A kind of back silver paste for double-sided perc solar cells

Abstract

The invention discloses a back silver paste for double-sided PERC solar cells. The composition and mass percentage of the paste are: 35-50% of a first-class spherical silver powder, 5-20% of a second-class spherical silver powder, 0.5-50% 5% glass powder, 35-50% organic binder, 4-10% thixotropic agent, 0.5-5% auxiliary agent, 0.01-2% inorganic additive, and the inorganic additive is CaSiO 3 、Al 2 (SiO 3 ) 3 , gas phase SiO 2 、Al 2 o 3 , SiNx, and in the process of preparing the slurry, the inorganic additive and the glass powder are ball-milled, mixed and coated, and then mixed with other components of the slurry to make a slurry. In the present invention, by selecting inorganic powdery additives with good affinity with silicon wafers, they can be attached to the surface of silicon wafers during sintering, have a certain barrier effect on the contact between glass powder and silicon wafers, and slow down the impact of glass powder on silicon wafers during the melting process. The erosion speed is high, and the open circuit voltage is increased; the inorganic additive is mixed with the glass powder in advance, which can realize the precise barrier of the glass powder and improve the barrier efficiency of the inorganic additive.

Description

technical field [0001] The invention relates to the technical field of conductive paste, in particular to a back silver paste for double-sided PERC solar cells. Background technique [0002] In the past two years, in the field of photovoltaics, PERC cells have gradually surpassed traditional structure cells and become mainstream products in the market. PERC (Passivated Emitter and Rear Cell) is passivated emitter and rear cell technology. Surface passivation, the back electrode adopts the form of partial contact, which effectively reduces the recombination of the back and improves the absorption of long waves, thereby improving the conversion efficiency of the cell. [0003] The silver paste on the back of the solar cell is mainly composed of silver powder, organic solvent, inorganic binder and additives. As the functional phase in the paste, the silver powder mainly plays the role of conductivity. In the production process of solar modules, the back electrode needs to be ...

AI Technical Summary

Problems solved by technology

In the production process of solar modules, the back electrode needs to be in contact with the silicon wafer. However, when the existing back silver paste erodes the back silicon wafer, the damage area to the overlapping aluminum paste layer is large, resulting in no silver paste layer. The covered part of the silicon wafer is exposed, not covered and protected by the aluminum paste layer, and the outer edge of the part of the silver paste layer in contact with the aluminum paste layer has poor compatibility, resulting in an unstable contact interface between the aluminum paste layer and the silver paste layer

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