after UV irradiation of the present application.

[0020] Reference signs: 1, integrated area; 2, light source area. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0022] Embodiment one, as shown in a new method for improving the performance of crystalline silicon solar cells using UV light, comprising the following steps: Figures 1-2 S1, take the finished battery, keep its current voltage data; S2, place it in a UV light source device, use the light source to irradiate the front of the finished solar cell, the distance from the light source to the finished solar cell is 0.01-500mm, the power of the light source is 0.01-50kW / ㎡, and the duration is 0.01-20s; S3, perform current-voltage test again, and compare with the data before UV irradiation. In addition to TOPCon cells, the present application can also be applied to HJT cells, BC cells and other new solar cell technologies.

[0023] Distance setting: from the light source to the front of the solar cell, the scattering of the light source and the consumption of the distance will be different, so we change the flux of the irradiation light reaching the surface of the cell by distance setting, and control the distance according to different production to obtain the best input and output.

[0024] Embodiment two, based on the above embodiment, also includes that the back of the finished battery can also be treated in the same way as the front.

[0025]

[0026] ​Example 3, based on the above examples, further includes a UV light source device using halogen light, LED, or laser.

[0027] Furthermore, the UV light source device uses a linear laser array.

[0028] Example 4, as Figure 2 , Figure 3 As shown, based on the above embodiments, the finished battery also uses TOPCon batteries, and its process flow is as follows: S1. Alkaline texturing process: Under alkaline solution, taking advantage of the anisotropic corrosion rate of silicon surface, a micron-level pyramidal textured surface is prepared on the silicon wafer surface; S2, Front-side doping diffusion process: High-temperature boron diffusion at temperatures above 1000℃ is used to form a nanoscale P-type layer on the surface of the N-type silicon wafer, which is also used to form a PN junction; S3, Back borosilicate glass removal, back alkaline polishing and front borosilicate glass removal process: First, remove the borosilicate glass by-product deposited on the back side in the second diffusion process. Second, through the isotropic mechanism of silicon wafers in alkaline environment, polish the back side of the silicon wafer to increase the reflectivity of the back side and remove the damaged layer on the back side of the silicon wafer. S4. Preparation of back tunneling oxide layer and polycrystalline silicon passivation layer: First, a 1-2 nm tunneling oxide layer is prepared on the back of the silicon wafer. Then, a passivation film layer with doped amorphous silicon and polycrystalline silicon coexisting is deposited in situ or intrinsically by plasma-enhanced chemical vapor deposition or low-pressure chemical vapor deposition. S5. High-temperature annealing or high-temperature doping: Doping phosphorus atoms at high temperature provides a high concentration of electrons to improve passivation contact performance, reduces the proportion of amorphous silicon in the film layer, realizes the preparation of polycrystalline silicon film layer, and completes the preparation of TOPCon core structure. S6. Front blocking layer removal process: Remove the front blocking layer prepared in the previous process to facilitate the subsequent removal of the polysilicon layer on the front side due to the wrap-around deposition. If the blocking layer is not completely removed, the remaining film layer will act as a recombination center, greatly reducing the photoelectric conversion efficiency. S7. Cleaning process of the front polysilicon layer: The front polysilicon layer is removed by the RCA standard cleaning process. S8. Preparation of front-side aluminum oxide and silicon nitride: A 3-10 nm aluminum oxide film is deposited on the front surface of the TOPCon cell, and then a silicon nitride film is deposited on the aluminum oxide film. S9. Backside silicon nitride deposition: Silicon nitride is used to effectively passivate the backside of the silicon wafer, improving the final conversion efficiency; S10. Complete the metallization process: By printing and drying the back electrode, printing and drying the back grid line, printing and drying the front electrode, and printing and sintering the front grid line, positive and negative electrodes are formed on the front and back sides of the silicon wafer, which facilitates the collection of electrons and holes and realizes efficient current transmission. In order to further improve efficiency, TOPCon will also use electrical injection or light injection processes to excite the cell with current or strong light, change the chemical valence state of hydrogen atoms, reduce bulk defects in the silicon substrate, and improve the overall conversion efficiency.

[0029] Example 5, such as Figure 1 As shown, based on the above embodiment, the UV light source device is further composed of an integrated area 1 and a light source area 2. When two sets of integrated area 1 and light source area 2 are provided, the finished battery is placed between the two sets of light source areas 2. The integrated area 1 and light source area 2 below can be selectively set.

[0030] Example 6, as Figures 4-8 As shown, a novel method for improving the performance of crystalline silicon solar cells using UV light includes the following steps: S1. Take ten sets of finished batteries and retain their current and voltage data; S2. Place it in a UV light source device. The light source is an LED array light source with a wavelength of 356nm. Use the light source to irradiate the front of the finished solar cell. The distance from the light source to the finished cell is 10mm. The power of the light source is 1kW / ㎡. The duration is 1s-10s for each of the ten finished cells. S3. Perform the current and voltage test again and compare it with the data before UV irradiation.

