CHARACTERIZATION OF FIRE-THROUGH PASTES ON LPCVD BASED PASSIVATING CONTACTS IN monoPolyTM SOLAR CELLS

Abstract

In this work, we have characterized screen-printed passivating contacts formed by different commercially available fire-through pastes on phosphorus-doped (n+) polysilicon (poly-Si) layers at the rear side of monoPolyTM solar cells. Extremely low recombination current density under metal contacts (J01,metal) of 35-45 fA/cm2 and excellent contact resistivity (ρc) values of ~1.3 mΩ-cm2 are obtained for two different thicknesses of poly-Si (150 nm and 250 nm) used in this work. We observe although the metal-induced recombination increases with reducing the thickness of the poly-Si layer, thinner poly-Si layers can lead to higher efficiencies on account of reduced parasitic absorption leading to higher short-circuit current. A champion efficiency of 22.6% having 5 busbars is reported for monoPolyTM cells with the best performing FT paste on large area (244.3 cm2) commercially available Czochralski grown Si wafers.