HJT solar cell based on metal grid copper electrode

Abstract

The invention discloses an HJT solar cell based on a metal grid copper electrode, which comprises an N-type monocrystalline silicon substrate, the front surface and the back surface of the N-type monocrystalline silicon substrate are respectively textured, an I-type amorphous silicon layer and a P-type amorphous silicon layer are sequentially laminated on the front surface of the N-type monocrystalline silicon substrate, and an I-type amorphous silicon layer and an N-type amorphous silicon layer are sequentially laminated on the back surface of the N-type monocrystalline silicon substrate; the surface of the P-type amorphous silicon layer and the surface of the N-type amorphous silicon layer are both covered with transparent conductive oxide layers, the transparent conductive oxide layers are coated with transparent conductive colloid layers, the transparent conductive colloid layers comprise transparent resin binders and conductive substances dispersed in the transparent resin binders, and metal grid copper electrodes are arranged on the transparent conductive colloid layers; through precise design of the line width and the spacing of the metal grid copper electrode, the shading rate can be reduced to the maximum extent while low square resistance and efficient current collection can be ensured, and the requirements of scenes such as building integrated photovoltaic and the like for high-light-transmittance and low-resistance electrodes are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a HJT solar cell based on a metal mesh copper electrode. BACKGROUND

[0002] As a core device of clean energy conversion, the technical development of solar cells is of great significance to energy transformation. Heterojunction (HJT) solar cells have become an important development direction of high-efficiency photovoltaic technology due to their high open-circuit voltage, low temperature coefficient, and double-sided power generation capability. However, existing HJT cells face multiple technical bottlenecks in electrode structure design:

[0003] Commercial HJT cells generally use screen-printed silver paste electrodes. Silver, as a rare noble metal, has a high raw material cost, accounting for a high proportion of the total cost of the cell, and its price fluctuates dramatically, which seriously hinders the market competitiveness of HJT cells. Building-integrated photovoltaics and other scenarios require electrodes with high light transmittance and low sheet resistance. Traditional silver grid electrodes need to increase the line width to meet the electrical conductivity, resulting in a significant decrease in light transmittance. If the line width is reduced, the resistance will increase dramatically, making it difficult to optimize both simultaneously. Wearable devices and flexible components require electrodes to withstand repeated bending and deformation, but silver paste electrodes form brittle metal crystal structures after high-temperature sintering. In a humid and hot environment, traditional silver electrodes and TCO interfaces are prone to electrochemical corrosion, resulting in power attenuation after aging. In addition, ultraviolet radiation causes the organic binder to yellow, further reducing light utilization. SUMMARY

[0004] The present application aims to provide a HJT solar cell based on a metal mesh copper electrode to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a HJT solar cell based on a metal mesh copper electrode, the solar cell comprising an N-type monocrystalline silicon substrate, and the front and back surfaces are respectively subjected to texturing treatment;

[0006] The front surface of the N-type monocrystalline silicon substrate is sequentially stacked with an I-type amorphous silicon layer and a P-type amorphous silicon layer, and the back surface of the N-type monocrystalline silicon substrate is sequentially stacked with an I-type amorphous silicon layer and an N-type amorphous silicon layer.

[0007] The surfaces of the P-type amorphous silicon layer and the N-type amorphous silicon layer are covered with a transparent conductive oxide layer, the transparent conductive oxide layer is coated with a transparent conductive colloid layer, the transparent conductive colloid layer comprises a transparent resin binder and a conductive substance dispersed therein, and the transparent conductive colloid layer is provided with a metal mesh copper electrode.

[0008] Preferably, the line width of the metal mesh copper electrode is 5-50 μm, the pitch is 0.5-5 mm, and the thickness is 5-50 μm.

[0009] Preferably, the conductive substance in the transparent conductive colloidal layer comprises Cu / Ag alloy particles with a particle size of 1-10 microns, carbon nanotubes with an aspect ratio greater than 1000, and 3,4-ethylenedioxythiophene conductive polymer.

[0010] Preferably, the metal mesh copper electrode is prepared by a transfer method, comprising the following steps:

[0011] S1: forming a copper mesh on a flexible transparent polymer substrate by yellow light etching;

[0012] S2: turning over and pressing the substrate with the copper mesh on the surface of the transparent conductive oxide coated with a transparent conductive colloidal layer;

[0013] S3: peeling off the polymer substrate after curing at 80-100°C for 30 minutes.