[0031] Comparison table of data before and after UV irradiation; Depend on Figure 4 It can be seen that under the experimental light intensity conditions, when the irradiation time is 6s and 7s, the cell efficiency is significantly improved by approximately 0.07%. When the irradiation time is 9s, the cell efficiency is improved by approximately 0.05%. Depend on Figure 5 It can be seen that under the experimental light intensity conditions, the Voc of the solar cell irradiated for different times is increased to a certain extent. When the irradiation time is 3-7s and 9s, the Voc increase is greater than 1mV. Depend on Figure 6 It can be seen that under the experimental light intensity conditions, when the irradiation time is 6s and 7s, the FF increases significantly, by about 0.1% and 0.08% respectively. When the irradiation time is 9s, the FF increases by about 0.02%. At other times, the FF decreases to varying degrees. The trend of FF before and after UV irradiation is similar to that of efficiency. It can be preliminarily concluded that the efficiency improvement of TOPCon battery after UV irradiation is due to the improvement of FF (fill factor). In summary, under certain conditions, the finished battery piece is irradiated by UV light, which can effectively improve the photoelectric conversion efficiency of the TOPCon battery.

[0032] It should be noted that, compared with the technology mentioned in the background art, the present application is to use a special UV wavelength for further efficiency improvement after the HJT light injection process, or after the TOPCon light injection and laser assisted sintering process. The present application can not only be used in low temperature processes such as HJT and HBC, but also can be used in high temperature processes such as PERC and TOPCon.

[0033] The above description of disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A novel method for improving the performance of crystalline silicon solar cells using UV light, characterized in that, Includes the following steps: S1. Take the finished battery and retain its current and voltage data; S2. Place it in a UV light source device and use the light source to irradiate the front of the finished solar cell. The distance from the light source to the finished solar cell is 0.01-500mm, the power of the light source is 0.01-50kW / ㎡, and the duration is 0.01-20s. S3. Perform the current and voltage test again and compare it with the data before UV irradiation.

2. The novel method for improving the performance of crystalline silicon solar cells using UV light according to claim 1, characterized in that, The back of the finished battery can also be treated in the same way as the front.

3. The novel method for improving the performance of crystalline silicon solar cells using UV light according to claim 1, characterized in that, The UV light source device uses halogen light, LED or laser.

4. A novel method for improving the performance of crystalline silicon solar cells using UV light according to claim 3, characterized in that, The UV light source device uses an LED array light source.

5. A novel method for improving the performance of crystalline silicon solar cells using UV light according to claim 3, characterized in that, The UV light source device uses a linear laser array.

6. A novel method for improving the performance of crystalline silicon solar cells using UV light according to claim 1, characterized in that, The finished battery uses TOPCon batteries, and its process flow is as follows: S1. Alkaline texturing process: Under alkaline solution, taking advantage of the anisotropic corrosion rate of silicon surface, a micron-level pyramidal textured surface is prepared on the silicon wafer surface; S2, Front-side doping diffusion process: High-temperature boron diffusion at temperatures above 1000℃ is used to form a nanoscale P-type layer on the surface of the N-type silicon wafer, which is also used to form a PN junction; S3, Back borosilicate glass removal, back alkaline polishing and front borosilicate glass removal process: First, remove the borosilicate glass by-product deposited on the back side in the second diffusion process. Second, through the isotropic mechanism of silicon wafers in alkaline environment, polish the back side of the silicon wafer to increase the reflectivity of the back side and remove the damaged layer on the back side of the silicon wafer. S4. Preparation of back tunneling oxide layer and polycrystalline silicon passivation layer: First, a 1-2 nm tunneling oxide layer is prepared on the back of the silicon wafer. Then, a passivation film layer with doped amorphous silicon and polycrystalline silicon coexisting is deposited in situ or intrinsically by plasma-enhanced chemical vapor deposition or low-pressure chemical vapor deposition. S5. High-temperature annealing or high-temperature doping: Doping phosphorus atoms at high temperature provides a high concentration of electrons to improve passivation contact performance, reduces the proportion of amorphous silicon in the film layer, realizes the preparation of polycrystalline silicon film layer, and completes the preparation of TOPCon core structure. S6. Front blocking layer removal process: Remove the front blocking layer prepared in the previous process to facilitate the subsequent removal of the polysilicon layer on the front side due to the wrap-around deposition. If the blocking layer is not completely removed, the remaining film layer will act as a recombination center, greatly reducing the photoelectric conversion efficiency. S7. Cleaning process of the front polysilicon layer: The front polysilicon layer is removed by the RCA standard cleaning process. S8. Preparation of front-side aluminum oxide and silicon nitride: A 3-10 nm aluminum oxide film is deposited on the front surface of the TOPCon cell, and then a silicon nitride film is deposited on the aluminum oxide film. S9. Backside silicon nitride deposition: Silicon nitride is used to effectively passivate the backside of the silicon wafer, improving the final conversion efficiency; S10. Complete the metallization process: By printing and drying the back electrode, printing and drying the back grid line, printing and drying the front electrode, and printing and sintering the front grid line, positive and negative electrodes are formed on the front and back sides of the silicon wafer, which facilitates the collection of electrons and holes and realizes efficient current transmission. In order to further improve efficiency, TOPCon will also use electrical injection or light injection processes to excite the cell with current or strong light, change the chemical valence state of hydrogen atoms, reduce bulk defects in the silicon substrate, and improve the overall conversion efficiency.

7. A novel method for improving the performance of crystalline silicon solar cells using UV light according to claim 2, characterized in that, The UV light source device consists of an integrated area (1) and a light source area (2). When two sets of integrated area (1) and light source area (2) are set, the finished battery is placed between the two sets of light source areas (2).

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