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CN-122000113-A - Graphene-copper composite conductive paste and application thereof in high-efficiency photovoltaic cells

CN122000113ACN 122000113 ACN122000113 ACN 122000113ACN-122000113-A

Abstract

The invention discloses graphene-copper composite conductive paste and a preparation method and application thereof. The slurry comprises graphene coated copper composite powder, a low-melting-point alloy bonding agent, functional glass powder and an organic carrier. The graphene-coated copper composite powder is prepared by in-situ growth of a few layers of graphene on the surface of copper powder by a chemical vapor deposition method, and a core-shell enhanced conductive unit is formed. According to the invention, the complete replacement of silver by copper in the photovoltaic electrode material (silver content is less than 1%) is realized for the first time, meanwhile, the performance damage of a pure copper system is made up by the enhancement effect of graphene, and the photoelectric conversion efficiency reaches more than 97% of commercial silver paste on the basis that the material cost is reduced to 1/60 of that of the silver paste. The slurry is suitable for the preparation of electrodes of various high-efficiency photovoltaic cells such as HJT, TOPCon, perovskite and the like, and has remarkable economic benefit and strategic significance.

Inventors

  • LIU HEPING

Assignees

  • 刘和平

Dates

Publication Date
20260508
Application Date
20260319

Claims (9)

  1. 1. The graphene-copper composite conductive paste is characterized by comprising, by mass, 80-90% of graphene-coated copper composite powder, 2-6% of a low-melting-point alloy bonding agent, 1-4% of functional glass powder and 7-12% of an organic carrier.
  2. 2. The graphene-copper composite conductive paste according to claim 1, wherein in the graphene-coated copper composite powder, the surface of copper powder particles is coated with 1-5 layers of few layers of graphene, and the mass of graphene accounts for 0.5-5% of the composite powder.
  3. 3. The graphene-copper composite conductive paste according to claim 1, wherein the low melting point alloy bonding agent is selected from one or more of indium-based alloy, bismuth-based alloy, or tin-based alloy.
  4. 4. The graphene-copper composite conductive paste according to claim 1, wherein the functional glass frit is a bismuth-based lead-free glass frit or a tellurite glass frit, and the softening temperature thereof is between 400 and 550 ℃.
  5. 5. The graphene-copper composite conductive paste according to claim 1, wherein the organic carrier is composed of an organic solvent, a thixotropic agent and a dispersing agent, wherein the organic solvent is selected from terpineol, butyl carbitol or a mixture thereof, the thixotropic agent is selected from one or two of ethylcellulose and hydrogenated castor oil, and the dispersing agent is selected from one or more of polyvinylpyrrolidone and phosphate esters.
  6. 6. A method for preparing the graphene-copper composite conductive paste according to any one of claims 1 to 5, comprising the steps of: preparing graphene coated copper composite powder; mixing the graphene coated copper composite powder, a low-melting-point alloy bonding agent, functional glass powder and an organic carrier in a protective atmosphere, and grinding until the fineness is less than or equal to 5 mu m to obtain mixed slurry; and (3) placing the mixed slurry in a vacuum deaerator, and removing bubbles at a vacuum degree of below-0.08 MPa to obtain the final slurry.
  7. 7. The preparation method of claim 6, wherein the graphene-coated copper composite powder is prepared by a chemical vapor deposition method, and comprises the following steps: pretreating copper powder for 30-60 minutes at 300-500 ℃ in a reducing atmosphere; placing the mixture in a CVD reaction chamber, vacuumizing, introducing protective gas, and heating to 800-1050 ℃; introducing carbon source gas and hydrogen, reacting for 10-60 minutes, and growing graphene on the surface of the copper powder in situ; cooling to room temperature under the protection atmosphere.
  8. 8. Use of the graphene-copper composite conductive paste according to any one of claims 1 to 5 for the preparation of an electrode for a photovoltaic cell.
  9. 9. The use according to claim 8, characterized in that it comprises the step of applying the paste to the surface of the silicon substrate by screen printing, after drying at 150-200 ℃, sintering at 600-850 ℃ under inert gas protection, or sintering with light pulses below 200 ℃ in low temperature batteries.

