For solar cell metallization applications, thick film paste is a suspension of a functional (conductive) phase, binder, vehicle, and additives. Silver is the most common conductive filler used for front contact paste. The binder is composed of a glass
frit that is used to bind the functional phase to the silicon wafer. Specialized chemistry of the binder is also required to etch through anti-reflective and passivation layers and initiate effective ohmic contact between the silver and silicon. The vehicle is an organic composition that provides printability of the pastes and is composed of resins, solvents, and modifiers. The resins support the solids of the other phases and keep them in homogeneous suspension. Solvents are used to dissolve the resins, and they must be stable in production conditions. These organic components of the paste must burn off cleanly in the fast-firing process so as not to contaminate the surface of the wafers or introduce sources of recombination near the p-n junction.