[0014] Preferably, the metal mesh copper electrode is prepared by a direct writing method, comprising the following steps:

[0015] S11: coating a transparent conductive colloidal layer on the surface of the transparent conductive oxide layer;

[0016] S12: arranging copper wires on the surface of the colloidal layer according to the design pattern by using a metal wire direct writing technology;

[0017] S13: completing electrode formation by curing at 80-100°C for 30 minutes.

[0018] Preferably, the curing process is carried out under inert gas protection, and the temperature rising rate is controlled at 2-5°C / min.

[0019] Preferably, a composite protective layer is further encapsulated on the surface of the battery, and the composite protective layer comprises, from inside to outside, a UV cured adhesive layer, a fluororesin film layer, and an anti-fouling coating layer.

[0020] Preferably, a titanium oxide electron transport layer is arranged between the N-type amorphous silicon layer and the transparent conductive oxide layer, and the thickness of the titanium oxide electron transport layer is 2-5 nm.

[0021] Preferably, 0.1-1wt% of silica nanospheres are doped in the transparent conductive colloidal layer, and the surface of the nanospheres is coated with silver nanoparticles.

[0022] Preferably, the flexible transparent polymer substrate is made of polyimide, polyethylene terephthalate, or polyvinyl naphthalene.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] 1. The present application can meet the demand for high light transmittance and low resistance electrode in building integrated photovoltaic and other scenarios by precisely designing the line width and pitch of the metal mesh copper electrode, while ensuring low sheet resistance and efficient current collection.

[0025] 2. The present application effectively prevents copper oxidation and colloid layer degradation through low-temperature curing process under inert gas protection, further isolates water and oxygen, resists ultraviolet aging and chemical corrosion, realizes self-cleaning, significantly reduces electrochemical corrosion and yellowing problem caused by ultraviolet radiation in humid environment, prolongs the service life of the battery, and reduces power attenuation.

[0026] 3. The present application ensures efficient conduction through the synergistic effect of multiple conductive substances in the transparent conductive colloid layer, the silver nanoparticles enhanced by silica nanosphere core not only improve local conductivity, but also enhance light capture through scattering effect, the ultra-thin design of titanium oxide electron transport layer effectively inhibits hole reverse transmission, reduces interface recombination, enhances electron tunneling, and further improves the open circuit voltage and fill factor of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 The structure diagram of the HJT solar cell based on the metal mesh copper electrode of the present application.

[0028] Fig. 2 The structure diagram of the composite protective layer of the present application.

[0029] Fig. 3 The flowchart of the metal mesh transfer method of the present application.

[0030] Fig. 4 The flowchart of the metal mesh direct writing method of the present application.

[0031] In the figure: N-type monocrystalline silicon substrate 1; I-type amorphous silicon layer 2; P-type amorphous silicon layer 3; N-type amorphous silicon layer 4; transparent conductive oxide layer 5; metal mesh copper electrode 6; transparent conductive colloid layer 7; titanium oxide electron transport layer 8; composite protective layer 9. DETAILED DESCRIPTION

[0032] The technical solutions 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. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0033] Please refer to Figs. 1 to 4The present invention provides a technical solution: an HJT solar cell based on a metal grid copper electrode, the solar cell includes an N-type single crystal silicon substrate 1, and the front and back sides are respectively textured to increase the light absorption area and remove surface impurities.

[0034] The front side of the N-type single crystal silicon substrate 1 is sequentially stacked with an I-type amorphous silicon layer 2 and a P-type amorphous silicon layer 3, and the back side of the N-type single crystal silicon substrate 1 is sequentially stacked with an I-type amorphous silicon layer 2 and an N-type amorphous silicon layer 4.

[0035] The I-layer amorphous silicon 2 can effectively passivate substrate surface defects and reduce carrier recombination. The P-type amorphous silicon layer 3 forms a pn heterojunction with the N-type single crystal silicon substrate 1 to achieve the separation of photogenerated carriers. A back surface field is formed on the back side of the N-type single crystal silicon substrate 1, which helps to improve the open circuit voltage and fill factor of the battery.

[0036] The surfaces of the P-type amorphous silicon layer 3 and the N-type amorphous silicon layer 4 are both covered with a transparent conductive oxide layer 5. The transparent conductive oxide layer 5 not only reduces the series resistance when collecting current and improves the carrier transmission efficiency, but also has an anti-reflection effect similar to the silicon nitride layer on the crystalline silicon cell, which can effectively reduce the reflection of light on the cell surface, increase the amount of light absorbed, and thus improve the photoelectric conversion efficiency of the cell.

