Experimental Investigation of Effect of Flake Silver Powder Content on Sintering Structure and Properties of Front Silver Paste of Silicon Solar Cell

Abstract

Optimizing the performance of front silver paste is of great significance in improving the efficiency of the photoelectric conversion of crystalline silicon solar cells. As a conductive functional phase of silver paste, the structure and performance of silver powder have an important influence on the sintering process of silver paste and the conductivity of silver electrodes. Because of their two−dimensional structure, flake silver powders can effectively increase the contact area with other silver powders and silicon cells before sintering. Additionally, flake silver particles have higher surface energy and sintering activity than spherical silver particles of the same particle size. However, recent research has mainly focused on the influence of the particle size of silver powder. This paper fills the research gap regarding the morphology of silver powders and clarifies the influence of flake silver powders on the performance of silver paste. The influence of the ratio of spherical silver powder to flake silver powder in silver paste on the sheet resistance, adhesion, and specific contact resistivity of silver film after sintering at 800 °C was studied, and the optimal ratio was determined according to a cross−sectional contact picture of the silver film. The results showed that with the increase in the mass fraction of the flake silver powder, the sheet resistance of the sintered silver film gradually increased, the adhesion first increased and then decreased, and the specific contact resistance first decreased and then increased. When the flake silver powder content was 0%, the minimum sheet resistance of the silver film was 2.41 m Ω/☐. When the flake silver powder content was 30%, the maximum adhesion of the silver film was 6.07 N. When the flake silver powder content was 50%, the minimum specific contact resistivity of the silver film was 0.25 Ω·cm2. In conclusion, when the flake silver powder content was 30%, the comprehensive performance of the silver film was the best.