A new environmental friendly silver front contact paste for crystalline silicon solar cells

This paper reports a new environmental friendly silver front contact paste for crystalline silicon solar cells. Quasi-spherical and high-dispersive silver particles were prepared from silver nitrate in hot ethylene glycol. Polyvinylpirrolidone (PVP) as a protective agent was added into the reduction system. Moreover, Bi-based glass frit powders with glass transition temperature (Tg) of 385 °C were prepared by traditional melting route. The silver front contact paste for crystalline silicon solar cells was prepared using the as-prepared superfine silver particles and Bi-based glass frit powders. The microstructures of the conductive silver thick films were investigated, which indicated that the wetting behavior and etching effect of the glass frit on silicon nitride and silicon were efficient. Besides, silver particles were sintered well with the help of the glass frit during firing processing. The fabricated solar cell containing the Bi-based glass frit as an inorganic binder showed higher Fill Factor (FF) and electrical conversion efficiency (Eff) when compared with those of the solar cell fabricated with commercial Pb-based glass frit. In short, synthesis of silver particles in hot liquid polyols is a useful method for preparing superfine and high-dispersive particles. Moreover, the Bi-based glass frit could be a suitable substitute for Pb-based glass frit for preparing environmental friendly front-side silver paste for crystalline silicon solar cells.