[0037] A transparent conductive colloid layer 7 is coated on the transparent conductive oxide layer 5. The transparent conductive colloid layer 7 includes a transparent resin binder and a conductive substance dispersed therein. A metal grid copper electrode 6 is provided on the transparent conductive colloid layer 7. These conductive substances can enhance the conductivity of the colloid and ensure efficient transmission of carriers between the electrode and the transparent conductive oxide layer 5. At the same time, the transparent resin binder ensures the transparency of the colloid and reduces the impact on light absorption.

[0038] The line width of the metal grid copper electrode 6 is 5-50μm, balancing the shading rate and current collection capability, with a spacing of 0.5-5mm, matching the square resistance of the transparent conductive oxide layer 5, optimizing the carrier transmission path, and a thickness of 5-50μm, ensuring low resistance while avoiding stress cracking.

[0039] The conductive material in the transparent conductive colloid layer 7 includes Cu / Ag alloy particles with a particle size of 1-10 μm, carbon nanotubes with an aspect ratio greater than 1000, and 3,4-ethylenedioxythiophene conductive polymer. 0.1-1 wt% of silica nanospheres are doped into the transparent conductive colloid layer 7. The surface of the nanospheres is coated with silver nanoparticles. The silver nanoparticles enhance local conductivity, and the silica nanosphere cores scatter light to enhance light capture.

[0040] The metal grid copper electrode 6 is prepared by a transfer method, comprising the following steps:

[0041] S1: A copper grid is formed on a flexible transparent polymer substrate using yellow light etching. The flexible transparent polymer substrate is made of one of polyimide, polyethylene terephthalate, and polyethylene naphthalate, which is resistant to high temperatures and has a thermal expansion coefficient that matches that of the silicon wafer to avoid peeling and deformation.

[0042] S2: turning over and pressing the substrate with the copper grid onto the transparent conductive oxide surface coated with the transparent conductive colloid layer 7;

[0043] S3: After curing at 80-100°C for 30 minutes, the polymer substrate is peeled off to activate the cross-linking reaction of the colloidal layer and form a stable electrode-colloid interface.

[0044] The metal grid copper electrode 6 is prepared by a direct writing method, comprising the following steps:

[0045] S11: coating a transparent conductive colloid layer 7 on the surface of the transparent conductive oxide layer 5;

[0046] S12: Copper wires are arranged on the surface of the colloidal layer according to the designed pattern using metal wire direct writing technology. Copper wire direct writing is maskless patterning and adapts to customized electrode design.

[0047] S13: Curing at 80-100°C for 30 minutes to complete electrode formation. Low temperature curing avoids rapid evaporation of the colloidal layer solvent, which may cause pores or cracks.

[0048] Both the transfer method and the direct writing method adopt the curing process to be carried out under the protection of inert gas, and the heating rate is controlled at 2-5°C / min. The inert gas protection prevents copper oxidation and degradation of the colloidal layer.

[0049] It also includes a composite protective layer 9 encapsulated on the surface of the battery. The composite protective layer 9 consists of a UV-curing adhesive layer, a fluororesin film layer and an anti-fouling coating from the inside to the outside. The UV-curing adhesive layer is quickly formed and bonds to subsequent layers to isolate water and oxygen; the fluororesin film layer is resistant to UV aging and chemical corrosion and maintains light transmittance; the anti-fouling coating is hydrophobic and self-cleaning, reducing efficiency loss caused by dust deposition.

[0050] A titanium oxide electron transport layer 8 is provided between the N-type amorphous silicon layer 4 and the transparent conductive oxide layer 5. The thickness of the titanium oxide electron transport layer 8 is 2-5 nm. The ultra-thin layer of the titanium oxide electron transport layer 8 inhibits the reverse transport of holes, reduces interface recombination, and enhances the electron tunneling effect.

[0051] After light penetrates the composite protective layer 9 and the transparent conductive colloid layer 7, it enters the interior of the battery through the anti-reflection effect of the TCO layer 5; the double-sided texturing structure of the N-type single-crystalline silicon substrate 1 enhances light capture, and photons are absorbed to generate electron-hole pairs; photogenerated holes are collected by the P-type amorphous silicon layer 3 and laterally transmitted to the metal grid copper electrode 6 through the TCO layer 5. The I-type amorphous silicon layer 2 passivates interface defects and suppresses carrier recombination; photogenerated electrons form a back surface field through the N-type amorphous silicon layer 4, accelerating their transmission to the electrode; the 2-5nm ultra-thin layer of the titanium oxide electron transport layer 8 selectively blocks the reverse transmission of holes, reduces interface recombination, and the quantum tunneling effect improves the electron extraction efficiency.

