Aluminium-Doped p+ Silicon for Rear Emitters and Back Surface Fields: Results and Potentials of Industrial n- and p-Type Solar Cells

Abstract

We compare identically processed n- and p-type silicon solar cells with each other featuring aluminium-doped p + regions on the rear made from screen-printed paste and acting as emitter or back surface field, respectively. We investigate near-industrial large-area n + np + rear junction and n + pp + front junction cells and discuss three cell concepts with different rear side structures: (i) For solar cells with a full-area non-passivated Al-p + rear, we demonstrate similar performances on n- and p-type float-zone Si material with efficiencies of 18.6 % and 18.4 %, respectively. For our best n-type cell with a rear Al emitter coverage of 100 %, we have achieved a record-high efficiency of 19.3 %. (ii) For solar cells with a full-area and surface-passivated Al-p + rear, we have obtained an increase in the open-circuit voltage of 10 mV and in the short-circuit current density of 1.5 mA/cm 2 . (iii) For solar cells with laser-fired Al-p + points in the passivated rear Si surface, we have reached an efficiency of 19.6 % for a p-