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Keywords:

  • solar cells;
  • silicon;
  • photovoltaics;
  • surface passivation

Abstract

We demonstrate industrially feasible large-area solar cells with passivated homogeneous emitter and rear achieving energy conversion efficiencies of up to 19.4% on 125 × 125 mm2 p-type 2–3 Ω cm boron-doped Czochralski silicon wafers. Front and rear metal contacts are fabricated by screen-printing of silver and aluminum paste and firing in a conventional belt furnace. We implement two different dielectric rear surface passivation stacks: (i) a thermally grown silicon dioxide/silicon nitride stack and (ii) an atomic-layer-deposited aluminum oxide/silicon nitride stack. The dielectrics at the rear result in a decreased surface recombination velocity of Srear = 70 cm/s and 80 cm/s, and an increased internal IR reflectance of up to 91% corresponding to an improved Jsc of up to 38.9 mA/cm2 and Voc of up to 664 mV. We observe an increase in cell efficiency of 0.8% absolute for the cells compared to 18.6% efficient reference solar cells featuring a full-area aluminum back surface field. To our knowledge, the energy conversion efficiency of 19.4% is the best value reported so far for large area screen-printed solar cells. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)