Characterization of screen printed and fire-through contacts on LPCVD based passivating contacts in monoPoly™ 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 monoPoly™ solar cells. Extremely low recombination current density under metal contacts (J01,metal) of 35–45 fA/cm2 and excellent specific 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 demonstrate that, although the metal induced recombination increases with reducing thickness of the poly-Si layer, thinner poly-Si layers can lead to higher efficiencies on account of reduced parasitic absorption leading to higher cell current. A champion efficiency of 22.6% is reported for busbarless monoPoly™ cells with the best performing fire-through (FT) paste on large area (244.3 cm2) commercially available Czochralski grown Si wafers.