[0052] The carriers pass through the multi-level conductive network of the transparent conductive colloid layer 7, the Cu / Ag alloy particles construct the basic conductive path; the carbon nanotubes form a through-type conductive bridge to reduce the contact resistance; and the PEDOT polymer fills the gaps to improve the interface adhesion.

[0053] The present invention replaces traditional silver paste electrodes with metal grid copper electrodes, significantly reducing material costs and improving product market competitiveness, which is conducive to the large-scale promotion and application of HJT solar cells; the high conductivity of the metal grid copper electrode reduces the resistance loss of the battery, and the synergistic effect of the transparent conductive oxide layer 5 and the metal grid copper electrode 6 increases the light absorption and carrier transmission efficiency, thereby improving the photoelectric conversion efficiency of the battery; the flexibility of the metal grid copper electrode 6 enables solar cells to be applied to more special scenarios, such as wearable devices, flexible solar panels, etc., broadening the application field of solar cells; the composite protective layer 9 effectively protects the internal structure of the battery, improves the stability and service life of the battery under different environmental conditions, and reduces maintenance costs.

[0054] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A HJT solar cell based on a metal grid copper electrode, characterized by: The solar cell comprises an N-type single crystal silicon substrate (1), and the front and back surfaces are respectively textured; An I-type amorphous silicon layer (2) and a P-type amorphous silicon layer (3) are sequentially stacked on the front side of an N-type single crystal silicon substrate (1), and an I-type amorphous silicon layer (2) and an N-type amorphous silicon layer (4) are sequentially stacked on the back side of the N-type single crystal silicon substrate (1); The surfaces of the P-type amorphous silicon layer (3) and the N-type amorphous silicon layer (4) are both covered with a transparent conductive oxide layer (5), a transparent conductive colloid layer (7) is coated on the transparent conductive oxide layer (5), the transparent conductive colloid layer (7) comprises a transparent resin binder and a conductive substance dispersed therein, and a metal grid copper electrode (6) is provided on the transparent conductive colloid layer (7).

2. The HJT solar cell based on a metal grid copper electrode according to claim 1, characterized in that: The metal grid copper electrode (6) has a line width of 5-50 μm, a spacing of 0.5-5 mm, and a thickness of 5-50 μm.

3. The HJT solar cell based on a metal grid copper electrode according to claim 1, characterized in that: The conductive material in the transparent conductive colloid layer (7) includes Cu / Ag alloy particles with a particle size of 1-10 μm, carbon nanotubes with an aspect ratio greater than 1000, and 3,4-ethylenedioxythiophene conductive polymer.

4. The HJT solar cell based on a metal grid copper electrode according to claim 1, characterized in that: The metal grid copper electrode (6) is prepared by a transfer method, comprising the following steps: S1: Copper grid formed on a flexible transparent polymer substrate using yellow light etching; S2: turning over the substrate with the copper grid and pressing it onto the transparent conductive oxide surface coated with the transparent conductive colloid layer (7); S3: Peel off the polymer substrate after curing at 80-100°C for 30 minutes.

5. The HJT solar cell based on a metal grid copper electrode according to claim 1, characterized in that: The metal grid copper electrode (6) is prepared by a direct writing method, comprising the following steps: S11: coating a transparent conductive colloid layer (7) on the surface of the transparent conductive oxide layer (5); S12: Using metal wire direct writing technology to arrange copper wires on the surface of the colloidal layer according to the designed pattern; S13: Curing at 80-100° C. for 30 minutes to complete electrode formation.

6. The HJT solar cell based on a metal grid copper electrode according to claim 4, characterized in that: The curing process is carried out under the protection of inert gas, and the heating rate is controlled at 2-5°C / min.

7. The HJT solar cell based on a metal grid copper electrode according to claim 1, characterized in that: It also includes a composite protective layer (9) encapsulated on the surface of the battery, and the composite protective layer (9) comprises a UV curing adhesive layer, a fluororesin film layer and an antifouling coating layer from the inside to the outside.

8. The HJT solar cell based on a metal grid copper electrode according to claim 1, characterized in that: A titanium oxide electron transport layer (8) is provided between the N-type amorphous silicon layer (4) and the transparent conductive oxide layer (5), and the thickness of the titanium oxide electron transport layer (8) is 2-5 nm.

9. The HJT solar cell based on a metal grid copper electrode according to claim 3, characterized in that: 0.1-1 wt% of silicon dioxide nanospheres are doped into the transparent conductive colloid layer (7), and the surfaces of the nanospheres are coated with silver nanoparticles.

10. The HJT solar cell based on metal grid copper electrode according to claim 4, characterized in that: The substrate of the flexible transparent polymer is made of polyimide, polyethylene terephthalate, and polyethylene naphthalate.

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