A kind of front silver paste of solar cell and preparation method thereof

Abstract

The invention discloses silver paste for the front surface of a solar battery. The silver paste comprises the following components in percentage by weight: 78 to 90 percent of silver powder, 1 to 5 percent of glass powder, 7 to 15 percent of organic bonding agent and 0 to 3 percent of auxiliary agent, wherein the glass powder comprises SiO2, Al2O3, Bi2O3, ZnO, B2O3 and TeO2; the organic bonding agent comprises an organic carrier and an organic solvent. The invention also discloses a method for preparing the silver paste. The method comprises the following steps: weighing each component of the glass powder; performing heating and ball milling on each component to obtain the glass powder with the particle size of less than 5 mu m; mixing, heating, stirring and dissolving the organic bonding agent; adding the silver powder, the glass powder and the auxiliary agent into the organic bonding agent; rolling and grinding the mixture through a three-roller rolling machine until the particle size is less than 5 mu m and the viscosity is 290 to 380 Pa.S to obtain the paste. The silver paste produced by the method is good in printing effect, stable in performance and high in conversion rate; the depth-width ratio of a grid line is large after the silver paste is sintered.

Description

technical field [0001] The invention belongs to the technical field of paste for solar cells, in particular to a front silver paste for solar cells and a preparation method thereof. Background technique [0002] With the increasingly serious environmental pollution and the deepening of the concept of low-carbon environmental protection, safe, clean and efficient energy is more and more popular among people. Among them, crystalline silicon solar cell technology, as the mainstream of solar technology development, has been receiving much attention. Through continuous research on solar cell technology, the conversion efficiency of cells has been continuously improved. [0003] A solar cell is a device that converts light energy into electrical energy through the photoelectric effect. The working principle of photoelectric effect solar cells: when sunlight irradiates on the p-n junction of crystalline silicon semiconductor, new hole-electron pairs are formed, and under the actio...

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Problems solved by technology

[0005] The silver paste for the front electrode is usually composed of silver powder, glass powder and organic carrier, among which the silver powder is the conductive medium, and the glass powder melts during high-temperature sintering to form an ohmic contact between the silver powder and the semiconductor silicon substrate; the organic carrier acts as the silver powder The role of particle dispersion and encapsulation makes the silver powder in the conductive silver paste not easy to precipitate and oxidize; in order to improve the printing effect, a certain amount of additives are usually added to the paste to improve the anti-settling and anti-sag properties of the paste. Increase the fluidity of the silver paste, and maintain a moderately stable fluidity to ensure the quality of screen printing. After standing still, the fluidity decreases and the viscosity increases. The thin lines of the silk screen can maintain their shape, and then obtain an ideal aspect ratio. Thereby improve each performance index of paste; Yet, this thixotropy and stability of the positive silver paste in the prior art still need to be improved; In addition, the used glass frit of the solar cell conductive silver paste in the prior art is usually Lead-containing mixed powder. Although the glass powder has a low softening temperature and good electrical stability, it contains high lead content, which seriously pollutes the environment and does not meet environmental protection requirements.

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