Description

Graphene-copper composite conductive paste and application thereof in high-efficiency photovoltaic cells Technical Field The invention relates to the technical field of photovoltaic materials, in particular to graphene-copper composite conductive paste for a photovoltaic cell electrode, and a preparation method and application thereof. Background Silver paste is the most critical non-silicon material in the current production of crystalline silicon photovoltaic cells and plays a core role in forming electrodes and collecting current. Currently, photovoltaic silver paste occupies 27% of the non-silicon cost of the cell, and is one of the most expensive materials in photovoltaic modules. The continuous rising of the price of silver and the increasing of the unit consumption of silver paste by the N-type battery technology make the cost reduction demand particularly urgent. The silver consumption in the photovoltaic industry is huge, and the solar photovoltaic manufacturing in 2024 accounts for 32% of the global industrial silver consumption. With the continuous increase of the global photovoltaic installation capacity, the scarcity and price fluctuation of silver resources have become bottlenecks restricting the sustainable development of the photovoltaic industry. The industry is always exploring alternatives to silver paste, and copper is the most potential alternative material because of conductivity inferior to silver and cost of only 1% of silver. However, the mere substitution of copper for silver presents a number of technical challenges, namely the tendency of copper to oxidize in air, the rapid diffusion rate in silicon, the resulting junction contamination, the ohmic contact with the silicon substrate being inferior to silver, and the narrow sintering process window. In the prior art, the silver-coated copper technology is applied but still contains about 30 percent of silver, and the electroplating copper technology has complex process and lower yield of mass production. Therefore, developing an electrode paste which can completely get rid of the dependence on silver, can maintain high-efficiency photoelectric conversion performance and is suitable for mass production becomes a technical problem which needs to be solved urgently in the photovoltaic industry. Disclosure of Invention The invention aims to provide graphene-copper composite conductive paste and a preparation method thereof, and aims to realize the double breakthrough of the radical cost reduction and the performance enhancement of a photovoltaic cell electrode material. The technical scheme is that the graphene-copper composite conductive paste comprises the following components in percentage by mass: 80-90% of graphene coated copper composite powder Wherein copper is used as a core, few layers of graphene (1-5 layers) are used as coating layers, and the mass of the graphene accounts for 0.5-5% of the composite powder. 2-6% Of low-melting-point alloy bonding agent Is selected from indium-based, bismuth-based or tin-based alloy powder, and is used for bridging the composite powder and the silicon matrix during sintering to form excellent ohmic contact. 1-4% Of functional glass powder The softening temperature is between 400 and 550 ℃, and the graphene-copper composite powder is assisted to be in etching contact with the silicon wafer. 7-12% Of organic carrier Consists of an organic solvent, a thixotropic agent and a dispersing agent. The key preparation process comprises the following steps: And preparing composite powder, namely directly growing graphene on the surface of copper powder by adopting a chemical vapor deposition method to form a compact and uniform coating layer. And (3) mixing and dispersing the slurry, namely mixing the composite powder with alloy powder, glass powder and an organic carrier in a protective atmosphere, grinding until the fineness is less than or equal to 5 mu m, and carrying out vacuum defoaming to obtain the composite powder. The most critical technical characteristics of the invention are that the graphene is accurately attached to the surface of the copper powder to form a coating structure, so that the subversion advantage complementation is realized: copper forms a macroscopic three-dimensional network with low cost and high conduction, and is a basic stone for realizing 'low-cost substitution'; the graphene exerts intrinsic ultra-high mobility, and an electronic expressway is erected among copper particles, so that the overall conductivity is remarkably improved; The combination of the two can realize the high performance of the graphene through a copper practical carrier, and the stability and cost advantages of the copper are exerted to the greatest extent due to the enhancement of the graphene. Detailed Description Example 1 Low temperature composite paste for HJT Battery The embodiment provides a graphene-copper composite conductive paste, which comprises, by mass, 85% of graphene-coated copper